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FROM  THE  MEDICAL  LIBRARY 

OF 

DR.  CORYDON  L.  FORD. 


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3    the  University,  June.  1894.  t 

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Digitized  by  the  Internet  Arciiive 

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Open  Knowledge  Commons 


http://www.archive.org/details/systemofhumanana1843wils 


WILSON'S    ANATOMY. 


A  SYSTEM 


HUMAN    ANATOMY, 


GENERAL    AND    SPECIAL. 


BY  ERASMUS  WILSON,  M.D., 

LECTURER  OS  ANATOMY,  LONDON. 


AMERICAN    EDITION 

EDITED  BY 

PAUL   B.    GODDARD,    A.M.,    M.  D., 

DEMONSTRATOR,  OF  ANATOMY  IN  THE  UNIVERSITY  OF  PENNSYLVANIA  ;    MEMBER  OF  THE 

AMERICAN  PHILOSOPHICAL  SOCIETY;    ACADEMY  OF  NATURAL  SCIENCES  ; 

PHILADELPHIA  MEDICAL  SOCIETY,  ETC.,  ETC. 


'"'-BERr  Sr 


WITH  ONE  HUNDRED  AND  SEVENTY  ILLUSTRATIONS  BY  GILBERT, 
.      FROM    T  H  R    S  t:  (J  O  N  D    LONDON    EDITION. 


PHILADELPHIA: 

LEA     AND     B  L  A  N  C  H  A  R  D. 
1843. 


6iM 


/83 

/rh 


Mi^f 


Entered,  according  to  the  Act  of  Congress,  in  the  year  1842,  by  Lea  and 
Bi-ANCHARD,  in  the  Office  of  the  Clerk  of  the  District  Court  of  the  United 
States  in  and  for  the  Eastern  District  of  Pennsylvania. 


C.  Sherman,  Printer, 

1!)  St.  James  Street. 


^  SIR  ASTLEY  PASTON  COOPER,  Bart.,  F.R.S., 

MEMBER  OF  THE  INSTITUTE  OF  FRANCE, 

THIS  WORK 

IS  RESPECTFULLY  INSCRIBED, 

IN  ADMIRATION  OP  HIS  GREAT  AND  ACKNOWLEDGED  GENIUS; 

AND  OF  HIS  SPLENDID  AND  UNWEARYING  LABOURS 

IN  THE  CAUSE  OF  MEDICAL  SCIENCE, 

BY 

THE  AUTHOR. 


PREFACE 

TO  THE  FIRST  ENGLISH  EDITION. 


The  favourable  reception  which  my  recent  Work  on  Practical 
and  Surgical  Anatomy  has  received,  both  from  the  Profession 
and  the  press,  commands  my  first  attention  and  grateful  remem- 
brance on  again  presenting  myself  to  public  notice  as  an  aspirant 
for  honours  in  the  field  of  Medical  Science.  On  the  present 
occasion,  I  submit  the  Anatomist's  Vade  Mecum  to  the  Members 
of  the  Profession,  with  the  fullest  assurance  that  they  will  find  it 
to  be  a  complete  system  of  descriptive  Anatomy,  recording  in  its 
pages,  in  a  clear,  precise,  and  perspicuous  style  of  expression, 
every  important  detail  of  human  structure,  and  the  most  modern 
and  valuable  discoveries  and  researches  in  the  Science  of 
Anatomy. 

To  the  established  practitioner  it  is  a  matter  of  great  impor- 
tance that  he  should  be  possessed  of  the  means,  during  the  few 
spare  hours  which  he  can  abstract  from  his  anxious  and  respon- 
sible duties,  of  easily  and  agreeably  refreshing  his  acquaintance 
with  that  science  which  is  the  acknowledged  basis  of  all  safe 
and  skilful  medical  practice.  Of  this  application  of  my  pi'esent 
labours  I  have  not  been  unmindful,  in  composing  the  Anatomist's 
Vade  Mecum ;  and  I  sincerely  trust  that  the  work  will  prove  to 
be  the  instructive  and  interesting  companion  of  his  important 
practical  avocations. 

The  Student  of  Medicine,  from  the  first  moment  of  commen- 
cing his  labours  in  the  study  of  Anatomy,  must  be  made  aware 
of  the  absolute  necessity  that  exists  for  clearness  of  thought,  ex- 
actness of  language,  and  a  rigorous  arrangement  of  ideas.  He 
must  feel  confidence  in  the  knowledge  which  he  possesses,  and 
he  will  then  exhibit  that  confidence  in  the  decision  by  which  all 

2 


his  actions  will  be  characterized.  As  a  text-book  for  illustrating 
in, a  precise  method  the  materials  of  instruction,  this  work  is 
especially  designed ;  and  the  severity  and  inflexibility  of  order 
have  not  been  departed  from  in  treating  of  a  single  branch  of  the 
subject. 

Among  the  modern  investigations  of  great  interest  of  which  I 
have  availed  myself,  I  may  particularly  enumerate  those  of  Sir 
Astley  Cooper,  Kiernan,  Henle,  Good  sir,  and  Searle,  in  addition 
to  the  important  observations  of  other  excellent  anatomists. 

My  thanks  are  especially  due  to  Sir  Astley  Cooper,  who,  with 
his  usual  urbanity,  has  furnished  me  with  much  useful  informa- 
tion, and  has  permitted  me  to  emblazon  my  pages  with  the  flat- 
tering patronage  of  his  name.  I  have  regarded  this  condescen- 
sion of  so  distinguished  a  surgeon  and  physiologist  as  a  sacred 
trust  reposed  in  my  hands,  and  I  have  exerted  myself  to  render 
my  labours  not  unworthy  of  such  gratifying  confidence. 

I  hope  I  may  be  permitted  to  say  that  the  Engravings  are 
beautiful  examples  of  a  most  instructive  and  valuable  art.  The 
advantages  of  such  illustrations  in  a  demonstrative  science  cannot 
be  too  highly  appreciated.  The  mode  in  which  the  Engravings 
have  been  printed, — a  distinct  branch  of  art  in  itself, — will  not 
pass  unnoticed  by  those  who  are  acquainted  with  the  complicated 
process  and  extreme  care  which  are  necessary  to  the  production 
of  the  dehcacy  and  force  of  effect  of  such  graphic  illustrations. 

In  conclusion,  it  giv^es  me  much  pleasure  to  express  the  obliga- 
tions which  are  due  from  me  to  my  friend  and  late  pupil  Mr. 
Oliver  Thomas  Miller,  of  Her  Majesty's  Navy,  for  the  patient 
and  industrious  perseverance  with  which  he  devoted  his  time  and 
ability  during  the  summer  months  to  assist  me  in  the  prosecution 
of  my  labours. 

55  Upper  Charlotte  Street,  Fitzroy  Square, 
March  1840. 


PREFACE 


TO  THE  SECOND  ENGLISH  EDITION. 


Two  years  have  not  yet  elapsed  since  the  First  Edition  of  the 
Anatomist's  Vade  Mecum  was  presented  to  the  Public ;  but  that 
short  period,  brief  though  it  is,  has  been  most  eventful  as  regards 
the  history  of  this  work. 

The  most  prominent  of  the  events  to  which  I  allude  is  the 
departure  from  this  earthly  sphere  of  the  distinguished  patron  of 
my  undertaking.  When  he  was  pleased  to  crown  my  labours 
with  his  sanction,  and  lend  to  them  the  brightness  of  his  name,  he 
was  in  the  enjoyment  of  perfect  health ;  he  was  still  labouring  in 
the  field  of  Medical  Science,  an  untiring  labourer ;  he  was  still 
looking  forward  to  a  long  vista  of  usefulness  and  benevolent 
action.  Now,  Sir  Astley  Cooper  is  no  more.  It  is  not  my  in- 
tention,— and,  indeed,  if  I  were  so  inclined,  I  should  lack  the 
ability, — to  write  the  eulogium  of  that  universally  esteemed  and 
noble-hearted  man.  I  shall  content  myself  with  remarking,  that 
in  him  I  have  lost  a  kind  and  a  warm  friend,  the  Medical  Pro- 
fession a  distinguished  ornament,  and  society  a  consolation  and  a 
resource  under  the  torments  of  disease.  Sir  Astley  Cooper  was 
doubly  eminent ;  he  was  great  as  a  scientific  surgeon,  but  he  was 
greater  as  a  man :  and  though  in  his  former  capacity  his  name 
will  be  remembered  as  long  as  letters  endure,  his  memory  will 
survive  until  the  human  heart  shall  cease  to  vibrate  to  the  note  of 
sympathy  and  benevolence. 

But  while  I  am  thus  humbly  endeavouring  to  do  justice  to  my 
own  feelings  in  recording  a  feeble  tribute  towards  a  great  debt  of 
gratitude  which  I  owe  to  the  memory  of  Sir  Astley  Cooper,  I  do 
not  forget  that  my  warmest  thanks  are  also  due  to  my  other 
patrons,  the  Medical  Practitioners  and  Students  of  Great  Britain, 
and  to  the  conductors  of  the  Medical  Press.     From  the  former  1 


take  this  opportunity  of  acknowledging  the  receipt  of  numerous 
letters  containing  the  most  cheering  and  gratifying  expressions ; 
and  to  the  latter  I  am  indebted  for  the  independence  of  opinion, 
and  liberality  of  sentiment,  with  which  they  have  regarded  my 
labours. 

It  has  been  no  slight  source  of  gratification  to  me,  that  the 
work  should  have  received  so  much  attention  from  the  profession 
in  distant  countries.  The  Anatomist's  Vade  Mecum  is  to  be 
reprinted  in  the  United  States  of  America ;  it  is  at  this  moment 
undergoing  translation  at  Berlin ;  while  repeated  overtures  have 
been  made  to  Mr.  Churchill  for  its  publication  in  France. 

I  have  endeavoured  to  render  the  present  Edition  more  perfect 
than  the  preceding,  by  entering  more  fully  into  the  description  of 
such  parts  as  were  only  scantily  treated  in  the  first.  I  regret 
that  these  additions  have  increased  the  size  of  the  volume, — an 
effect  that  it  has  always  been  my  foremost  desire  to  avoid ;  for  if 
a  large  and  a  verbose  book  be  at  any  time  a  great  evil,  it  is  so 
to  its  fullest  extent  in  a  volume  which  is  intended  to  record  only 
facts,  as  is  the  case  with  a  work  on  Anatomy. 

In  the  present  Edition,  as  in  the  former,  I  have  availed  myself 
of  the  labours  of  those  who  have  been  pursuing  successfully 
separate  branches  of  our  science.  Of  them,  I  have  recorded  the 
investigations  of  Mr.  Bowman,  of  King's  College,  on  the  minute 
anatomy  of  muscular  fibre ;  of  Mr.  Nasmyth,  on  the  developement 
of  the  epithelium ;  and  of  Mr.  Curling,  of  the  London  Hospital, 
on  the  descent  of  the  testis  in  the  foetus.  I  have  also  contributed 
in  this  department  some  original  researches,  which  I  have  myself 
made,  on  the  minute  structure  of  bone. 

The  principal  additions  to  the  present  Edition  will  be  found  in 
the  chapters  on  the  ligaments,  muscles,  nervous  system,  organs 
of  sense,  and  viscera.  I  have  appended  to  each  muscle  a 
separate  paragraph,  indicating  its  relations  to  surrounding  parts ; 
and  have  augmented  the  number  of  wood-cut  illustrations. 

January  1812. 


PREFACE 

TO  THE  AMERICAN  EDITION. 


In  republishing  the  present  work,  it  was  thought  that  its  origi- 
nal title  "  Wilson's  Anatomist's  Vade  Mecum,"  would  lead  to 
an  incorrect  appreciation  of  the  nature  and  extent  of  the  work ; 
the  term  "  Vade  Mecum"  being  in  this  country  usually  applied 
to  small  and  concise  manuals.  The  present  work  is,  as  its 
American  title  implies,  a  complete  System  of  Human  Anatomy, 
brought  up  to  the  present  day,  and  although  it  is  written  in  a 
curt  and  concise  style,  nothing  is  omitted  which  can  be  deemed 
important  by  the  student  or  the  general  practitioner. 

In  some  points  its  author  had  not  described  parts  and  structures 
with  sufficient  accuracy,  and  had  evidently  neglected  the  contri- 
butions to  the  science  from  this  side  of  the  water ;  these  defi- 
ciencies I  have  endeavoured  to  supply  by  notes  and  additional 
illustrations.  Some  few  alterations  of  names  have  been  made  in 
the  body  of  the  work,  where  the  author's  names  were  too  English 
and  not  in  common  use  in  the  United  States. 

The  illustrations  are  by  far  the  most  beautiful  which  have  ever 
appeared  in  any  anatomical  work,  and  much  praise  is  due  Mr. 
R.  S.  Gilbert  of  this  city  for  the  masterly  and  spirited  manner  in 
which  he  has  copied  them.  The  originals  were  designed  and 
executed  expressly  for  this  work,  by  Bagg,  of  London,  whose 
reputation  in  this  branch  of  art  is  deservedly  high. 

I  have  long  been  convinced  that  the  day  would  come  in  which 
it  would  be  useless  to  present  to  the  public  a  work  on  science. 


XIV  PREFACE. 

unless  it  was  accompanied  with  numerous  and  exact  illustrations, 
as  the  road  to  the  mind  is  so  much  shorter  and  easier  through 
the  eye,  than  any  other  avenue.  This  fact  has  been  appreciated 
by  the  student  of  anatomy  for  some  time,  and  although  numerous 
splendid  works  have  appeared,  there  has  been  none  which  gave 
so  many  and  exact  views  at  so  low  a  cost,  as  the  present. 

Paul  B.  Goddard. 

Philadelphia,  October  1842. 


CONTENTS. 


CHAPTER   I. 


OSTEOLOGY. 

Definition — Chemical     composi- 

Regions of  the  skull . 

55 

tion  of  bone — Division  in- 

Base of  the  skull    . 

. 

59 

to  classes         -         .         - 

17 

Face      - 

, 

60 

Structure  of  bone       .         -         . 

18 

Orbits 

. 

61 

Developement  of  bone 

21 

Nasal  fossae 

. 

62 

The  skeleton      -         .         .         - 

22 

Teeth 

. 

63 

Vertebral  column 

23 

■  Structure 

, 

64 

Cervical  vertebrae  ... 

24 

Developement 

. 

65 

Atlas — Axis  .         -         .         -i 

24-25 

Growth 

. 

68 

Vertebra  prominens 

26 

Eruption 

. 

68 

Dorsal  vertebrae 

26 

Succession     - 

. 

69 

Lumbar  vertebrce   ... 

27 

Os  hyoides 

, 

70 

General  considerations   - 

27 

Thorax  and  upper  extremity 

70 

Developement         -         .         . 

28 

Sternum — Ribs 

- 

71 

Attachment  of  muscles  - 

28 

Costal  cartilages     - 

. 

72 

Sacrum 

29 

Clavicle — Scapula  - 

. 

73 

Coccyx  

30 

Humerus 

. 

75 

Bones  of  the  cranium 

30 

Ulna      . 

. 

76 

Occipital  bone         -         .         . 

30 

Radius  ... 

. 

77 

Parietal  bone           ... 

33 

Carpal  bones 

. 

79 

Frontal  bone 

34 

Metacarpal  bones  . 

. 

82 

Temporal  bone       ... 

36 

Phalanges 

. 

84 

Sphenoid  bone         ... 

40 

Pelvis  and  lower  extremity 

84 

Ethmoid  bone         ... 

44 

Os  innominatum     - 

. 

85 

Bones  of  tlie  face       ... 

45 

Ilium — Ischium     - 

_ 

85 

Nasal 

45 

Os  pubis 

. 

85 

Superior  maxillary 

45 

Pelvis  —  Its  Divisions 

—  Axes 

Lachrymal  bone     - 

48 

— Diameters  - 

. 

88 

Malar  bone — Palate  bone 

48 

Femur  - 

. 

89 

Inferior  turbinated  bone 

51 

Patella— Tibia 

. 

91 

Inferior  maxillary  -         -         - 

51 

Fibula  - 

. 

93 

Table  of  developements,  articula- 

Tarsal bones  - 

. 

94 

tions,  &c. 

53 

Metatarsal  bones    . 

_ 

95 

Sutures               -        -        .        . 

54 

Phalanges 
Sesamoid  bones 

- 

98 
99 

CHAPTER   II. 

THE  LIGAMENTS. 


Forms  of  articulation  -         -  100 

Synarthrosis  —  Amphi-arthro- 

sis — Diartbrosis       -         -  101 

Movements  of  joints  -         -         .  102 


Gliding — Angular  movement  -  103 

Circumduction — Rotation        -  102 
General    anatomy    of    articular 

structures        -         .         -  102 


XVI 

Cartilage — Fibro-cartilage 
Ligament  —  Synovial     mem- 
brane     -         -        .         - 
Ligaments  of  the  trunk — Ar- 
rangement     ... 
Articulation  of  the  vertebral  co- 
lumn      .         -        .        - 
Of  the  atlas  with  the  occipital 
bone       .         .         .         - 
Of  the  axis  with  the  occipital 
bone        .         .         -         - 
Of  the  atlas  with  the  axis 
Of  the  lower  jaw  -         .         . 
Of  the  ribs  witli  tlie  vertebrte 
Of  the  ribs  witli  the  sternum, 

and  with  each  other 

Of  the  vertebral  column,  with 

the  pelvis         ... 

Of  tlie  pelvis-         ... 

Ligaments  of  the  upper  extre- 

MITY         .  -  -  - 

Sterno-clavicular  articulation 

Scapulo-clavicular  articulation    - 


CONTENTS. 

102 

Ligaments  of  the  scapula  - 

120 

Shoulder-joint    .... 

120 

103 

Elbow-joint        .... 

121 

Radio  ulnar  articulation     - 

123 

104 

Wrist-joint         .... 

124 

Articulations  of  the  carpal  bones 

125 

104 

Carpo-metacarpal  articulation     - 
Metacarpo-phalangeal     articula- 

126 

107 

tion         .... 

127 

Articulation  of  the  phalanges     . 

127 

108 

Ligaments  of  the  lower  extre- 

108 

mity        .... 

128 

110 

Hip-joint 

128 

112 

Knee-joint          .... 
Articulation   between   the    tibia 

12:j 

113 

and  fibula        ... 

134 

Ankle-joint         .... 

135 

114 

Articulation  of  the  tarsal  bones  - 

13(; 

115 

Tarso-mctatarsal  articulation 
Metatarso-phalangeal      articula- 

138 

117 

tion         .... 

139 

118 

Articulation  of  the  phalanges     - 

139 

119 

CHAPTER   III. 


General  anatomy  of  muscle 
Nomenclature — Structure 
Muscles  of  the  head  and  face  . 
Arrangement  into  groups  - 
Epicranial  region — Dissection 

Occipito-frontalis    - 
Orbital  group — Dissection 
Orbicularis  palpebrarum 
Corrugator  supcrcilii — Tensor 

tarsi 
Actions  ... 

Ocular  group — Dissection  . 
Levator  palpcbra3 — Rectus  su. 

perior 
Rectus  inferior — Rectus  intcr- 

nus 
Rectus  cxternus — Obliquus  su- 
perior     .         .         - 
Obliquus  inferior — Actions 
Nasal  group 

Pyramidalis  nasi    . 
Compressor  nasi — Actions 
Superior  labial  group 

Orbicularis  oris — Levator  labii 

supcrioris  aheque  nasi 
Levator    labii    supcrioris    pro- 

prius 
Levator  anguli  oris — Zygoma- 
tic! 
Depressor  labii  supcrioris  ala)- 

quc  nasi  - 
Actions .... 
Inferior  labial  group  . 
Dissection 


THE    MUSCLES. 

-     140 

Inferior  labial  group — continued. 

-     141 

Depressor  labii  inferioris 

153 

.    144 
.     144 

Depressor  anguli  oris — Leva- 
tor  labii  inferioris    - 

153 

-     145 

Actions           .... 

153 

.     145 

-  146 

-  146 

Maxillary  group 

Masseter — Temporal  muscle  - 
Buccinator — External     ptery. 

153 
154 

goid  muscle     - 

155 

-  147 

-  147 

Internal  pterygoid  muscle 
Actions 

156 
156 

.     147 

Auricular  group          ... 

156 

Dissection      .... 

156 

-     148 

Attollcns    aurem — Attrahens 

aurem     .... 

156 

-     149 

Retrahens  aurem — Actions     - 

J  57 

Muscles  of  the  neck 

157 

.     149 

Arrangement  into  groups  . 

157 

-     150 

Superficial  group — Dissection     - 

158 

-     150 

Phitysma  myoides - 

158 

-     150 

Stcrno-cleido-mastoideus — Ac 

-     151 

tions        .... 

158 

-     151 

Depressors  of  the  os  hyoides  and 

.     151 

larynx    .         -         -         . 

Dissection      .         .         -         - 
Stcrno-liyoideus  —  Stcrno-thy- 

160 
100 

-     152 

roideus   .         .         -         - 

100 

-     152 

Thyro-Iiyoideus  —  Omo-hyoi- 
deus        .... 

161 

Actions           .... 

101 

.     152 

Elevators  of  the  os  hyoides 

161 

.    152 

Dissection      .... 

162 

.     153 

Diirasti'icus    -         -         .         . 

J  (\2 

-     153 

Stylo- hyoideus — inylo-hyoidcus 

162 

CONTENTS. 


XVll 


Genio-hyoideus  —  Genio-hyo- 

glossus  -         -         -         -  163 
Actions          -        -        -        -  163 
Muscles  of  the  tongue        -         -  163 
Hyo-glossus — Lingualis          -  1 64 
Stylo-glossus           -         -         -165 
Palato-g-lossus — Actions          -  165 
Muscles  of  the  pharynx      -         -  1 65 
Dissection      -         -         -         -  165 
Constrictor  inferior          -         -  166 
Constrictor  medius — Constric- 
tor superior     -         -        -  16G 
Stylo  -  pharyngeus  —  Palato- 

pharyngeus — Actions       -  167 

Muscles  of  the  soft  palate  -        -  168 

Dissection      -        -         -         -  168 

Levator  palati — Tensor  palati  168 

Azygos  uvulfE — Palato-glossus  169 

Palato-pharyngeus — Actions  169 

Prsevertebral  muscles          -         -  170 

Dissection      -         -         -         -  170 
Rectus  anticus  major — Rectus 

anticus  minor           -         -  170 
Scalenus    anticus  —  Scalenus 

posticus           -        -         -  170 
Longus  colli  -         -        -         -  171 
Actions          ....  171 
Muscles  of  the  trunk      -        -  172 
Muscles  of  the  back — Arrange- 
ment      ....  172 
First  layer — Dissection  -         -  173 
Trapezius  -         -         -         -  173 
Latissimus  dorsi         -         -  174 
Second  layer — Dissection        -  174 
Levator  anguli  scapulae        -  174 
Rhomboideus      minor       et 

major  -         .         -         .  176 

Third  layer — Dissection          .  176 
Serratus  posticus  superior  et 

inferior  -         -        -        -  176 

Splcnius  capitis  et  colli        -  177 

Fourth  layer — Dissection        -  177 
Sacro-lumbalis  —  Longissi- 

mus  dorsi        -         -         -  177 

Spinalis  dorsi      -         .        .  177 
Cervicalis  ascendens — Trans- 

versalis  colli    -         -         -  178 

Trachelo-mastoideus — Com- 

plexus    -         -        -         -  179 

Fifth  layer — Dissection  -         -  179 

Semispinalis  dorsi  et  colli    -  180 

Rectus  posticus,    major    et 

minor     ....  ISO 
Rectus    lateralis — Obliquus 

inferior  -         -         -         -  180 

Obliquus  superior        -         -  130 

Sixth  layer — Dissection  -         -  180 
Multifidus  spinae — Levatores 

costarum        -         -         -  181 
Supra-gpinales  —  Inter-spi- 

nales       ....  181 

Intcr-transversales       -        -  181 

Actions       ....  182 
Table  of  origins  and  insertions  of 

the  muscles  of  the  back   -  184 


Muscles  of  the  thorax 

186 

Intercostales  externi  et  interni 

186 

Triangularis  sterni 

188 

Actions           .         .         ,         . 

188 

Muscles  of  the  Abdomen    . 

188 

Dissection      .         .         .         . 

188 

Obliquus  externus 

188 

Obliquus  internus — Cremaster 

189 

Transversalis — Rectus    . 

191 

Pyramidalis — Quadratus  lum- 

borum — Psoas  parvus 

193 

Diaphragm     .         .         .         . 

194 

Actions           .         .         .         . 

195 

Muscles  of  the  perineum    - 

196 

Dissection      .         .         .         . 

196 

Acceleratores  urinaj 

197 

Erector   penis  —  Transversus 

perinei    .         .         .         . 

197 

Compressor  urethrcB 

198 

Sphincter  and  externus  et  in. 

ternus     .         .         .         . 

199 

Levator  ani — Coccygeus 

199 

Muscles   of  the   female   peri- 

neum     .... 

200 

Muscles    of     the    upper     ex- 

tremity         ... 

201 

Anterior  thoracic  region     . 

202 

Dissection      .... 

202 

Pectoralis  major    - 

203 

Pectoralis   minor — Subelavius 

— Actions 

203 

Lateral  thoracic  region 

204 

Serratus  magnus — Actions 

204 

Anterior  scapular  region    . 

204 

Scapularis      .... 

204 

Actions           .... 

205 

Posterior  scapular  region   - 

205 

Supra-spinatus  —  Infra-spina- 

tus          ... 

205 

Teres  minor — Teres  major 

205 

Actions          .... 

206 

Acromial  region         -         -         . 

206 

Deltoid — Actions   ... 

206 

Anterior  humeral  region    - 

207 

Dissection      -         .         -         . 

207 

Coraco-brachialis — Biceps 

207 

Brachialis  anticus — Actions    - 

209 

Posterior  humeral  region    . 

209 

Triceps           .... 

209 

Anterior  brachial  region     . 

210 

Superficial  layer — Dissection  • 

210 

Pronator  radii  teres     . 

210 

Flexor  carpi  radialis   - 

210 

Palmaris  longus 

210 

Flexor  sublimis  digitorum  . 

211 

Flexor  carpi  ulnaris    - 

212 

Deep  layer — Dissection 

212 

Flexor  profundus  digitorum 

212 

Flexor  longus  pollicis 

213 

Pronator    quadratus  —  Ac- 

tions       .... 

213 

Posterior  brachial  region 

213 

Superficial  layer  —  Dissec 

tion        .... 

213 

Supinator  longus 
3 

214 

XVIU 


CUNTEKTS, 


Posterior  brachial  region — continue 
Extensor  carpi  radialis  lon- 

gior        -         -         - 
Extensor  carpi  radialis  bre- 
vier        .         .         .         - 
Extensor  communis  digito- 
rum         ...         - 
Extensor  minimi  digiti 
Extensor  carpi  ulnaris — An- 
coneus   -         -         -         - 
Deep  layer — Dissection  - 
Supinator  brevis 
Extensor    ossis     metacarpi 
pollicis    -         -         -         - 
Extensor    primi    internodii 
pollicis    -         -         -         . 
Extensor  secundi  internodii 
pollicis    -         -         -         - 
Extensor  indicis 
Actions       .         -         -         - 
Muscles  of  the  hand   - 

Radial  region — Dissection 
Ulnar  region — Dissection 
Palmar  region         -         -         - 
Actions  .         -         -         - 

Muscles  of  the  lower  extre- 
mity      .        -        -        - 
Gluteal  region — dissection 

Gluteus  maximus  -  -  - 
Gluteus  medius  et  minimus  • 
Pyriformis  .  .  -  - 
Gemellus  superior — Obturator 
internus  -  .  -  - 
Gemellus  inferior — Obturator 
externus  ... 

Quadratus  femoris 
Actions  .... 

Anterior  femoral  region — Dissec- 
tion        .... 
Tensor  vaginse  femoris — Sar- 
torius      -         -         .         - 
Rectus — Vastus  externus 
Vastus  internus — Crureus 


ed. 

Anterior  femoral  region — continued. 

Actions          .... 

229 

214 

Internal  femoral  region — Dissec- 

tion        .... 

229 

214 

Iliacus  internus 

Psoas  magnus  —  Pectineus — 

229 

214 

Abductor  Inngus 

230 

216 

Abductor    brevis  —  Abductor 

magnus — Gracilis   - 

231 

216 

Actions           .... 

232 

216 

Posterior    femoral   region — Dis- 

216 

section    .... 

232 

Biceps  flexor  cruris 

232 

217 

Semi-tendi  n  osus  —  Semi-mem- 

branosus 

233 

217 

Actions          .         .         .         - 

234 

Anterior  tibial  region — Dissection 

234 

217 

Tibialis  anticus 

234 

217 

Extensor  longus  digitorum      - 

234 

218 

Peroneus    tertins  —  Extensor 

218 

proprius  pollicis 

235 

218 

Actions           .... 

236 

219 

Posterior  tibial  region 

236 

220 

Superficial  layer — Dissection 

221 

Gastrocnemius    . 

236 

Plantaris — Soleus — Actions 

237 

222 

Deep  layer — Dissection  - 

237 

223 

Popliteus  —  Flexor  longus 

224 

pollicis    .         -         -         . 

238 

224 

Flexor  longus  digitorum 

225 

Tibialis  posticus 

238 

Actions      .... 

240 

225 

Fibular  region  .... 
Peroneus  longus — Peroneus 

240 

22G 

brevis     .... 

240 

226 

Actions      .... 

241 

226 

Foot — Dorsal  region  - 

241 

Plantar  region 

-241 

227 

First  layer — Dissection 

241 

Second  layer — Dissection    - 

243 

227 

Third  layer — Dissection 

244 

228 

Fourth  layer 

245 

229 

Actions       .... 

245 

CHAPTER    IV. 


THE  FASCI^>, 


General  anatomy       -  -  -  246 

Fasciae  of  the  hkad  and  neck  -  247 

Temporal  fascia     -  -  -  247 

Cervical  fascia        -  -  -  247 

Fascia  of  the  trunk  -  -  249 

Thoracic  fascia      -  -  -  249 

Fascia  transversalis  -  -  249 

Oblique  inguinal  hernia  -  -  250 

Congenital  hernia       -  -  -  251 

Encysted  hernia         -  -  -  251 

Direct  inguinal  hernia  -  -  251 


Fascia  iliaca      .         -         -         .  252 

Fascia  pelvica   ....  252 

Obturator  fascia  ...  252 

Superficial  perineal  fascia  -         -  253 

Deep  perineal  fascia  ...  253 

FASCIyEOF  THE  UPPER  EXTREMITY  256 
FaSCI.15     of    the     LOWER     EXTRE. 

MITV  ....  256 

Fascia  lata         ....  257 

Femoral  hernia       ...  259 

Plantar  fascia    ....  260 


CONTENTS. 


CHAPTER   V. 


THE  ARTERIES. 


General  anatomy  of  arteries       -  262 

Inosculations — Structure    -        -  263 

Aorta 264 

Table  of  branches  -         -  268 

Coronary  arteries       -         -         -  268 

Arteria  innominata    ...  268 

Common  carotid  arteries    -         .  269 

External  carotid  artery       -         -  270 

Table  of  branches  .         -  271 

Superior  thyroid  artery  -         -  271 

Lingual  arlery        ...  273 

Facial  artery  ...  273 

Mastoid  artery        -         -         .  275 

Occipital  artery      ...  275 

Posterior  auricular  artery        .  275 

Parotidean  arteries  -         .  275 

Ascending  pharyngeal  artery  275 

Transverse  facial  artery  -  276 

Temporal  artery     -         .         .  276 

Internal  masiUary  artery         -  276 

Internal  carotid  artery        .         .  278 

Ophthalmic  artery  .         .  279 

Anterior  cerebral  artery  .  281 

Middle  cerebral  artery    -         .  281 

Subclavian  artery       ...  281 

Table  of  branches  -         .  283 

Vertebral  artery      ...  283 

Basilar  artery         .         .         .  284 

Thyroid  axis — Inferior  thyroid 

artery       ....  285 
Supra-scapular  artery — Poste- 
rior scapular    ...  285 
Circle  of  WiUis      -         .         .  286 


Subclavian  artery — continued. 
Superficialis  cervicis — Profun- 
da cervicis         ...  287 
Superior  intercostal  artery — In. 

ternal  mammary        -         .  287 

Axillary  artery ....  288 

Table  of  branches  ...  289 

Brachial  artery  ....  291 

Radial  artery     -         .         .         -  292 

Ulnar  artery      -         .         .         -  295 

Thoracic  aorta  ;  branches  -         .  297 

Abdominal  aorta;  branches        .  298 

Phrenic  arteries      .         -         -  298 

Cceliac  axis — Gastric  artery    -  298 

Hepatic  artery        .         -         -  299 

Splenic  artery         ...  300 

Superior  mesenteric  artery      .  301 

Spermatic  arteries           -         .  303 

Inferior  mesenteric  artery       .  304 

Renal  arteries         -         -         -  305 

Common  iliac  arteries         -         -  306 

Internal  iliac  artery  -        -         .  306 

Ischiatic         ....  308 

Internal  pudic  artery      -         .  309 

External  iliac  artery  .         -         .  312 

Femoral  artery  -         -         -         .313 

Pophteal  artery          .         .         .  317 

Anterior  tibial  artery          -         -  318 

Dorsalis  pedis  artery           -         -  320 

Posterior  tibial  artery         •         -  322 

Peroneal  artery      -         -         -  322 

Plantar  arteries          ...  323 

Pulmonary  artery      ...  325 


CHAPTER   VI. 


THE  VEINS. 


General  anatomy       .         .  .327 

Veins  of  the  head  and  neck  -     329 

Veins  of  the  diplofi    -         .  .330 

Cerebral  and  cerebellar  veins  -     331 

Sinuses  of  the  dura  mater  -     331 

Veins  of  the  neck      -         -  .     334 

Veins  of  the  upper  extremity  -     336 

Veins  of  the  lower  extremity  .     338 

Veins  of  the  trunk     -         -  -     339 
Venffi  innominatcB  ...     339 


Veins  of  the  trunk — continued. 

Superior  vena  cava  -         -  339 

Iliac  veins      ....  340 

Inferior  vena  cava  ...  341 

Azygos  veins  -         .         .  342 

Vertebral  and  spinal  veins       -  343 

Cardiac  veins  -         -         -  344 

Portal  vein     .         .         .        .  344 

Pulmonary  veins        ...  346 


CONTENTS. 


CHAPTER   VII. 


THE  LYMPHATICS. 


General  anatomy        -         -         -  347 

Lymphatics  of  the  head  and  neck  348 
Lymphatics  of  the  upper  extre- 

mity  -  -  -  -  349 
Lymphatics  of  the  lower  extre- 

mity         ....  350 


Lymphatics  of  the  trunk    -         -  351 

Lympliatics  of  the  viscera  -  352 

Lacteals         ....  354 

Thoracic  duct   ....  354 

Ductus  lymphaticus  dexter         -  356 


CHAPTER    VIII. 


THE  NERVOUS  SYSTEM. 


General  anatomy 

357 

Spinal  cord 

The  brain          .... 

362 

Cranial  nerves   - 

Membranes  of  the  encephalon    - 

362 

Nerves  of  special  sense 

Dmra  mater    .         .         .         - 

363 

Nerves  of  motion  - 

Arachnoid  membrane     - 

365 

Respiratory  nerves 

Pia  mater       .         .         .         - 

366 

Trifacial  nerve 

Cerebrum           .... 

366 

Spinal  nerves     - 

Lateral  ventricle     .        .         - 

367 

Cervical  plexus 

Fifth  ventricle        ... 

371 

Brachial  plexus 

Third  ventricle 

373 

Dorsal  nerves 

Fourth  ventricle     ... 

374 

Lumbar  nerves 

Lining  membrane  of  the  ven- 

Sacral nerves 

tricles       .         -         -         - 

375 

Sympathetic  system  - 

Cerebellum        .         .         .         - 

375 

Cranial  ganglia 

Base  of  the  brain 

376 

Cervical  ganglia 

Medulla  oblongata      -         -         - 

378 

Thoracic  ganglia    - 

Diverging  fibres          ... 

380 

Lumbar  ganglia 

Converging  fibres;  commissures 

382 

Sacral  ganglia 

383 
386 
386 
387 
390 
398 
403 
404 
407 
413 
415 
419 
425 
425 
430 
432 
434 
434 


CHAPTER   IX. 


ORGANS  OF  SENSE. 


Nose 

Nasal  fossae        .... 

Eyeball 

Sclerotic  coat  and  cornea 
Choroid  coat ;  ciliary  ligament; 
iris  -         -         -         -         - 
Retina  ;  zonula  ciliaris   - 
Humours        -         -         -   .      - 
Physiological  observations 

Appendages  of  the  eye 

Lachrymal  apparatus 

Organ  of  hearing       -         .         - 
External  car  ;  pinna  ;  meatus 


435 

Organ  of  hearing — continued. 

437 

Tympanum    .         -         -         - 

452 

438 

Ossicula  auditCis     - 

452 

439 

Muscles  of  the  tympanum 

454 

Internal  ear — Vestibule  - 

456 

440 

Semicircular  canals 

459 

443 

Cochlea          .... 

459 

444 

Membranous  labyrinth   - 

460 

446 

Organ  of  taste — Tongue    - 

462 

447 

Organ  of  touch — Skin 

464 

448 

Appendages  to  the  skin — Nails  - 

467 

450 

Hairs — Sebaceous  glands 

467 

450 

Perspiratory  ducts — Pores 

467 

CONTENTS. 


CHAPTER   X. 


THE    VISCERA. 

Thorax    .         .         .         - 

469 

Abdomen — continued. 

Heart        .... 

. 

469 

Anus 

- 

506 

Pericardium      ... 

. 

470 

Liver     ... 

- 

511 

Adult  circulation 

. 

471 

Kiernan's  researches 

- 

515 

Structure  of  the  heart — Searle's 

Gall-bladder  . 

- 

522 

researches 

. 

476 

Pancreas 

- 

523 

Organs  of  respiration  and  voice  - 

4S0 

Spleen    - 

- 

524 

Larynx — Cartilages 

. 

480 

Supra-renal  capsules 

- 

525 

Ligaments — Muscles  - 

. 

481 

Kidneys 

- 

526 

Trachea  and  Bronchi      - 

. 

485 

Pelvis 

- 

529 

Thyroid  gland 

. 

486 

Bladder 

. 

529 

Lungs    .         .         .         - 

. 

486 

Prostate  gland 

. 

532 

Pleurae  .         -         .         - 

. 

489 

Vesiculse  seminales 

. 

533 

Mediastinum  - 

. 

489 

Male  organs  of  generation 

534 

Abdomen — Regions    . 

. 

490 

Penis     ... 

. 

534 

Peritoneum    -         -         . 

. 

491 

Urethra 

. 

536 

Alimentary  canal  - 

. 

495 

Testes   . 

- 

539 

Lips— Cheeks — Gums- 

-Pa. 

Female  pelvis  - 

. 

543 

late 

. 

496 

Bladder — Urethra  - 

. 

543 

Tonsils — Fauces    - 

. 

497 

Vagina  - 

. 

544 

Salivary  glands 

. 

497 

Uterus  - 

. 

544 

Pharynx        ... 

. 

499 

Fallopian  tubes 

- 

547 

Stomach         ... 

. 

500 

Ovaries  - 

. 

547 

Small  intestine 

. 

502 

External  organs  of  generation 

548 

Large  intestine 

. 

503 

Mammary  glands 

. 

550 

Structure  of  the  intestinal  canal 

504 

CHAPTER  XL 


Osseous  and  ligamentous  system 
Muscular  system 
Vascular  system 
Foetal  circulation 
Nervous  system 
Organs   of  sense — Eye- 
Nose 
Thyroid  gland  - 
Thymus  gland  - 


ANATOMY    OF 

THE    FCETUS. 

3  system 

552 

Foetal  lungs       .... 

558 

. 

552 

Foetal  heart        .... 

558 

. 

552 

Viscera  of  the  abdomen 

559 

- 

552 

Omphalo-mesenteric  vessels    - 

559 

. 

555 

Liver 

560 

— Ear— 

Kidneys  and  supra-renal  cap- 

. 

555 

sules       .... 

560 

. 

555 

Viscera  of  the  pelvis  .         .        - 

560 

. 

556 

Testes — Descent    - 

561 

TABLE  OF  ILLUSTRATIONS. 


1. 

Minute  Structure  of  bone  - 

20 

35. 

Femur ;  posterior  view 

91 

2. 

Cervical  vertebra 

24 

36. 

Tibia  and  fibula 

92 

3. 

Atlas          .... 

25 

37. 

Foot ;  dorsal  surface  - 

94 

4. 

Axis 

25 

38. 

Foot ;  plantar  surface 

97 

5. 

Dorsal  vertebra  - 

26 

39. 

Ligaments  of  the  vertebrae 

6. 

Lumbar  vertebra 

27 

and  ribs ;  anterior  view  - 

105 

7. 

Sacrum      .... 

29 

40. 

Posterior  common  ligament 

106 

8. 

Occipital   bone  —  External 

41. 

Ligamenta  subflava    . 

106 

surface    .... 

30 

42. 

Ligaments  of  the  atlas,  axis, 

9. 

Occipital    bone  —  Internal 

and  occipital  bone,  ante- 

surface   .... 

32 

rior  view 

107 

10. 

Parietal    bone  —  External 

43. 

Id. ;  posterior  view     - 

107 

surface    .... 

33 

44. 

Id. ;  internal  view 

108 

11. 

Parietal    bone  —  Internal 

45. 

Id. ;  internal  view 

109 

surface    -         .         .         - 

33 

46. 

Ligaments  of  the  lower  jaw ; 

12. 

Frontal     bone  —  External 

external  view  ... 

110 

surface    .... 

35 

47. 

Id  ;  internal  view 

111 

13. 

Frontal  bone — Internal  sur- 

48. 

Id. ;  section 

111 

face         .... 

36 

49. 

Ligaments  of  the  vertebral 

14. 

Temporal  bone  —  External 

column  and  ribs ;   poste. 

surface    .... 

36 

rior  view 

113 

15. 

Temporal    bone  —  Internal 

50. 

Ligaments  of  the  pelvis  and 

surface    .         -         -         . 

38 

hip-joint - 

115 

16. 

Sphenoid    bone  —  Superior 

51. 

Id.             id.       -        -         - 

116 

surface    ..... 

41 

52. 

Ligaments  ofthe  sternal  end 

17. 

Sphenoid   bone — Antero-in- 

of  the  clavicle  and  costal 

ferior  surface  - 

42 

cartilages 

119 

18. 

Ethmoid  bone    - 

44 

53. 

Ligaments    of  the    scapula 

19. 

Superior  maxillary  bone 

46 

and  shoulder-joint   - 

120 

20. 

Palate  bone — Internal  sur- 

54. 

Ligaments   of   the   elbow ; 

face         .... 

49 

internal  view  - 

122 

21. 

Palate  bone — External  sur- 

55. 

Id.             external  view 

122 

face         .         -         .         . 

50 

56. 

Ligaments  of  the  wrist  and 

22. 

Inferior  maxillary  bone 

52 

hand        .... 

124 

23. 

Skull,  anterior  view    - 

56 

57. 

Synovial  membranes  of  the 

24. 

Base  of  the  skull ;  internal 

wrist       .... 

126 

view       .         .         .         - 

56 

58. 

Knee-joint ;  anterior  view  - 

130 

25. 

Base  of  the  skull ;  external 

59. 

Id. ;  posterior  view     . 

131 

view        .... 

59 

60. 

Id. ;  internal  view 

132 

26. 

Os  hyoides 

70 

61. 

Id.;  reflections  ofthe  syno. 

27. 

Thorax      .... 

71 

vial  membrane 

132 

28. 

Scapula      .... 

74 

62. 

Ankle-joint ;  internal  view 

135 

29. 

Humerus  .... 

76 

63. 

Id.         external  view  - 

135 

30. 

Ulna  and  radius 

78 

64. 

Id.        posterior  view 

137 

31. 

Bones  of  the  carpus  ;  poste- 

65. 

Ligaments  ofthe  sole  ofthe 

rior  view 

79 

foot         .... 

138 

32. 

Hand ;  anterior  view 

83 

66. 

Minute  structure  of  muscle 

141 

33. 

Os  innominatum 

85 

67. 

Minute  structure  of  muscle 

142 

34. 

Femur ;  anterior  view 

90 

68. 

MuKcIes  of  the  face    - 

145 

TABLE  OF  ILLUSTRATIONS, 


69.  Muscles  of  the  ovbit  - 

70,  Pterygoid  muscles 

7J.  Muscles  of  the  neck;  super- 
ficial and  deep 

72.  Muscles  of  the  tongue 

73.  Muscles  of  the  pharynx 

74.  Muscles  of  the  soft  palate   - 

75.  Muscles  of  the  prEevertebral 

region     .         .         .         - 

76.  Muscles   of  the  back;   1st, 

2d,  and  3d  layer 

77.  Muscles  of  the  back  ;  deep 

layer       .         .         .         - 

78.  Muscular   of   the    anterior 

aspect  of  the  trunk  - 

79.  Muscles  of  the  lateral  aspect 

of  the  trunk     - 

80.  Diaphragm         .         .         - 

81.  Muscles  of  the  perineum     - 

82.  Muscles  of  the  anterior  hu- 

meral region  - 

83.  Triceps  extensor  cubiti 

84.  Superficial  layer  of  muscles 

of  the  anterior  aspect  of 
the  fore-arm    - 

85.  Deep  layer  of  muscles    of 

the  anterior  aspect  of  the 
fore-arm  ... 

86.  Superficial   layer   of  mus- 

cles ;    posterior  aspect  of 
the  fore-arm    -         -         . 

87.  Deep  layer ;  posterior  aspect 

of  the  fore-arm 

88.  Muscles  of  the  hand,  ante- 

rior aspect      .         -         - 

89.  Muscles  of  the  gluteal  re- 

gion, deep  layer 

90.  Muscles  of  the  anterior  and 

internal  femoral  region    - 

91.  Muscles  of  the  gluteal  and 

posterior  femoral  region  - 

92.  Muscles    of   the     anterior 

tibial  region    .         -         - 

93.  Muscles    of   the    posterior 

tibial    region,    superficial 
layer       .... 

94.  Muscles    of   the    posterior 

tibial  region,  deep  layer  . 

95.  Muscles  of  the  sole  of  the 

foot:     1st  layer 

96.  "     "      2d  layer 

97.  Section  of  the  neck,  show- 

ing the  distribution  of  the 
deep  cervical  fascia 

98.  Transverse   section   of  the 

pelvis,  showing  the  distri- 
bution of  the  fasciae 

99.  Deep  perineal  fascia  - 

100.  Distribution    of    the    deep 

perineal  fascia,  side  view 

101.  Distribution  of  the  fasciaj ; 

at  the  femoral  arch 

102.  The   great  vessels   of   the 

chest       -         .         -         - 

103.  Brandies   of   the    external 

carotid  artery 


148 

•  104. 

Branches  of  the  subclavian 

155 

artery     -         -         .         . 

283 

105. 

The  circle  of  AVillis   . 

286 

159 

106. 

Axillary  and  brachial  arte- 

164 

ries         .... 

290 

167 

107. 

Arteries  of  the  fore-arm — 

168 

Radial  and  ulnar     - 

294 

108. 

Branches  of  the  abdominal 

170 

aorta       .         .         .         - 

299 

109. 

Cceliac  axis  with  its  bran- 

175 

ches         .... 

301 

110. 

The     superior     mesenteric 

178 

artery     .         -         .         . 

302 

111. 

The  inferior  mesenteric  ar- 

187 

tery         .         -         -         . 

304 

112. 

The    internal    iliac   artery 

192 

with  its  branches     - 

307 

194 

113. 

The    arteries    of   the    peri- 

198 

neum      -         -         -         . 

308 

114. 

The  femoral  artery  with  its 

207 

branches          .         -         . 

313 

209 

115. 

The  anterior  tibial  artery  - 

321 

116. 

Posterior  tibial  and  peroneal 

artery     .... 

321 

211 

117. 

Arteries  of  the  sole  of  the  foot 

324 

118. 

Sinuses  of  the  dura  mater  - 

332 

119. 

Sinuses  of  the  base  of  the 

211 

skull        .... 

334 

120. 

Veins   and   nerves   of    the 

bend  of  the  elbow    . 

337 

215 

121. 

Veins  of  the  trunk  and  neck 

340 

122. 

The  portal  vein 

345 

215 

123. 

The  thoracic  duct 

355 

124. 

The  lateral  ventricles  of  the 

219 

cerebrum         ... 

368 

125, 

Longitudinal  section  of  the 

225 

brain       .... 

372 

126. 

Base  of  the  brain 

379 

228 

127. 

Distribution  of  the  fibres  of 

the  brain 

380 

233 

128. 

Nerves  of  the  tongue  and 

neck        .... 

388 

237 

129. 

Facial  nerve  and  superficial 

cervical  nerves 

392 

130 

Origin  and  distribution  of 

237 

the  eighth  pair  of  nerves 

396 

131 

Branches   of   the    trifacial 

239 

nerve        .... 

400 

132. 

Axillary  plexus  and  nerves 

242 

of  the  upper  extremity     - 

409 

242 

133. 

Lumbar  and  sacral  plexus, 
with   the    nerves    of   the 

lower  extremity 

416 

248 

134 

The  cranial  ganglia  of  the 

sympathetic  nerve  - 

426 

135 

Fibro-cartilages  of  the  nose 

436 

252 

136. 

Longitudinal  section  of  the 

253 

globe  of  the  eye 

439 

137 

A  transverse  section  of  the 

254 

globe  of  the  eye 

442 

138. 

Another   transverse  section 

257 

of  the  globe  of  the  eye 

443 

139 

A  diagram  of  the  ear  - 

453 

264 

140 

Anatomy  of  the  cochlea 

458 

141 

Osseous    and    membranous 

271 

labyrinth  of  the  car 

460 

TABLE  or  ILLUSTRATIONS. 


142. 

Tlie  anatomy  of  tlie  skin    - 

464 

158 

143 

Anatomy  of  tlie  skin  - 

465 

159. 

144. 

The  heart  -         -         .         . 

470 

14.5. 

Muscles  of  the  larynx 

482 

146. 

MuTscles  of  the  larynx 

482 

160. 

147. 

Anatomy  of  the  lungs  and 

161. 

heart       -         .         -         - 

487 

148. 

The  peritoneum 

491 

162. 

149. 

The  pharynx 

499 

163. 

150. 

Anatomy    of   the    stomach 

and  duodenum 

501 

164. 

151. 

Columns  and  pouches  of  the 

165. 

rectum    .         .         -         - 

506 

166. 

152. 

Muscular  coat  of  the  rectum 

510 

167. 

153. 

The  liver;  its  upper  surface 

511 

154. 

The  liver;  its  under  surface 

513 

168. 

155. 

Lobules  of  the  liver    - 

514 

156. 

Section  of  the  kidney 

527 

169. 

157. 

A  side  view  of  the  viscera 

170. 

of  the  male  pelvis    - 

528 

Neck  of  the  bladder    - 

A    posterior    view   of   the 

bladder      and      vesiculsB 

seminales         ... 
Anatomy  of  the  urethra 
Transverse    section    of  the 

testicle    .         .         -         - 
Anatomy  of  the  testis 
A  side  view  of  the  viscera 

of  the  female  pelvis 
Fcetal  circulation 
Section  of  the  thymus  g-land 
Ducts  of  the  thymus  gland 
Descent  of  the  testis  in  the 

fcetus       .... 
Descent  of  the  testis  in  the 

foetus       .... 
Vignette, 
Faces  title,  Time  and  Death. 


331 


533 
537 

540 
542 

545 
553 
556 

557 

561 
561 


SYSTEM  OF  HUMAN  ANATOMY. 


CHAPTER  I. 

OSTEOLOGY. 


The  bones  are  the  organs  of  support  to  the  animal  frame ;  they 
give  firmness  and  strength  to  the  entire  fabric,  afford  points  of  con- 
nection to  the  numerous  muscles,  and  bestow  individual  character 
upon  the  body.  In  the  limbs  they  are  hollow  cylinders,  admirably 
calculated  by  their  conformation  and  structure  to  resist  violence  and 
support  weight.  In  the  trunk  and  head,  they  are  flattened  and  arched, 
to  protect  cavities  and  provide  an  extensive  surface  for  attachment. 
In  some  situations  they  present  projections  of  variable  length,  which 
serve  as  levers  ;  and  in  others  are  grooved  into  smooth  surfaces, 
which  act  as  trochlece  or  pulleys  for  the  passage  of  tendons.  More- 
over, besides  supplying  strength  and  solidity,  they  are  equally  adapted, 
by  their  numerous  divisions  and  mutual  apposition,  to  fulfil  every 
movement  which  may  tend  to  the  preservation  of  the  creature,  or 
be  conducive  to  his  welfare. 

According  to  the  latest  analysis  by  Berzelius,  bone  is  composed 
of  about  one-third  of  animal  substance,  which  is  almost  completely 
reducible  to  gelatine  by  boiling,  and  of  earthy  matters ;  in  the  fol- 
lowing proportions : — 


Cartilage         .... 

.     32-17  parts. 

Blood-vessels       .... 

113 

Phosphate  of  lime  . 

.     51-04 

Carbonate  of  lime 

11-30 

Fluate  of  lime 

.       2- 

Phosphate  of  magnesia 

1-16 

Soda,  chloride  of  sodium 

1-20 

100-00 

Bones  are  divisible  into  four  classes :  Long,  short,  Jlat,anc\  irregular. 

The  long  bones  are  found  principally  in  the  limbs,  and  they  con- 
sist of  a  shaft  and  two  extremities.  The  shaft  is  cylindrical  or 
prismoid  in  form,  dense  and  hard  in  texture,  and  hollowed  in  the 
interior  into  a  medullary  canal.  The  extremities  are  broad  and  ex- 
panded, to  articulate  with  adjoining  bones ;  and  cellular  or  cancel- 

3 


18  STRUCTURE  OF  BONE. 

lous  in  their  internal  structure.  Upon  the  exterior  of  the  bone  are 
processes  and  rough  surfaces  for  the  attachment  of  muscles,  and 
fora.mina  for  the  transmission  of  vessels  and  nerves,  and  the  attach- 
ment of  ligaments.  The  character  of  long  bones  is,  therefore,  their 
general  type  of  structure  and  their  divisibility  into  a  central  portion 
and  extremities,  and  not  so  much  their  length ;  for  there  are  some 
long  bones — as  the  second  phalanges  of  the  toes — which  are  less 
than  a  quarter  of  an  inch  in  length,  and  are  almost  equal,  and  in 
some  instances,  exceed  in  breadth  their  longitudinal  axis.  The  long 
bones  are,  the  clavicle,  humerus,  radius  and  ulna,  femur,  tibia,  and 
fibula,  metacarpal  bones,  metatarsal,  phalanges  and  ribs. 

S/io7't*  bones  are  such  as  have  no  predominance  of  length  or 
breadth,  but  are  irregularly  cuboid  in  form  :  they  are  spongy  in  in- 
ternal texture,  and  invested  by  a  thin  crust  of  condensed  osseous  tissue. 
The  short  bones  are,  the  vertebrae,  coccyx,  carpal  and  tarsal  bones, 
patellae,  and  sesamoid  bones. 

Flat  bones  are  composed  of  tv\ro  layers  of  dense  bone  with  an  inter- 
mediate cellular  structure,  and  are  divisible  into  surfaces,  borders, 
angles,  and  processes.  They  are  adapted  to  enclose  cavities  ;  have 
processes  upon  their  surface  for  the  attachment  of  muscles ;  and  are 
perforated  by  foramina,  for  the  passage  of  nutrient  vessels  to  their 
cells,  and  for  the  transmission  of  vessels  and  nerves.  They  articulate 
with  long  bones  by  means  of  smooth  surfaces  plated  with  cartilage, 
and  with  each  other  either  by  cartilaginous  substance,  as  at  the 
symphysis  pubis ;  or  by  suture,  as  in  the  bones  of  the  skull.  The 
two  condensed  layers  of  the  bones  of  the  skull  are  named  tables  ; 
and  the  intermediate  cellular  structure  diploe.  The  flat  bones  are 
the  occipital,  parietal,  frontal,  nasal,  lachrymal,  vomer,  sternum, 
scapulae,  and  ossa  innominata. 

Irregular  bones  are  those  which  are  not  distinctly  referrible  to 
either  of  the  above  heads ;  but  present  a  mixed  character,  being 
partly  short  and  partly  flat  in  their  conformation.  The  bones  of  this 
class  are,  the  temporal,  sphenoid,  ethmoid,  superior  maxillary,  in- 
ferior maxillary,  palate,  inferior  turbinated  bones,  os  hyoides,  and 
sacrum. 

Structure. — In  structure,  bone  is  composed  of  lamellae,  which  are 
concentric  in  long,  and  parallel  in  flat  bones.  Between  the  lamellee 
are  situated  numerous  small  longitudinal  canals  and  minute  oval 
corpuscules.  The  longitudinal  canals  (canals  of  Havers)  contain  me- 
dullary substance  and  vessels,  and  communicate  with  each  other, 
and  with  the  medullary  canal  or  cells.  Each  longitudinal  canal  is 
surrounded  by  a  scries  of  concentric  lamellae,  and  between  these 
lamellae,  as  well  as  between  the  lamellae  which  constitute  the  great 
medullary  canal  of  the  bone,  the  oval  corpuscules  are  situated.  In 
the  extremities  of  long,  in  short,  and  in  flat  bones,  the  cells  repre- 
sent the  Haversian  canals,  and  are  each  surrounded  by  concentric 

*  Wilson's  classep  of  short  and  irregular  bones  arc  usually  included  in  the  title  ossa 
r.raasa  or  thick  bones.     G. 


STRUCTURE  OF  BONE. 


19 


lamellae ;  indeed,  the  medullary  canal  of  long  bones  may  be  con- 
sidered as  a  single  Haversian  canal  exceedingly  dilated.  The  oval 
corpuscules*  are  minute  cells,  from  which  are  given  off  a  number  of 
radiating  and  branching  tubuli,t  which  anastomose  with  the  cor- 
responding tubuli  of  neighbouring  cells.  The  cells  and  tubuli  are 
filled  with  calcareous  substance:  hence  they  have  been  named 
calcigerous  cells  and  tubuli. 

Deutsch,  in  his  excellent  researchesj  on  the  minute  structure  of 
bone,  has  described  certain  radiating  lines  which  traverse  the  thick- 
ness of  the  concentric  lamellae.  They  are  thus  referred  to  by 
Miiller.§  "  It  is  very  remarkable  that  the  thickness  of  the  lamellse 
is  traversed  by  numerous  lines  which  are  separated  by  very  small 
intervals,  and  which  correspond  in  length  to  the  thickness  of  the 
lamellas,  namely,  ^lo^h  of  a  Une.  Deutsch  supposes  these  lines  to 
be  tubes  in  which  the  calcareous  matter  of  the  bones  is  deposited(?) ; 
if  one  lamella  be  separated  from  another  the  ends  of  the  lines  are 
seen,  he  says,  of  a  triangular  form.  The  existence  of  these  fine 
tubes  (?)  was  hitherto  quite  unknown ;  but  it  is  not  probable  that 
they  serve  for  the  reception  of  the  calcareous  matter,  for  the  first 
appearance  of  ossification  is  in  the  form  of  a  microscopic  net- 
work !"||  Having  been  engaged  during  the  past  summer  (1841), 
and  being  still  occupied  with  the  investigation  of  the  minute  struc- 
sture  of  bone,  I  have  had  the  good  fortune  to  discover  the  true 
nature  of  the  lines  thus  alluded  to  by  Deutsch  and  Miiller.  I  have 
found  that  the  corpuscules  of  Purkinje  are  arranged  very  differently 
in  different  kinds  of  bones  ;  that  in  flat  bones,  and  in  the  thin  lamella 
of  cellular  bones,  they  exist  in  great  numbers,  are  of  considerable 
size,  and  are  disposed  with  no  regularity.  Their  tubuU  are  short, 
tapering,  and  tortuous,  and  proceed  irregularly  from  every  part  of 
the  surface  of  the  corpuscules.  In  the  long  bones,  the  corpuscules  are 
apparently  smaller  than  the  preceding,  they  are  oval  and  flattened, 
and  lie  between  the  concentric  lamellse.  Their  tubuli  are  long  and 
only  slightly  undulating,  and  diminish  very  gradually  towards  their 
termination,  where  they  communicate  with  the  tubuli  of  other  cor- 

*  Discovered   by   Purkinje.     They   are  about    goth   of  a  line  tlirough  their  long 

diameter. 

+  Discovered  by  Mttller.     They  are  very  distinct.     Their  larger  trunks  are  about 

__! th  of  a  line  in  diameter. 

^0  00 

t  De  penitiori  ossium  structura  observationes.     Dissert,  inaug.  Vratisl. 

§  Physiology,  Translation,  p.  378. 

II  In  reference  to  this  question,  Dr.  Bayly,  the  translator  of  Miiller,  observes, 
"  Miescher  does  not  confirm  Deulsch's  statement  as  to  the  still  more  minute  tubes 
traversing  the  concentric  lamella;,  although  he  perceived  the  radiated  appearance 
around  the  larger  canals,  w^hich  was  produced  by  dots  or  short  lines,  which  do  not 
occupy  the  whole  thickness  of  each  lamella.  Some  of  the  lines  appear  to  traverse 
more  than  one  lamella,  though  the  majority,  as  Miescher  describes,  are  very  short. 
They  appear  more  like  the  separations  between  the  granules  of  cartilage  that  form  tJie 
lamella;  than  distinct  tubes."  Dr.  Bayly  has  given  the  figure  of  a  transverse 
section  of  an  Haversian  canal,  in  which  Deutsch  and  Miescher's  views  are  clearly 
illustrated. 


20 


STRUCTURE  OF  BONE. 


Fiff.  1.* 


pusciiles  or  with  the  corpiiscules  themselves.     Among  the  concen- 
tric lamellas  of  the  Haversian  canals,  the  tubuli  are  given  off  from 

the  surfaces,  lying  in  contact 
vs^ith  the  lamellae,  and  they 
proceed  straight  through  the 
lamellae  in  two  directions, 
inwards  towards  the  area  of 
the  Haversian  canal,  or  out- 
wards towards  the  outer- 
most lamellae.  If  in  their 
course  the  tubuli  meet  with 
another  corpuscule,  they  ter- 
minate in  it  or  communicate 
with  its  branches ;  but  the 
direct  course  of  the  tubuli 
towards  the  centre  is  never 
interfered  with.  So  evident 
is  the  tendency  of  all  the 
tubuli  to  attain  the  centre, 
that  in  several  corpuscules 
situated  between  the  outer- 
most lamellae,  I  have  ob- 
served the  tubuli  from  the  external  surface  to  curve  around  the  ex- 
tremities of  the  corpuscule,  in  order  to  proceed  with  those  given  off 
from  the  internal  surface,  to  their  central  destination.  From  their 
general  appearance  in  relation  to  the  lamellae,  these  tubuli  seem  to 
me  to  deserve  the  title  of  converging  tubuli;  they  all  proceed 
towards  the  central  canal,  and  those  which  reach  that  destination 
terminate  upon  its  internal  surface.  The  trunks  of  the  tubuli  not 
unfrequently  give  off  one  or  two  branches.  As  regards  their  form, 
the  tubuli  are  undoubtedly  cylindrical,  and  they  probably  contain 
calcareous  substance,  as  do  the  calcigerous  tubuli  described  by 
MuUer. 

The  lines  remarked  by  Deutsch  are,  therefore,  according  to  my 
observations,  cylindrical  tubuli,  traversing  the  concentric  lamellae 
of  bone,  communicating  with  the  corpuscules,  and  with  the  cavity 
of  the  Haversian  canal,  and  identical  with  the  calcigerous  tubuU  of 
Miiller. 

In  the  fresh  state  bones  are  invested  by  a  dense  fibrous  mem- 
brane, the  'periosteum,  covering  every  part  of  their  surface  with  the 
exception  of  the   articular  extremities,   which   are  coated   by   a 

*  Minute  structure  of  bono,  drawn  with  the  microscope  from  nature,  by  Bagg. 
M.'ifrnified  300  diameters.  1.  One  of  the  Haversian  canals  surrounded  by  its  concentric 
lamelifc.  The  corpuscules  are  seen  between  the  lamella) ;  but  the  converging  tubuli 
are  omitted.  2.  An  Haversian  canal  with  its  concentric  lamellfE,  Purkinjean  corpus- 
cules, and  converging  tubuli.  3.  The  area  of  one  of  the  canals.  4,  4.  Direction  of  the 
lamellfE  of  the  great  medullary  canal.  Between  the  lamella  at  the  upper  part  of  the 
figure,  several  very  long  corpuscules  with  their  tubuli  are  seen.  In  the  lower  part  of 
the  figure,  the  outlines  of  three  other  canals  are  given,  in  order  to  show  their  form  and 
mode  of  arrangement  in  the  entire  bone. 


DEVELOPEMENT  OF    BONE.  21 

thin  layer  of  cartilage.  The  periosteum  of  the  bones  of  the  skull  is 
termed  'pericranium ;  and  the  analogous  membrane  of  external 
cartilages,  perichondrium.  Lining  the  interior  of  the  medullary 
canal  of  long  bones,  the  Haversian  canals,  the  cells  of  the  cancelli, 
and  the  cells  of  short,  flat,  and  irregular  bones,  is  the  medullary 
membrane,  which  acts  as  an  internal  periosteum.  It  is  through  the 
medium  of  the  vessels  supplying  these  membranes  that  the  changes 
required  by  nutrition  occur  in  bones,  and  the  secretion  of  medulla 
into  the  interior  is  effected.  The  medullary  canal  of  long  bones, 
and  the  cells  of  other  bones,  are  filled  with  a  yellowish  oily  substance 
— the  medulla,  which  is  contained  in  a  loose  cellular  tissue  formed 
by  the  medullary  membrane. 

Developement  of  Bone. — The  earliest  trace  of  skeleton  in  the  human 
embryo  is  observed  in  the  presence  of  semi-opaque  lines,  which 
are  seen  through  the  transparent  embryonic  mass.  This  trace  is 
composed  of  a  consistent  granular  jelly,  and  constitutes  the  gelatinous 
state  of  osteo-genesis.  In  the  second  or  cartilaginous  state,  the 
semi-opaque  jelly  becomes  dense,  transparent,  and  homogeneous,  the 
change  taking  place  from  the  surface  towards  the  centre,  and  con- 
stituting cartilaginijication.  In  the  third  stage,  the  cartilage  is  tra- 
versed by  vessels  carrying  red  blood,  which  proceed  from  the  fibrous 
investment  and  ramify  in  its  interior.  The  cartilage  immediately 
surrounding  these  vessels,  becomes  opaque  and  of  a  yellowish  red 
colour.  In  the  fourth  stage,*  the  earthy  constituents  are  attracted 
from  the  blood  by  the  opaque  cartilage,  which  becomes  altered  in 
character,  and  shoots  into  the  transparent  cartilage  in  the  form  of 
reddish  gray  fibres,  which  communicate  with  each  other  at  acute 
angles  and  constitute  an  areolar  osseous  tissue.  This  is  the  state  of 
ossification.  The  succeeding  changes  are  those  of  condensation  and 
the  formation  of  cells,  the  Haversian  and  medullary  canals. 

Cartilaginification  is  complete  in  the  human  embryo  at  about  the 
sixth  week ;  and  the  first  point  of  ossification  is  observed  in  the 
clavicle  at  about  the  seventh  week.  Ossification  commences  at  the 
centre,  and  thence  proceeds  towards  the  surface ;  in  flat  bones  the 
osseous  tissue  radiates  between  two  membranes  from  a  central 
point  towards  the  periphery,  in  short  bones  from  a  centre  towards 
the  circumference,  and  in  long  bones  from  a  central  portion,  diaphysis, 
towards  a  secondary  centre,  epiphysis,  situated  at  each  extremity. 
Large  processes,  as  the  trochanters,  are  provided  with  a  distinct 
centre,  which  is  named  apophysis. 

The  growth  of  the  bone  in  length  takes  place  at  the  extremity  of 
the  diaphysis,  and  in  bulk  by  fresh  deposition  on  the  surface ;  while 
the  medullary  canal  is  formed  and  increased  by  absoi-ption  from 
within. 

The  period  of  ossification-\  is  different  in  different  bones ;  the  order 
of  succession  may  be  thus  arranged : — 

*  The  spot  at  which  this  stage  commences  is  called  the  piincttmi  of^xi/icntioiiix.     f». 
t  Burdach,  Physiologic. 


22 


DEVELOPEMENT  OF  BONE. 


From  the  sixth  to  the  eightli  week,  ossification  commences  first 
in  the  clavicle,  then  in  the  lower  jaw,  upper  jaw,  and  femur. 

From  the  eighth  to  the  tenth  week,  in  the  frontal,  occipital, 
humerus,  radius  and  ulna,  tibia  and  fibula,  scapulae,  ribs. 

From  the  tenth  to  the  twelfth  week,  in  the  temporal,  sphenoid, 
malar,  parietal,  palate,  nasal,  vertebras,  metacarpus,  metatarsus,  last 
phalanges  of  the  hands,  and  feet. 

From  the  third  to  the  fourth  month,  in  the  vomer,  first  and  second 
phalanges,  ossa  innominata. 

From  the  fourth  to  the  fifth  month,  in  the  ethmoid,  lachrymal  and 
spongy  bones. 

From  the  fifth  to  the  sixth  month,  in  the  sternum,  carpus,  and 
tarsus. 

From  the  sixth  to  the  tenth  month  in  the  os  hyoides,  coccyx,  and 
cuboid  bone. 

At  one  year,  in  the  coracoid  process  of  the  scapula,  os  magnum, 
OS  unciforme,  and  internal  cuneiform  bone. 

At  three  years,  in  the  patella,  and  carpal  cuneiform  bone. 

At  four  years,  in  the  external  and  middle  cuneiform  bone. 

At  five  years,  in  the  tarsal  scaphoid  bone,  trapezium,  and  semi- 
lunare. 

At  eight  years,  in  the  carpal  scaphoid. 

At  nine,  in  the  trapezoid,  and  at  the  twelfth  year,  in  the  pisiform 
bone. 

The  ossicula  auditus  are  the  only  bones  completely  ossified  at 
birth. 

The  entire  osseous  framework  of  the  body  constitutes  the  skeleton, 
which  in  the  adult  man  is  composed  of  two  hundred  and  forty-six 
distinct  bones.     They  may  be  thus  arranged : — 

Cranium 

Ossicula  auditus 

Face     .... 

Teeth 

Vertebral  column 

Os  hyoides,  sternum,  and  ribs 

Upper  extremities 

Pelvis 

Lower  extremities 

Sesamoid  bones 

246 

The  skeleton  is  divisible  into  1st.  The  vertebral  column  or  central 
axis.  2.  The  cranium  and  face  or  superior  dcvclopemcnt  of  the 
central  axis.  3.  The  hyoid  arch.  4.  The  thoracic  arch  and  upper 
extremities.     .0.  The  ]r)clvic  arch  and  lower  extremities. 

*  Wilson  describes  throe  bones  to  tlic  car  viz :  malleus,  inr.us  and  stapes,  making  the 
orhicnlare  of  other  anatomistw  a  part  of  the  staprs.  lie  also  countR  thirty-two  teeth 
in  this  enumeration,  which  is  not  common.     G. 


.       8 

6* 

.     14 

32 

.     24 

s     ...         26 

.     64 

4 

.     60 

8 

VERTEBRAL  COLUMN.  23 


VERTEBRAL  COLUMN. 


The  Vertebral  column  is  the  first  and  only  rudiment  of  internal 
skeleton  in  the  lower  Vertebrata,  and  constitutes  the  type  of  that 
great  division  of  the  animal  kingdom.  It  is  also  the  first  developed 
portion  of  the  skeleton  in  man,  and  the  centre  around  which  all  the 
other  parts  are  produced.  In  its  earliest  formation  it  is  a  simple 
cartilaginous  cylinder,  surrounding  and  protecting  the  primitive 
trace  of  the  nervous  system ;  but,  as  it  advances  in  growth  and  or- 
ganization, it  becomes  divided  into  distinct  pieces,  which  constitute 
vei'tehrcr. 

The  vertebrsB  are  divided  into  true  and  false.  The  true  vertebrse 
are  twenty-four  in  number,  and  are  classified  according  to  the  three 
regions  of  the  trunk  which  they  occupy,  into  the  cervical,  dorsal,  and 
lumbar.  The  false  vertebrae  consist  of  nine  pieces  united  into  two 
bones, — the  sacrum  and  coccyx.  The  arrangement  of  the  vertebrae 
may  be  better  comprehended  by  means  of  the  accompanying  table : — 

C  7  Cervical, 

True  vertebrse  24     ^  12  Dorsal, 

(  5  Lumbar. 

False  vertebrse  9     (  5  Sacrum, 

I  4  Coccyx. 

Characters  of  a  Vertebra. — A  vertebra  consists  of  a  body,  two 
laminae,  a  spinous  process,  two  transverse  processes,  and  four  ar- 
ticular processes.  The  body  is  the  solid  part  of  the  vertebra ;  and 
by  its  articulation  with  adjoining  vertebrae,  gives  strength  and  sup- 
port to  the  trunk.  It  is  flattened  above  and  below,  convex  in  front, 
and  slightly  concave  behind.  Its  anterior  surface  is  constricted 
around  the  middle,  and  pierced  by  a  number  of  small  openings 
which  give  passage  to  nutritious  vessels.  Upon  its  posterior  surface 
is  a  singular  irregular  opening,  or  several,  for  the  exit  of  the  vence 
basis  vertebrcB  or  vertebral  sinuses. 

The  lamincB  commence  upon  the  sides  of  the  posterior  part  of  the 
body  of  the  vertebra  by  two  pedicles ;  they  then  expand,  and 
arching  backwards,  enclose  a  foramen  which  serves  for  the  protec- 
tion of  the  spinal  cord.  The  upper  and  lower  borders  of  the  laminae 
are  rough  for  the  attachment  of  the  ligamenta  subflava.  The  con- 
cavities above  and  below  the  pedicles  are  the  intervertebral  notches. 
The  spinous  process  stands  backwards  from  the  angle  of  union  of 
the  laminae  of  the  vertebra.  It  is  the  succession  of  these  projecting 
processes  along  the  middle  line  of  the  back,  that  has  given  rise  to 
the  common  designation  of  the  vertebral  column — the  spine.  The 
use  of  the  spinous  process  is  for  the  attachment  of  muscles.  The 
transverse  processes  project  one  at  each  side  from  the  laminae  of  the 
vertebra ;  they  are  intended  for  the  attachment  of  muscles.  The 
articular  processes,  four  in  number,  stand  upwards  and  downwards 
from  the  lamina3  of  the  vertebras  to  articulate  with  the  vertebra 
above  and  below. 


<!4  CERVICAL  VERTEBRA. 

Cervical  Vertebrce. — In  a  cervical  ver- 
Fig-  2*  tebra  the  body  is  smaller  than  in  the  other 

regions  ;  it  is  thicker  before  than  behind, 
broad  from  side  to  side,  concave  on  the 
upper  surface  and  convex  below  ;  so  that 
when  articulated,  the  vertebrse  lock  the 
one  into  the  other.  The  lamince  are 
broad  and  long,  and  the  included  foramen 
large  and  triangular.  The  superior  and 
inferior  intervertebral  notches  are  nearly 
equal  in  depth.  The  spinous  process  is 
short  and  bifid  at  the  extremity,  increas- 
ing in  length  from  the  fourth  to  the  seventh.  The  transverse  processes 
are  also  short  and  bifid,  and  grooved  along  the  upper  surface  for  the 
cervical  nerves.  Through  the  base  of  the  transverse  process  is  the 
vertebral  foramenf  for  the  passage  of  the  vertebral  artery  and  vein, 
and  vertebral  plexus  of  nerves.J  The  transverse  processes  in  this 
region,  are  formed  by  two  small  developements,  which  proceed,  the 
one  from  the  side  of  the  body,  the  other  from  the  pedicle  of  the 
vertebra,  and  unite  by  their  extremities  so  as  to  enclose  the  circular 
area  of  the  vertebral  foramen.  The  anterior  of  these  developements 
is  the  rudiment  of  a  cervical  rib  ;  and  the  posterior,  the  true  trans- 
verse process  analogous  to  the  transverse  processes  of  the  vertebrse 
in  the  dorsal  and  lumbar  regions.  The  extremities  of  these  de- 
velopements constitute  the  two  tubercles  of  the  transverse  process. 

The  articular  processes  are  oblique  ;  the  superior  looking  upwards 
and  backwards ;  and  the  inferior,  downwards  and  forwards. 

There  are  three  peculiar  vertebras  in  the  cervical  region : — The 
first  or  atlas ;  the  second  or  axis  ;§  and  the  seventh  or  vertebra 
prominens. 

The  Mlas  (named  from  supporting  the  head)  is  a  simple  ring  of 
bone  without  body,  and  composed  of  arches  and  processes.  The 
anterior  arch  has  a  tubercle  upon  its  anterior  surface,  for  the  attach- 
ment of  the  longus  colli  muscle ;  and  upon  its  posterior  part  is  a 
smooth  surface,  for  the  articulation  of  the  odontoid  process  of  the  axis. 
The  posterior  arch  is  longer  and  more  slender  than  the  anterior, 
and  flattened  from  above  downwards ;  at  its  middle  is  a  rudimentary 
spinous  process  ;  and  upon  its  upper  surface,  near  the  articular  pro- 
cesses, a  shallow  groove||  at  each  side,  which  represents  a  superior 
intervertebral  notch,  and  supports  the  vertebral  artery,  previously 

*  A  central  cervical  vertebra,  seen  upon  its  upper  surface.  1.  The  body,  concave  in 
the  middle,  and  rising'  on  each  side  into  a  sharp  lidtre.  2.  The  lamina.  3.  The  pedicle 
rendered  concave  by  the  superior  intervertcliral  notch.  4.  The  bifid  spinous  process. 
.5.  The  bifid  transverse  process.  6.  Tlie  foramen  for  the  vertebral  artery.  7.  The 
superior  articular  process.     8.  The  inferior  articular  process. 

+  There  is  an  objection  to  this  name,  as  it  is  liable  to  be  confounded  with  the  foramen 
for  the  spinal  medulla.     G. 

t  SomctimoK,  as  in  a  vertebra  now  before  me,  a  small  additional  opening  exists  by 
the  side  of  the  vertebral  foramen,  in  which  case  it  is  traversed  by  a  second  vein. 

^  Usually  called  verlchra  dentata.     G. 

II  This  groove  is  sometimes  converted  into  a  foramen, 


ATLAS  AND  AXIS. 


25 


Fiff.  3.* 


to  its  passage  through  the  dura  mater,  and  the  first  cervical  nerve. 
The  intervertebral  notches  are  peculiar  from  being  situated  behind 
the  articular  processes  instead  of 
before  them,  as  in  the  other  verte- 
brae. The  transverse  processes  are 
remarkably  large  and  long,  and 
pierced  by  the  foramen  for  the 
vertebral  artery.  The  arUcidar 
processes  are  situated  upon  the 
most  bulky  and  strongest  parts  of 
the  atlas.  The  superior  are  oval 
and  concave,  and  look  invv^ards, 
so  as  to  form  a  kind  of  cup  for  the  condyles  of  the  occipital  bone, 
and  are  adapted  to  the  nodding  movements  of  the  head ;  the  inferior 
are  circular,  and  nearly  horizontal,  to  permit  of  the  rotary  move- 
ments. Upon  the  inner  face  of  the  lateral  mass  which  supports  the 
articular  processes,  is  a  small  tubercle  at  each  side,  into  which  the 
extremities  of  the  transverse  ligament  are  attached,  a  ligament 
which  divides  the  ring  of  the  atlas  into  two  unequal  segments ;  the 
smaller  for  receiving  the  odontoid  process  of  the  axis,  and  the  latter 
to  give  passage  to  the  spinal  cord  and  its  membranes. 

The  Axis  is  named  from  having  a  process  upon  which  the  head 
turns  as  on  a  pivot.  The  body  is  of  a  large  size,  and  supports  a 
strong  process, — the  odontoid, — which  rises  perpendicularly  from 
its  upper  surface.  The  odontoid  'process  (processus  dentatus)  pre- 
sents two  articulating  surfaces ;  one  on  its  anterior  face,  to  articu- 
late with  the  anterior  arch  of  the  atlas ;  the  other  on  its  posterior 
face,  for  the  transverse  ligament.  Upon  each  side  of  its  apex  is  a 
rough  depression,  for  the  attachment  of  the 
alar,  or  moderator  ligaments.  The  kanince 
are  large  and  strong,  and  unite  posteriorly  to 
form  a  long  and  projecting  spinous  process. 
The  transvprse  processes  are  quite  rudimen- 
tary, not  bifid,  and  project  only  so  far  as  to 
enclose  the  vertebral  foramen,  which  is  di- 
rected obliquely  outwards  instead  of  perpen- 
dicularly as  in  the  other  vertebrjB.  The 
superior  articulating  processes  are  situated 
upon  the  body  of  the  vertebra  on  each  side  of  the  odontoid  process. 


Fig.  4.t 


*  The  upper  surface  of  the  atlas.  1.  The  anterior  tubercle  projecting  from  the 
anterior  arch.  2.  The  articular  surface  for  the  odontoid  process  upon  the  posterior  sur- 
face of  the  anterior  arch.  3.  The  posterior  arch,  with  its  rudimentary  spinous  pro- 
cess. 4.  The  intervertebral  notch.  5.  The  transverse  process.  6.  The  vertebral  fora- 
men. 7.  Superior  articular  surface.  8,  The  tubercle  for  the  attachment  of  the 
transverse  ligament. 

t  A  lateral  view  of  the  axis.  I.  The  body.  2.  The  odontoid  process.  3.  The 
smooth  facet  on  the  anterior  surface  of  the  odontoid  process  which  articulates  with  the 
anterior  arch  of  the  atlas.  4.  The  lamina.  5.  The  spinous  process.  6.  The  trans- 
verse process  pierced  obliquely  by  the  vertebral  foramen.  7.  The  superior  articular 
surface.     8.  The  inferior  articular  process. 

4 


26  DORSAL  VERTEBRiE. 

They  are  circular  and  nearly  horizontal,  having  a  slight  inclination 
outwards.  The  inferior  articulating  processes  look  downwards  and 
forwards,  as  do  the  same  processes  in  the  other  cervical  vertebra. 
The  lower  surface  of  the  body  is  convex,  and  is  received  into  the 
concavity  upon  the  upper  surface  of  the  third  vertebra. 

The    Vertebra   prominens,   or   seventh   cervical,  approaches   in 
character  to  the  upper  dorsal  vertebra. 
^^'   ■  It  has   received   its    designation   from 

having  a  very  long  spinous  process, 
which  is  single  and  terminated  by  a 
tubercle,  and  forms  a  considerable  pro- 
jection on  the  back  part  of  the  neck ; 
to  the  extremity  of  this  process  the 
ligamentum  aucha3  is  attached.  The 
transverse  processes  have  each  a  small 
foramen  for  the  transmission  of  the 
vertebral  vein. 

Dorsal  Vertebrcs. — The  bodi/  of  a  dor- 
sal vertebra  is  longer  from  before  back- 
wards than  from  side  to  side,  particularly  in  the  middle  of  the  dorsal 
region ;  it  is  thicker  behind  than  before,  and  marked  on  each  side 
by  two  half-articulating  surfaces  for  the  heads  of  two  ribs.  The 
pedicles  are  strong  and  the  lamince  broad;  the  foramen  round,  and 
the  inferior  intervertebral  notch  of  large  size.  The  spinous  process 
is  long,  almost  perpendicular  in  direction,  and  terminated  by  a 
tubercle.  The  transverse  processes  are  large  and  strong,  and  directed 
obliquely  backwards.  Upon  their  points  is  a  small  depression  for 
the  articulation  of  the  tubercle  of  a  rib.  The  articular  processes 
are  vertical,  the  superior  facing  directly  backwards,  and  the  inferior 
directly  forwards. 

The  peculiar  vertebrae  in  the  dorsal  region  are  the  first,  ninth, 
tenth,  eleventh,  and  twelfth.  The  j^?'s^  dorsal  vertebra  approaches 
very  closely  in  character  to  the  last  cervical.  The  body  is  broad 
from  side  to  side,  and  concave  above.  The  superior  articular 
processes  are  oblique,  and  the  spinous  process  horizontal.  It  has 
an  entire  articular  surface  for  the  first  rib,  and  a  half  surface  for 
the  second.  The  ninth  dorsal  vertebra  has  only  one  half  arti- 
cular surface  at  each  side.  The  tenth  has  a  single  entire  articular 
surface  at  each  side.  The  eleventh  and  twelfth  have  each  a  single 
entire  articular  surface  at  each  side  ;  they  approach  in  character  to 
the  lumbar  vertebra) ;  their  transverse  processes  are  very  short, 
and  have  no  articulation  with  the  corresponding  ribs.  The  trans- 
verse processes  of  the  twelfth  dorsal  vertebra  are  quite  rudi- 
mentary. 

*  A  lateral  view  of  a  dorsal  vertebra.  1.  Tlic  body.  2,  2.  Articular  facets  for  the 
heads  of  ribs.  3.  The  pedicle.  4.  The  superior  intervertebral  notch.  5.  The  inferior 
intervertel)ral  notcli.  {].  The  spinous  proccs.'s.  7.  The  extremity  of  the  transverse 
process  marked  by  an  articular  surface  for  the  tubercle  of  a  rib.  8.  The  two  superior 
articular  processes  looking  backwards.  9.  The  two  inferior  articular  processes  looking 
forwards. 


LUMBAR  VERTEBRA GENERAL  CONSIDERATIONS.         27 

Lumbar  VertehrcB. — These  are  the  largest  pieces  of  the  vertebral 
column.    The  body  is  broad  and  large,  v    c* 

and  thicker  before  than  behind.     The  ^^'   ' 

pedicles  very  strong ;  the  lamince  thick 
and  narrow;  the  inferior  interverte- 
bral notches  very  large,  and  the  fora- 
men large  and  oval.  The  spinous  pro- 
cess is  thick  and  broad.  The  trans- 
verse processes  slender,  pointed,  and 
directed  only  slightly  backwards.  The 
superior  articular  processes  are  con- 
cave, and  look  backwards  and  inwards ;  the  inferior,  convex,  and 
look  forwards  and  outwards.  The  last  lumbar  vertebra  differs 
from  the  rest  in  having  the  body  very  much  bevelled  posteriorly, 
so  as  to  be  broad  in  front  and  narrow  behind. 

General  Considerations. — Viewed  as  a  whole,  the  vertebral  column 
represents  two  pyramids  appUed  base  to  base,  the  superior  being 
formed  by  all  the  vertebrae  from  the  second  cervical  to  the  last 
lumbar,  and  the  inferior  by  the  sacrum  and  coccyx.  Examined 
more  attentively,  it  will  be  seen  to  be  composed  of  four  irregular 
pyramids,  applied  to  each  other  by  their  smaller  extremities  and  by 
their  bases.  The  smaller  extremity  of  the  uppermost  pyramid  is 
formed  by  the  axis,  or  second  cervical  vertebra ;  and  its  base,  by 
the  first  dorsal.  The  second  pyramid  is  inverted  ;  having  its  base 
at  the  first  dorsal,  and  the  smaller  end  at  the  fourth.  The  third 
pyramid  commences  at  the  fourth  dorsal,  and  gradually  enlarges 
to  the  fifth  lumbar.  The  fourth  pyramid  is  formed  by  the  sacrum 
and  coccyx. 

The  bodies  of  the  vertebras  are  broad  in  the  cervical  region,  nar- 
rowed almost  to  an  angle  in  the  middle  of  the  dorsal,  and  again 
broad  in  the  lumbar  region.  The  arches  are  broad  and  imbricated 
in  the  cervical  and  dorsal  regions,  the  inferior  border  of  each  over- 
lapping the  superior  of  the  next.  In  the  lumbar  region  they  are 
narrow,  and  leave  a  considerable  interval  between  them. 

The  spinous  processes  are  horizontal  in  the  cervical,  and  become 
gradually  oblique  in  the  upper  part  of  the  dorsal  region.  In  the 
middle  of  the  dorsal  region  they  are  nearly  vertical  and  imbricated, 
and  towards  its  lower  part  assume  the  direction  of  the  lumbar 
spines,  which  are  quite  horizontal.  The  transverse  processes  deve- 
loped in  their  most  rudimentary  form  in  the  axis,  gradually  increase 
in  length  to  the  first  dorsal  vertebra.  In  the  dorsal  region  they 
project  obliquely  backwards,  and  diminish  suddenly  in  length  in  the 
eleventh  and  twelfth  vertebrce,  where  they  are  very  small.  In  the 
lumbar  region  they  increase  to  the  middle  transverse  process,  and 
again  subside  in  length  to  the  last.  The  intervertebral  foramina 
formed  by  the  juxtaposition  of  the  notches,  are  smallest  in  the  cer- 

*  A  lateral  view  of  a  lumbar  vertebra.     1.  The  body.     9.  The  pedicle.  3.  The 

superior  intervertebral  notch.     4.  The  inferior  intervertebral  notch.     5.  The  spinous 

process.     6.  The  transverse  process.     7.  The  superior  articular  processes.  8.  The 
inferior  articular  processes. 


28  FALSE  VERTEBE.E. 

vical  region,  and  gradually  increase  to  the  last  lumbar.  On  either 
side  of  the  spinous  processes,  and  extending  the  whole  length  of  the 
column,  is  the  vertebral  groove,  which  is  shallow  in  the  cervical, 
and  deeper  in  the  dorsal  and  lumbar  regions.  It  lodges  the  prin- 
cipal muscles  of  the  back. 

Viewed  from  the  side,  the  vertebral  column  presents  several 
curves,  the  principal  of  which  is  situated  in  the  dorsal  region,  the 
concavity  looking  forwards.  In  the  cervical  and  lumbar  regions 
the  column  is  convex  in  front ;  and  in  the  pelvis  an  anterior  con- 
cave curve  is  formed  by  the  sacrum  and  coccyx.  Besides  the 
antero-posterior  curves  a  slight  lateral  curve  exists  in  the  dorsal 
region,  having  its  convexity  towards  the  right  side. 

Devehpement.  The  vertebras,  with  the  exception  of  the  atlas, 
axis,  and  vertebra  prominens,  are  developed  by  three  points  of 
ossification,  one  for  each  lamella,  and  one  for  the  body.  To  these 
are  afterwards  added  six  additional  centres ;  one  for  each  trans- 
verse process,  two  (sometimes  united  into  one)  for  the  spinous  pro- 
cess, and  one  for  the  upper  and  under  surface  of  the  body.  The 
atlas  has  five  centres ;  one  (sometimes  two)  for  the  anterior  arch, 
one  for  each  lateral  mass,  and  two  for  the  posterior  arch.  The 
axis  has  five  original  centres ;  one  (sometimes  two)  for  the  body, 
two  for  the  odontoid  process,  and  one  for  each  lamella.  The  ver- 
tebra prominens  has  likewise  five ;  one  for  the  body,  one  for  each 
anterior  segment  of  the  transverse  process,  and  one  for  each  lamella. 

The  ossification  of  the  arches  of  the  vertebras  commences  from 
above,  and  proceeds  gradually  downwards  ;  hence  arrest  of  de- 
velopement  gives  rise  to  spina  bifida,  generally  in  the  loins.  Ossi- 
fication of  the  bodies,  on  the  contrary,  commences  from  the  centre, 
and  proceeds  from  that  point  towards  the  extremities  of  the  column  ; 
hence  imperfection  of  the  bodies  occurs  either  in  the  upper  or  lower 
vertebrae. 

Mtlachment  of  muscles. — To  the  Mtlas  are  attached  ten  pairs  of 
muscles :  the  longus  colU,  rectus  anticus  minor,  rectus  lateralis, 
rectus  posticus  minor,  obliquus  superior  and  inferior,  splenius  colli, 
levator  anguli  scapulae,  first  interspinous,  and  first  intei'transverse. 

To  the  axis  are  attached  eleven  pairs,  viz  :  the  longus  coUi,  inter- 
transversales,  obliquus  inferior,  rectus  posticus  major,  interspinales, 
semi-spinalis  colli,  multifidis  spinse,  levator  anguli  scapulae,  splenius 
colli,  transversalis  colli,  and  scalenus  posticus. 

To  the  remaining  vertebra  generally,  thirty-two  pairs ;  viz.  pos- 
teriorhj,  the  trapezius,  latissimus  dorsi,  levator  anguli  scapulae,  rhom- 
boideus  minor  and  major,  serratus  posticus  superior  and  inferior, 
splenius,  sacro-lumbalis,  longissimus  dorsi,  spinalis  dorsi,  cervicalis 
ascendens,  transversalis  colli,  trachelo-mastoideus,  complexus,  semi- 
spinalis  dorsi  and  colli,  multifidus  spinse,  interspinales,  supraspinales, 
intertransversales,  levatores  costarum, — anteriorly,  the  rectus  anticus 
major,  longus  colli,  scalenus  anticus  and  posticus,  psoas  magnus, 
psoas  parvus,  quadratus  lumborum,  diaphragm,  obliquus  internus 
and  transversalis. 


SACRUM  AND  COCCYX.  29 

The  Sacrum  is  a  triangular  bone,  situated  at  the  lower  extremity 
of  the  vertebral  column,  and  formed  by  the  consolidation  of  five 
false  vertebrae.  It  is  divisible  into  an  anterior  and  posterior  surface, 
two  lateral  and  a  superior  border,  and  an  inferior  extremity. 

The  anterior  surface  is  concave,  and  marked  by  four  transverse 
lines,  which  indicate  its  original  constitution  of  five  separate  pieces. 
At  the  extremities  of  these  lines,  on  each  side,  are  the  four  anterior 
sacral  foramina,  which  diminish  in  size  from  above  downwards,  and 
transmit  the  anterior  sacral  nerves.  The  projection  of  the  superior 
piece  is  called  the  jiroinontory  of  the  sacrum. 

The  'posterior  surface  is  convex.  Upon  the  middle  line  is  a  rough 
crest  formed  by  the  rudiments  of  four  spinous  processes,  the  fifth 
remaining  undeveloped,  and  exposing  the  lower  termination  of  the 
sacral  canal.  The  rudiments  of  the  fifth  are  situated  one  on  each  side 
of  the  termination  of  the  sacral  canal ;  they  are  named  the  sacral 
cornua,  and  articulate  with  the  cornua  of  the  coccyx.  Parallel  with 
the  middle  line,  on  each  side,  are  the  openings  of  the  four  posterior 
sacral  formina ;  they  are  smaller  than  the  anterior,  and  transmit  the 
posterior  sacral  nerves.  Immediately  external  to  each  of  the  pos- 
terior sacral  foramina  is  a  tubercle,  representing  a  rudimentary 
transverse  process.  The  -first  transverse  tubercle  corresponds  with 
the  angle  of  the  superior  border  of  the  bone ;  the  second  is  small, 
and  enters  into  the  formation  of  the  sacro-iliac  articulation ;  the 
third  is  large,  and  gives  attachment  to 
the  oblique  sacro-iliac  ligament ;  the 
fourlk  and  jiflh  are  smaller  and  serve  for 
the  attachment  of  the  sacro-ischiatic 
ligaments.  The  lateral  border  presents 
superiorly  a  broad  and  ear-shaped  sur- 
face to  articulate  with  the  ilium ;  and 
inferiorly  a  sharp  edge,  to  which  the 
greater  and  lesser  sacro-ischiatic  liga- 
ments are  attached.  On  the  superior 
border,  in  the  middle  line,  is  an  oval 
articular  surface,  which  corresponds 
with  the  under  part  of  the  body  of  the 
last  lumbar  vertebra ;  and  on  each  side,  a 
broad  triangular  surface  which  supports 

the  lumbo-sacral  nerve  and  psoas  magnus  muscle.  Immediately 
behind  the  vertebral  articular  surface  is  the  triangular  entrance  of 
the  sacral  canal ;  and  on  each  side  of  this  opening  an  articular 
process,  which  looks  backwards  and  inwards,  like  the  superior  ar- 
ticular processes  of  the  lumbar  vertebrae.   In  front  of  each  articular 

*  The  sacrum  seen  upon  its  anterior  surface.  1,  1.  The  transverse  lines  markinof 
the  original  constitution  of  the  bone  of  four  pieces.  2, 2.  The  anterior  sacral  foramina.  3. 
The  promontory  of  the  sacrum.  4.  Tlie  ear  shaped  surface  which  articulates  witli  tlie 
ilium.  5.  The  sharp  edge  to  wliich  the  sacro-ischiatic  ligaments  are  attached.  6  The 
vertebral  articular  surface.  7.  The  broad  triangular  surface  which  supports  the  psoas 
muscle  and  lumbo-sacral  nerve.  8.  The  articular  process  of  the  right  side.  9.  The 
inferior  extremity,  or  apex  of  the  sacrum.  10.  One  of  the  sacral  cornua.  11.  The 
notch  which  is  converted  into  a  foramen  by  the  coccyx. 


30 


BONES  OF  THE  CEANIU3I. 


process  is  an  intervertebral  notch.  The  inferior  extremity  presents 
a  small  oval  surface  which  articulates  with  the  coccyx ;  and  on 
each  side  a  notch,  which  with  a  corresponding  notch  in  the  upper 
border  of.  the  coccyx  forms  the  foramen  for  the  transmission  of  the 
fifth  sacral  nerve. 

Developement. — By  twenty-one  points  of  ossification  ;  five  for  each 
of  the  three  first  pieces,  viz. — one  for  the  body,  one  for  each  lateral 
portion,  and  one  for  each  lamina ;  and  three  for  each  of  the  two 
last,  viz. — one  for  the  body,  and  one  for  each  lateral  portion. 

Articulations. — With,  four  bones  ;  the  last  lumbar  vertebra,  ossa 
innominata  and  coccyx, 

Attachment  of  Muscles. — To  seven  pairs  ;  in  front  the  pyriformis, 
on  the  side  the  coccygeus,  and  behind  the  gluteus  maximus,  latissi- 
mus  dorsi,  longissimus  dorsi,  sacro-lumbalis,  and  multifidus  spinse. 

The  Coccyx  (xoxxug  cuckoo,  from  resembling  a  cuckoo's  beak)  is 
composed  of  four  small  pieces,  which  form  the  caudal  termina- 
tion of  the  vertebral  column.  The  superior  piece  is  broad,  and  ex- 
pands laterally  into  two  transverse  processes :  it  is  surmounted  by 
an  oval  articular  surface  and  two  cornua  ;  the  former  to  articulate 
with  the  apex  of  the  sacrum,  and  the  latter  with  the  sacral  cornua. 
The  three  latter  pieces  diminish  in  size  from  above  downwards,  and 
are  frequently  consolidated  into  a  single  bone. 

Developement. — By  four  centres,  one  for  each  piece. 

Articulations. — With  the  sacrum. 

Attachment  of  Muscles. — To  three  pairs,  and  one  single  muscle  : 
gluteus  maximus,  coccygeus,  posterior  fibres  of  the  levator  ani  and 
sphincter  ani. 


OF  THE  SKULL. 


Fig.  8/ 


--^y 


The  skull,  or  superior  expan- 
sion of  the  vertebral  column,  is 
divisible  into  two  parts, — the 
cranium  and  the  face  ;  the  former 
being  adapted  by  its  form,  struc- 
ture, and  strength  to  contain  and 
protect  the  brain,  and  the  latter 
the  chief  organs  of  sense. 

The  Cranium  is  composed  of 
eight  separate  bones ;  viz.  the  oc- 
cipital, two  parietal,  frontal,  two 
temporal,  splicnoidal,  ethmoidal. 

OccrpiTAL  Bone. — This  bone  is 
situated  at  the  posterior  part  and 
base  of  tl  ic  cranium.  It  is  trapezoid 
in  form,  and  divisible  into  two  sur- 
faces, four  borders,  and  four  angles. 


*  The  external  surface  of  the  occipital  bone.     l.The  superior  semicircular  ridge. 
2.  The  occipital  protuberance.     3.  The  spine.     4.  The  inferior  semicircular  ridge.     5. 


OCCIPITAL  BONE.  31 

External  Surface. — Crossing  the  middle  of  the  bone  transversely, 
from  one  lateral  angle  to  the  other,  is  a  prominent  ridge,  the  superior 
semicircular  ridge.  In  the  middle  of  the  ridge  is  a  projection,  called 
the  occipital  protuberance ;  and  descending  from  it  a  small  vertical 
ridge,  the  spine.  Above  and  below  the  superior  semicircular  ridge  the 
surface  is  rough,  for  the  attachment  of  muscles.  About  three-quarters 
of  an  inch  below  this  line  is  another  transverse  ridge,  the  inferior 
seinicircular  ridge,  and  beneath  the  latter,  the  foramen  magnum. 
On  each  side  of  the  foramen  magnum,  nearer  to  its  anterior  than  its 
posterior  segment,  and  encroaching  somewhat  upon  the  opening,  is 
an  oblong  articular  surface — the  condyle,  for  articulation  with  the 
atlas.  The  condyles  approach  towards  each  other  anteriorly,  and 
their  articular  surfaces  look  downwards  and  outwards.  Directly 
behind  each  condyle  is  an  irregular  fossa,  and  a  small  opening,  the 
posterior  condyloid  foramen  for  the  transmission  of  a  vein  to  the 
lateral  sinus.  In  front  of  the  condyle  is  the  anterior  condyloid  for  amen, 
for  the  hyjDOglossal  nerve  ;  and  on  each  side  of  each  condyle  a  pro- 
jecting ridge,  the  transverse  process,  excavated  in  front  by  a  notch 
which  forms  part  of  the  jugular  foramen.  In  front  of  the  foramen 
magnum  is  a  thick  square  mass,  the  basilar  process,  and  in  the  centre 
of  the  basilar  process  a  small  tubercle  for  the  attachment  of  the 
superior  and  middle  constrictor  muscles  of  the  pharynx. 

Internal  Surface. — Upon  the  internal  surface  is  a  crucial  ridge, 
which  divides  the  bone  into  four  fossas  ;  the  two  superior  or  cerebral 
fossae  lodging  the  posterior  lobes  of  the  cerebrum  ;  and  the  two  in- 
ferior or  cerebellar,  the  lateral  lobes  of  the  cerebellum.  The  superior 
arm  of  the  crucial  ridge  is  grooved  for  the  superior  longitudinal 
sinus,  and  gives  attachment  to  the  falx  cerebri ;  the  inferior  arm  is 
sharp  and  prominent,  for  the  attachment  of  the  falx  cerebelli,  and 
slightly  grooved,  for  the  two  occipital  sinuses.  The  transverse 
ridge  gives  attachment  to  the  tentorium  cerebeUi,  and  is  deeply 
grooved,  for  the  lateral  sinuses.  At  the  point  of  meeting  of  the  four 
arms,  is  a  projection,  the  internal  occipital  protuberance,  which  cor- 
responds with  the  similar  process  situated  upon  the  external  surface 
of  the  bone.  The  convergence  of  the  four  grooves  forms  a  slightly 
depressed  fossa,  upon  which  rests  the  torcular  Herophih.  In  the 
centre  of  the  basilar  portion  of  the  bone  is  the  foramen  magnum, 
oblong  in  form  and  larger  behind  than  before,  transmitting  the  spinal 
cord,  spinal  accessory  nerves,  and  vertebral  arteries.  Upon  the 
lateral  margins  of  the  foramen  magnum  are  two  rough  eminences, 
which  give  attachment  to  the  odontoid  ligaments,  and  immediately 
above  these  the  openings  of  the  anterior  condyloid  foramina.     In 

The  foramen  magnum.  6.  The  condyle  of  the  right  side.  7.  The  posterior  con- 
dyloid fossa,  in  which  the  posterior  condyloid  foramen  is  found.  8.  The  anterior  con- 
dyloid foramen  concealed  by  the  margin  of  the  condyle.  9.  The  transverse  process  ;  this 
process  upon  the  internal  surface  of  the  bone  forms  the  jugular  eminence.  10.  The 
notch  in  front  of  the  jugular  eminence  which  forms  part  of  the  jugular  foramen.  11. 
The  basilar  process.  12,  12.  The  rougli  projections  into  wliich  the  odontoid  ligaments 
are  inserted. 


32 


OCCIPITAL  BONE. 


Tier.  9.* 


front  of  the  foramen  magnum 
is  the  basilar  process,  grooved 
on  its  surface,  for  supporting  the 
medulla  oblongata ;  and  on  each 
'side  of  the  foramen  a  groove, 
for  the  termination  of  the  lateral 
sinus ;  a  smooth  surface  which 
forms  part  of  the  jugular  fossa  ; 
and  a  projecting  process  which 
divides  the  two  and  is  called  the 
jugular  eminence.  Into  the  jugu- 
lar fossa  will  be  seen  opening 
the  posterior  condyloid  foramen. 
The  superior  borders  are 
very  much  serrated  and  assist 
in  forming  the  lambdoidal 
suture;  the  inferior  are  rough, 
but  not  serrated,  and  articu- 
late with  the  mastoid  portion 
of  the  temporal  bone  by  means 
of  the  additamentum  suturse  lambdoidalis.  The  jugular  eminence 
and  the  side  of  the  basilar  process  articulate  with  the  petrous  por- 
tion of  the  temporal  bone,  and  the  intermediate  space,  which  is 
irregularly  notched,  forms  the  posterior  boundary  of  the  jugular 
foramen,  or  foramen  lacerum  posterius. 

The  angles  of  the  occipital  bone,  are  the  superior,  inferior,  and 
two  lateral.  The  superior  angle  is  received  into  the  interval  formed 
by  the  union  of  the  posterior  and  superior  angles  of  the  parietal 
bones,  and  corresponds  with  that  portion  of  the  foetal  head  which  is 
called  the  posterior  fontanelle.  The  inferior  angle  is  the  articular 
extremity  of  the  basilar  process.  The  lateral  angles  at  each  side 
project  into  that  interval  formed  by  the  articulation  of  the  posterior 
and  inferior  angle  of  the  parietal  with  the  mastoid  portion  of  the 
temporal  bone. 

Developement. — By  four  centres ;  one  (sometimes  two)  for  the 
posterior  portion,  one  for  each  condyle,  and  one  for  the  basilar  pro- 
cess. 

Articulations. — With  six  bones;  two  parietal,  two  temporal,  sphe- 
noid, and  atlas. 

Attachment  of  Muscles. — To  thirteen  pairs ;  to  the  rough  surface 


*  Tlic  internal  KUifacc  of  the  occipital  bone.  1.  The  left  cerebral  fosaa.  2.  The 
left  cerebellar  fossa.  3.  The  g-roove  for  the  posterior  part  of  the  superior  longitudinal 
sinus.  4.  The  spine  for  the  falx  cerebelli,  and  groove  for  the  occipital  sinus.  5.  The 
groove  for  the  left  Intcral  sinus.  6.  The  internal  occipital  protuberance  wliich  lodges 
the  torciilar  Herophili.  7.  The  foramen  magnum.  8.  'J'he  basilar  process,  grooved  for 
the  medulhi  oblongata.  9.  The  termination  of  the  groove  for  tlie  lateral  sinus,  bounded 
externally  by  the  jugnlar  crninonco.  10.  Tlie  jugidar  fossa  ;  this  fossa  is  completed  by 
the  petrous  portion  of  the  temporal  bone.  11.  Tlie  superior  border  of  the  bone.  12. 
The  inferior  border.  13.  The  border  which  articulates  with  the  petrous  portion  of  the 
temporal  bone.     14.  The  anterior  condyloid  foramen. 


PARIETAL  BONE. 


33 


above  the  superior  semicircular  ridge,  the  occipito-frontaHs  ;  to  the 
superior  semicircular  ridge,  the  trapezius  and  sterno-mastoid ;  to  the 
rough  space  between  the  ridges,  complexus  and  splenius  capitis  ;  to 
the  space  between  the  inferior  semicircular  ridge  and  the  foramen 
magnum,  the  rectus  posticus  major  and  minor,  and  obliquus  supe- 
rior ;  to  the  transverse  process,  the  rectus  lateralis ;  and  to  the 
basilar  process,  the  rectus  anticus  major  and  minor,  and  superior 

and  middle  constrictor  muscles. 

Fig.  10.* 


;l;«f|iP%J>^f 


Parietal  Bone. — The  pa- 
rietal bone  is  situated  at  the 
side  and  vertex  of  the  skull ;  it 
is  quadrilateral  in  form,  and  di- 
visible into  an  external  and  in- 
ternal surface,  four  borders  and 
four  angles.  The  superior  border 
is  straight,  to  articulate  wdth  its 
fellow  of  the  opposite  side.  The 
inferior  border  is  arched  and 
thin,  to  articulate  with  the  tem- 
poral bone.  The  anterior  border 
is  concave,  and  the  posterior 
somewhat  convex. 

External  Surface. — Crossing  the  bone  in  a  longitudinal  direction 
from  the  anterior  to  the  posterior  border,  is  an  arched  hne,  the 
temporal  ridge,  to  which  the  temporal  fascia  is  attached.  In  the 
middle  of  this  line,  and  nearly  in  the  centre  of  the  bone,  is  the  pro- 
jection called  the  -parieial  boss 
or  eminence,  which  marks  the 
centre  of  ossification.  Above 
the  temporal  ridge  the  surface 
is  rough,  and  covered  by  the 
aponeurosis  of  the  occipito- 
frontahs ;  below  the  ridge  the 
bone  is  smooth  for  the  attach- 
ment of  the  fleshy  fibres  of  the 
temporal  muscle.  Near  the 
superior  border  of  the  bone, 
and  at  about  one-third  from  its 
posterior  extremity,  is  the  pa- 
rietal foramen,  which  transmits 
a  vein  to  the  superior  longitu- 
dinal sinus. 

Internal  Surface. — The  internal  table  is  smooth,  and  marked 


Fig.  ll.t 


6' 


r-^-mmk:^... 


*  The  external  surface  of  the  left  parietal  bone.  1.  The  superior  or  sagittal  border. 
2.  The  inferior  or  squamous  border.  3.  The  anterior  or  coronal  border.  4.  The  pos- 
terior or  lambdoidal  border.  5.  The  temporal  ridge;  the  figure  is  situated  immediately 
in  front  of  the  parietal  eminence.  6.  The  parietal  foramen,  unusually  large  in  tiic 
bone  from  which  this  figure  was  drawn.  7.  The  anterior  inferior  or  elongated  angle. 
8.  The  posterior  inferior  or  truncated  angle. 

t  The  internal  surface  of  the  left  parietal  bone.    1.  The  superior,  or  sagittal  border. 

5 


34  PARIETAL  BONE. 

over  every  part  of  its  surface  by  numerous  furrows,  which  cor- 
respond with  the  ramifications  of  the  arteria  meningea  magna. 
Along  the  upper  border  is  part  of  a  shallow  groove,  completed  by 
the  opposite  parietal  bone,  which  serves  to  contain  the  superior 
longitudinal  sinus.  Some  slight  pits  are  also  observable  near  to  this 
groove,  wliich  lodge  the  glandulse  Pacchioni. 

The  anterior  inferior  angle  is  thin  and  lengthened,  and  articu- 
lates with  the  greater  wing  of  the  sphenoid  bone.  Upon  its 
inner  surface  it  is  deeply  channelled  by  a  groove  for  the  trunk  of 
the  arteria  meningea  magna.  This  groove  is  frequently  converted 
into  a  canal.  The  'posterior  inferior  angle  is  thick,  and  presents  a 
broad  and  shallow  groove  for  the  lateral  sinus. 

Developement. — By  a  single  centre. 

Articulations. — With_^ ye  bones;  with  the  opposite  parietal  bone, 
the  occipital,  frontal,  temporal,  and  sphenoid. 

Attachment  of  Muscles. — To  one  only, — the  temporal.  The  occi- 
pito-frontalis  glides  over  its  upper  surface. 

Frontal  Bone. — The  frontal  bone  bears  some  resemblance  in 
form  to  the  under  valve  of  a  scallop  shell.  It  is  situated  at  the 
anterior  part  of  the  cranium,  forming  the  forehead,  and  assists  in 
the  construction  of  the  roof  of  the  orbits  and  nose.  Hence  it  is 
divisible  into  a  superior  or  frontal  portion,  and  an  inferior  or  orbito- 
nasal portion.  Each  of  these  portions  presents  for  examination  an 
external  and  internal  surface,  borders  and  processes. 

External  Surface. — At  about  the  middle  of  each  lateral  half  of  the 
frontal  portion  is  a  projection,  the  frontal  boss  or  eminence,  which 
denotes  the  situation  of  the  centre  of  ossification.  Below  these 
points  are  the  superciliary  ridges,  large  towards  their  inner  termina- 
tion, and  becoming  gradually  smaller  as  they  arch  outwards  ;  they 
support  the  eyebrows.  Beneath  the  superciliary  ridges  are  the 
sharp  and  prominent  arches  which  form  the  upper  margin  of  the 
orbits,  the  supra-orbital  ridges.  Externally  the  supra-orbital  ridge 
terminates  in  the  external  angular  process,  and  internally  in  the 
internal  angular  process  ;  at  the  inner  third  of  this  ridge  is  a  notch, 
sometimes  converted  into  a  foramen,  the  supra-orbital  notch,  which 
gives  passage  to  the  supra-orbital  or  frontal  artery,  veins,  and 
nerve.  Between  the  two  superciliary  ridges  is  a  rough  projection, 
the  nasal  tuberosity :  the  whole  of  this  portion  of  the  bone  is  some- 
what prominent,  and  denotes  the  situation  of  the  frontal  sinuses. 
Extending  upwards  and  backwards  from  the  external  angular  pro- 
cess is  a  sharp  ridge,  the  commencement  of  the  temporal  ridge,  and 
beneath  this  a  depressed  surface  that  forms  part  of  the  temporal 
fossa. 

2.  The  inferior,  or  squamous  border.  3.  Tlic  anterior,  or  coronal  border.  4.  The 
posterior,  or  lambdoidal  border.  5.  Part  of  the  jrroovc  for  the  superior  longitudinal 
Hinus.  G.  The  internal  termination  of  the  parietal  foramen.  7.  The  anterior  inferior 
angle  of  the  bone,  on  wliicli  is  seen  the  groove  for  the  trunk  of  the  arteria  meningea 
magna.  8.  The  posterior  inferior  angle,  upon  which  is  seen  a  portion  of  the  groove 
for  the  lateral  sinus. 


FRONTAL  BONE. 


35 


"''■M.irjp^ 


The  orhito-nasal  portion  of  the  bone  consists  of  two  thin  processes, 
the  orbital  plates,  which  form  the  roof  of  the  orbits,  and  of  an  inter- 
vening notch  which  lodges  the  ethmoid  bone,  and  is  called  the 
ethmoidal  fissure.  The  edges  of  the  ethmoidal  fissure  are  hollowed 
into  cavities,  which,  by  their 
union  with   the  ethmoid   bone,  Fiff- 12.* 

complete  the  ethmoidal  cells ; 
and,  crossing  these  edges  trans- 
versely, are  two  small  grooves, 
sometimes  canals,  which  open 
into  the  orbit  by  the  anterior 
and  posterior  ethmoidal  fora- 
mina. At  the  anterior  termi- 
nation of  these  edges,  are  the 
irregular  openings  which  lead 
into  the  frontal  sinuses  ;  and  be- 
tween the  two  internal  angular 
processes  is  a  rough  excavation 
which  receives  the  nasal  bones, 
and  a  projecting  process,  the 
nasal  spine.     Upon  each  orbital  } 

plate,  immediately  beneath  the 

external  angular  process,  is  a  shallow  depression  which  lodges  the 
lachrymal  gland ;  and  beneath  the  internal  angular  process  a  small 
pit,  sometimes  a  tubercle,  to  which  the  cartilaginous  pulley  of  the 
superior  oblique  muscle  is  attached. 

Internal  Surface. — Along  the  middle  hne  of  this  surface  is  a 
grooved  ridge,  the  edges  of  the  ridge  giving  attachment  to  the  falx 
cerebri  and  the  groove  lodging  the  superior  longitudinal  sinus.  At 
the  commencement  of  the  ridge  is  an  opening,  sometimes  completed 
by  the  ethmoid  bone,  the.  foramen  ccecum.  This  opening  lodges  a 
process  of  the  dura  mater,  and  occasionally  gives  passage  to  a 
small  vein  which  communicates  with  the  nasal  veins.  On  each  side 
of  the  vertical  ridge  are  some  slight  depressions  which  lodge  the 
glandulae  Pacchioni,  and  on  the  orbital  plates  a  number  of  irre- 
gular pits  called  digital  fossa,  which  correspond  with  the  convolu- 
tions of  the  anterior  lobes  of  the  cerebrum.  The  superior  border  is 
thick  and  strongly  serrated,  bevelled  at  the  expense  of  the  internal 
table  in  the  middle,  where  it  rests  upon  the  junction  of  the  two 
parietal,  and  at  the  expense  of  the  external  table,  on  each  side, 
where  it  receives  the  lateral  pressure  of  those  bones.     The  infe- 


*The  external  surface  of  the  frontal  bone.  1.  The  situation  of  the  frontal  emi- 
nence of  the  right  side.  2,  The  superciliary  ridge.  3.  The  supra-orbital  ridge.  4. 
Tlie  external  angular  process.  5.  The  internal  angular  process.  6.  The  supra-orbital 
notch  for  the  transmission  of  the  supra-orbital  nerve,  and  artery  ;  in  the  figure  it  is 
almost  converted  into  a  foramen  by  a  small  spiculum  of  bone.  7.  The  nasal  tubero- 
sity ;  tlie  swelling  around  this  point  denotes  llie  situation  of  the  frontal  sinuses.  8. 
The  temporal  ridge  commencing  from  the  external  angular  process  (4).  The  depres- 
sion in  which  tlie  figure  8  is  situated  is  a  part  of  the  temporal  fcssa.   9.  The  nasal  spine. 


36 


TEMPORAL  BONE. 


visible 

The 

thin,  tr 


Fig.  14.t 


rior  border  is  thin,  irregular, 
and  squamous,  and  articulates 
with  the  sphenoid  bone. 

Developement. — By  two  cen- 
tres, one  for  each  lateral  half. 
Articulations. — With  tiuelve 
bones ;  the  two  parietal,  the 
sphenoid,  ethmoid,  two  nasal, 
two  superior  maxillary,  two 
lachrymal,  and  two  malar. 

Jlttachment  of  Muscles. — To 
four  pairs ;  occipito-frontalis, 
orbicularis  palpebrarum,  cor- 
rugator  supercilii,  and  tem- 
poral. 

Temporal  Bone. — The  tem- 
poral bone  is  situated  at  the  side 
and  base  of  the  skull,  and  is  di- 
into  a  squamous,  mastoid,  and  petrous  portion. 
Squamous  portion,  forming  the  anterior  part  of  the  bone,  is 
anslucent,  and  contains  no  diploe.  Upon  its  external  surface 

it  is  smooth,  to  give  attachment 
to  the  fleshy  fibres  of  the  tem- 
poral muscle,  and  has  projecting 
from  it  an  arched  and  lengthened 
process,  the  zygoma.  Near  the 
commencement  of  the  zygoma 
upon  its  lower  border,  is  a  pro- 
jection called  the  tubercle,  to 
which  is  attached  the  external 
lateral  ligament  of  the  lower 
jaw,  and  continued  horizontally 
inwards  from  the  tubercle  a 
rounded  eminence,  the  eminentia 
articularis.  The  process  of  bone 
which  is  continued  from  the  tu- 
bercle of   the  zygoma    into  the 

*  Tho  internal  surface  of  the  frontal  bone  ;  the  bono  is  raised  in  such  a  manner  as  to 
show  the  orbito-nasal  portion.  1.  The  grooved  ridge  for  the  lodgment  of  ihe  superior 
longitudinal  sinus  and  attachment  of  the  falx.  2.  The  foramen  caacum.  3.  The  su- 
perior or  coronal  border  of  the  bono  ;  the  figure  is  situated  near  that  part  which  is 
bevelled  at  the  expense  of  the  internal  table.  4.  The  inferior  border  of  the  bone.  5. 
The  orbital  plate  of  the  left  side.  6.  Tlie  cellular  border  of  the  ethmoidal  fissure.  Tlie 
foramen  CiocMim  (2)  is  seen  tlirough  the  ethmoidal  fissure.  7.  The  anterior  and  pos- 
tcrior  ethmoidal  foramina;  the  anterior  seen  leading  into  its  canal.  8,  The  nasal  spine. 
9.  The  depression  within  the  external  angular  i)rocess  (12)  for  the  lachrymal  gland.  10. 
The  depression  for  the  pulley  of  the  superior  oblique  muscle  of  the  eye  ;  immediately 
to  the  loft  of  this  number  is  the  supra-orbital  notch,  and  to  its  right  the  internal  angular 
process.  11.  The  opening  leading  into  the  frontal  sinuses.  The  same  parts  are  seen 
upon  the  opposite  side  of  the  figure.     12.  The  external  angular  process. 

t  The  external  surface  of  the  temporal  bone  of  the  left  side.     1.  The  squamous  por- 


TEMPORAL  BONE.  37 

eminentia  articularis  is  the  inferior  root  of  the  zygoma.  The  swpe- 
rior  root  is  continued,  upwards  from  the  upper  border  of  the  zygoma, 
and  forms  the  posterior  part  of  the  temporal  ridge,  serving  by  its 
projection  to  mark  the  division  of  the  squamous  from  the  mastoid 
portion  of  the  bone;  and  the  middle  root  is  continued  directly 
backwards,  and  terminates  abruptly  at  a  narrow  fissure— the 
fissura  Glaseri  or  glenoid  fissure.  The  internal  surface  of  the  squa- 
mous portion  is  marked  by  several  shallow  fossae,  which  correspond 
with  the  convolutions  of  the  cerebrum,  and  by  a  furrow  for  the  pos- 
terior branch  of  the  arteria  meningea  magna.  The  superior  or 
squamous  border,  is  very  thin  and  bevelled  at  the  expense  of  the 
inner  surface,  so  as  to  overlap  the  lower  and  arched  border  of  the 
parietal  bone.  The  inferior  border  is  thick  and  dentated  to  articu- 
late with  the  spinous  process  of  the  sphenoid  bone. 

The  Mastoid  'portion  forms  the  posterior  part  of  the  bone  ;  it  is 
thick  and  hollowed  between  its  tables  into  a  loose  and  cellular  diploe. 
Upon  its  external  surf  ace  it  is  rough  for  the  attachment  of  muscles, 
and  contrasts  strongly  with  the  smooth  and  poHshed-hke  surface  of 
the  squamous  portion ;  every  part  of  this  surface  is  pierced  by 
small  foramina,  which  give  passage  to  minute  arteries  and  veins  ; 
one  of  these  openings,  obHque  in  its  direction,  of  large  size,  and 
situated  near  the  posterior  border  of  the  bone,  the  mastoid  foramen, 
transmits  a  vein  to  the  lateral  sinus.  This  foramen  is  not  unfre- 
quently  situated  in  the  occipital  bone.  The  inferior  part  of  this  por- 
tion is  round  and  expanded, — the  m.astoid  process, — and  excavated  in 
its  interior  into  numerous  cells,  w^iich  form  a  part  of  the  organ  of 
hearing.  In  front  of  the  mastoid  process  and  between  the  supe- 
rior and  middle  roots  of  the  zygoma,  is  the  large  oval  opening  of  the 
meatus  auditorius  externus,  surrounded  by  a  rough  lip,  the  processus 
auditorius.  Directly  to  the  inner  side,  and  partly  concealed  by  the 
mastoid  process,  is  a  deep  groove,  the  digastric  fossa  ;  and  a  little 
more  internally  the  occipital  groove,  which  lodges  the  occipital 
artery.  Upon  its  internal  surface  the  mastoid  portion  presents  a 
broad  and  shallow  groove  for  the  lateral  sinus,  and  terminating  in 
this  groove  the  internal  opening  of  the  mastoid  foramen.  The 
superior  border  of  the  mastoid  portion  is  dentated,  and  its  posterior 
border  thick  and  less  serrated  for  articulation  with  the  inferior  border 
of  the  occipital  bone. 

The  Petrous  portion  of  the  temporal  bone  is  named  from  its  ex- 
treme hardness  and  density.  It  is  a  three-sided  pyramid,  projecting 
horizontally  forwards  into  the  base  of  the  skull,  the  base  being 

tion.  2.  The  mastoid  portion.  3.  The  extremity  of  the  petrous  portion.  4.  The 
zygoma.  5.  Indicates  the  tubercle  of  the  zygoma,  and  at  the  same  time  its  anterior 
root  turning  inwards  to  form  the  eminentia  articularis.  6.  The  superior  root  of  the 
zygoma,  forming  the  posterior  part  of  the  temporal  ridge.  7.  The  middle  root  of  the 
zygoma  terminating  abruptly  at  the  glenoid  fissure.  8.  The  mastoid  foramen.  9.  The 
meatus  auditorius  externus,  surrounded  by  the  processus  auditorius.  10.  The  digastric 
fossa,  situated  immediately  to  the  inner  side  of  (2)  the  mastoid  process.  11.  The  sty- 
loid process.  12.  The  vaginal  process.  13.  The  glenoid  or  Glnserian  fissure;  the 
leading  line  from  this  number  crosses  the  rough  posterior  portion  of  the  glenoid  fossa. 
14.  The  opening  and  part  of  the  groove  for  tlic  Eustachian  tube. 


38  TEMPORAL  BONE,  ' 

applied  against  the  internal  surface  of  the  squamous  and  mastoid 
portions,  and  the  apex  being  received  into  the  triangular  interval  be- 
tween the  spinous  process  of  the  sphenoid  and  basilar  process  of  the 
occipital  bone.  For  convenience  of  description  it  is  divisible  into 
three  surfaces — anterior,  posterior,  and  basilar ;  and  three  borders 
— superior,  anterior,  and  posterior. 

Surfaces. — The  anterior  surface,  forming  the  posterior  boundary 

of  the  middle  fossa  of  the  interior 
rig.  15,*  of  the  base  of  the  skull,  presents 

^^^•^^f^  for  examination  from  base  to  apex, 

first  an  eminence  caused  by  the 
projection  of  the  perpendicular  se- 
micircular canal ;  next,  a  groove 
leading  to  an  irregular  oblique 
opening — the  hiatus  Fallopii — for 
the  transmission  of  the  petrosal 
branch  of  the  Vidian  nerve ; 
thirdly,  another  and  smaller  ob- 
lique foramen,  immediately  be- 
neath the  preceding,  for  the  pas- 
sage of  the  nervus  petrosus  su- 
perficialis  minor, — a  branch  of 
Jacobson's  nerve  ;  and  lastly  a  large  foramen  near  the  apex  of  the 
bone,  the  termination  of  the  carotid  canal. 

The  posterior  surface  forms  the  front  boundary  of  the  posterior 
fossa  of  the  base  of  the  skull ;  near  its  middle  is  the  oblique  entrance 
of  the  meatus  auditorius  internus.  The  meatus  pursues  a  course 
directly  outw^ards ;  it  is  about  one-third  of  an  inch  in  length,  and 
terminates  in  two  deep  depressions  (nearly  one-eighth  of  an  inch  in 
depth)  separated  by  a  sharp,  horizontal  ridge.  The  superior  depres- 
sion, the  smaller  of  the  two,  is  divided  at  its  extremity,  by  a  vertical 
ridge,  into  an  anterior  portion,  which  is  the  commencement  of  the 
aqua^ductus  Fallopii,  for  the  transmission  of  the  facial  nerve  ;  and 
a  posterior  portion  which  corresponds  with  the  upper  part  of  the 
inner  wall  of  the  vestibule,  and  is  pierced  by  numerous  openings  for 

*  The  left  temporal  bone,  seen  from  within.  1.  Tlie  squamous  portion.  2.  The 
mastoid  portion.  The  number  is  placed  immediately  above  the  inner  opening-  of  the 
mastoid  foramen.  3.  The  petrous  portion.  4.  Tiie  groove  for  the  posterior  branch 
of  the  arteria  meningca  magna.  5.  Tiie  bevelled  edge  of  tlie  squamous  border  of  the 
bone.  6.  The  zygoma.  7.  The  digastric  fossa  immediately  internal  to  the  mastoid 
process.  8.  The  occipital  groove.  !).  The  groove  for  the  lateral  sinus.  10.  Tlie  ele- 
vation upon  the  anterior  surficc  of  the  petrous  bone  marking  the  situation  of  the  per- 
pendicular semicircular  cunal.  11.  The  opening  of  termination  of  the  carotid  canal. 
12.  The  meatus  auditorius  internus.  13.  A  dotted  line  leads  upwards  from  tins  number  to 
the  narrow  fissure  which  lodges  a  process  of  the  dura  mater.  Another  line  leads  down- 
wards to  tlic  sharp  edge  which  conceals  the  opening  of  the  aquwductus  coclileaj,  while 
the  number  itself  is  situated  on  the  bony  lamina  whieli  overlies  the  opening  of  the 
aqutcductus  vcstibuli.  14.  'J'he  styloid  process,  l.'j.  The  sty lo-mnstoid  foramen.  16, 
The  carotid  foramen.  17.  The  jugular  process.  The  deep  excavation  to  the  left  of  this 
process  forms  part  of  the  jugular  fossa,  and  that  to  the  right  is  the  groove  for  the  vein 
of  the  cochlea.  18,  The  notch  for  tlie  fifth  nerve  upon  the  upper  border  of  the  petrous 
bone,  near  to  its  apex.  19.  The  extremity  of  the  petrous  bone  wliich  gives  origin  to 
the  levator  palati  and  tensor  lympani  muscles. 


TEMPORAL  BONE.  39 

the  passage  of  filaments  of  the  vestibular  nerve.  The  inferior 
depression  terminates  in  tv^o  oval  pits,  w^hich  correspond  with  the 
inferior  part  of  the  inner  wall  of  the  vestibule,  and  are  also  pierced 
with  openings  for  the  passage  of  filaments  of  the  vestibular  nerve. 
Upon  the  anterior  wall  of  the  infeiior  depression,  and  near  to  its 
termination,  is  a  spiral  groove,  perforated  by  minute  openings  for 
the  passage  of  the  filaments  of  the  cochlear  nerve;  and  in  the 
centre  of  the  spine  is  a  foramen  larger  than  the  rest,  which  leads 
into  the  central  canal  of  the  modiolus,  tuhulus  centralis  modioli. 
This  groove  corresponds  with  the  base  of  the  cochlea,  and  is 
termed  the  tractus  spiralis  foraminulenius.  Upon  the  posterior  wall 
of  the  depression,  and  opposite  to  the  spiral  groove,  is  a  longitudinal 
groove  leading  to  a  foramen  which  transmits  a  considerable  branch 
of  the  vestibular  nerve.  Above  the  meatus  auditorius  internus  is  a 
small  oblique  fissure,  and  a  minute  foramen ;  the  former  lodges  a 
process  of  the  dura  mater,  and  the  foramen  gives  passage  to  a 
small  vein.  Further  outwards,  towards  the  mastoid  portion  of  the 
bone,  is  a  small  slit,  almost  hidden  by  a  thin  plate  of  bone ;  this  is 
the  aquceductus  vestibuli,  and  transmits  a  small  artery  and  vein  of 
the  vestibule  and  a  process  of  dura  mater.  Below  the  meatus,  and 
partly  concealed  by  the  margin  of  the  posterior  border  of  the  bone, 
is  the  aqucBductus  cochlece,  through  which  passes  a  vein  from  the 
cochlea  to  the  internal  jugular  vein  and  a  process  of  dura  mater. 

The  basilar  surface  is  rough  and  irregular,  and  enters  into  the 
formation  of  the  under  surface  of  the  base  of  the  skull.  Projecting 
downwards,  near  its  middle,  is  a  long  sharp  spine, — the  styloid  pro- 
cess,— occasionally  connected  with  the  bone  only  by  cartilage,  and 
lost  during  maceration,  particularly  in  the  young  subject.  At  the 
base  of  this  process  is  a  rough  sheath-like  ridge,  into  which  the 
styloid  process  appears  implanted,  the  vaginal  process.  In  front  of 
the  vaginal  process  is  a  broad  triangular  depression,  the  glenoid 
fossa,  bounded  in  front  by  the  eminentia  articularis,  behind  by  the 
vaginal  process,  and  externally  by  the  rough  lip  of  the  processus 
auditorius. 

This  fossa  is  divided  transversely  by  the  glenoid  fissure  (fissura 
Glaseri)  which  lodges  the  extremity  of  the  processus  gracilis  of  the 
malleus,  and  transmits  the  laxator  tympani  muscle,  chorda  tympani 
nerve,  and  anterior  tympanic  artery.  The  surface  of  the  fossa  in 
front  of  this  fissure  is  smooth,  to  articulate  with  the  condyle  of  the 
lower  jaw ;  and  that  behind  the  fissure  is  rough,  for  the  reception 
of  a  part  of  the  parotid  gland.  At  the  extremity  of  the  inner  angle 
of  the  glenoid  fossa  is  the  foramen  for  the  Eustachian  tube ;  and 
separated  from  it  by  a  thin  lamella  of  bone,  called  processus  cochlea- 
riformis,  is  a  small  canal  for  the  transmission  of  the  tensor  tympani 
muscle.  Directly  behind,  and  at  the  root  of  the  styloid  process,  is 
the  stylo-mastoid  foramen,  the  opening  of  exit  to  the  facial  nerve, 
and  of  entrance  to  the  stylo-mastoid  artery.  Nearer  to  the  apex  of 
the  bone  is  a  large  oval  opening,  the  carotid  foramen — the  com- 
mencement of  the  carotid  canal,  which  lodges  the  internal  carotid 
artery  and  the  carotid  plexus.     And  between  the  stylo-mastoid  and 


40  SPHENOIDAL  BONE. 

carotid  foramen  in  the  posterior  border,  is  an  irregular  excavation 
forming  part  of  the  jugular  fossa,  and  divided  into  two  parts  by  a 
ridge  and  a  sharp  spine,  the  jugular  process.  Upon  this  ridge,  at 
the  posterior  margin  of  the  carotid  foramen,  is  a  small  opening 
leading  into  the  canal  which  transmits  the  tympanic  branch  of  the 
glosso-pharyngeal  nerve  (Jacobson's  nerve). 

Borders. — The  superior  border  is  sharp,  and  gives  attachment  to 
the  tentorium  cerebelli.  It  is  grooved  for  the  superior  petrosal 
sinus,  and  near  its  extremity  is  marked  by  a  smooth  notch  upon 
which  reclines  the  fifth  nerve. 

The  anterior  border  is  grooved  for  the  Eustachian  tube,  and 
forms  the  posterior  boundary  of  the  foramen  lacerum  basis  cranii ; 
by  its  sharp  extremity  it  gives  attachment  to  the  tensor  tympani 
and  levator  palati  muscles.  The  posterior  border  is  gi'ooved  for  the 
inferior  petrosal  sinus,  and  excavated  for  the  jugular  fossa ;  it  forms 
the  anterior  boundary  of  the  foramen  lacerum  posterius. 

Developement. — By  five  centres ;  one  for  the  squamous  portion, 
one  for  the  mastoid,  one  for  the  petrous  portion,  one  for  the  audi- 
tory process,  and  one  for  the  styloid  process. 

Articulations. — With  Jive  bones ;  occipital,  parietal,  sphenoid,  in- 
ferior maxillary,  and  malar. 

.Attachment  of  Muscles. — To  fourteen  ;  by  the  squamous  portion, 
to  the  temporal ;  by  the  zygoma,  to  the  masseter ;  by  the  mastoid 
portion,  to  the  occipito-frontaHs,  splenius  capitis,  sterno-mastoid, 
trachelo-mastoid,  digasticus  and  retrahens  aurem ;  by  the  styloid 
process,  to  the  stylo-pharyngeus,  stylo-hyoideus,  stylo-glossus,  and 
two  ligaments — the  stylo-hyoid  and  stylo-maxillary;  and  by  the 
petrous  portion,  to  the  levator  palati,  tensor  tympani,  and  stapedius. 

Sphenoidal  Bone. — The  sphenoid  (rfcp^v,  a  wedge)  is  an  irregular 
bone  situated  at  the  base  of  the  skull,  wedged  between  the  other 
bones  of  the  cranium,  and  entering  into  the  formation  both  of  the 
cranium  and  face.  It  bears  some  resemblance  in  form  to  a  bat 
with  its  wings  extended,  and  is  divisible  into  body,  wings,  and  pro- 
cesses. 

The  body  forms  the  central  mass  of  the  bone,  from  which  the 
wings  and  processes  are  projected.  From  the  upper  and  anterior 
part  of  the  body  extend  on  each  side  two  small  triangular  plates, — 
the  lesser  wings ;  from  either  side  and  expanding  laterally  are  the 
greater  wings ;  proceeding  backwards  from  the  base  of  the  greater 
wings,  the  spinous  processes ;  and  downwards,  the  pterygoid  pro- 
cesses. 

The  body  presents  for  examination  a  superior  or  cerebral  sur- 
face, an  antero-infcrior  surface,  and  a  posterior  surface. 

Superior  Surface. — At  the  anterior  extremity  of  this  surface  is  a 
small  projecting  plate,  the  ethmoidal  spine,  and  spreading  out  on 
either  side  the  lesser  wings.  Behind  the  ethmoidal  spine  in  the 
middle  line  is  a  rounded  elevation,  the  olivary  process,  which  sup- 
ports the  commissure  of  the  optic  nerves.  Passing  outwards  and 
forwards  from  the  olivary  process,  are  the  optic  foramina,  which 
transmit  the  optic  nerves  and  ophthalmic;  arteries.     Behind  the  optic 


SPHENOID  BONE.  41 

foramina  are  two  sharp  tubercles,  the  anterior  clinoid  processes, 
which  are  the  inner  termination  of  the  lesser  wings.  Beneath  these 
processes,  on  the  sides  of 

the   olivary   process,   are  '  ^^S- 16* 

two  depressions!  fo^  ^he 

last   turn  of  the  internal       /^^%-rSn  "^"^f-^J^v 

carotid   arteries.     Behind         '^''^^     '  ^-     -  . 

the  olivary  process,  is  the 
sella  Turcica,  the  deep 
fossa  which  lodges  the 
pituitary  gland  and  cir- 
cular sinus ;  behind  and 
somewhat  overhanging 
the  sella  Turcica,  is  a 
broad  rough  plate,  bound- 
ed at  each  angle  by  a  tubercle,  the  'posterior  clinoid  processes ;  and 
behind  this  plate  an  inclining  surface,  w^hich  is  continuous  with  the 
basilar  process  of  the  occipital  bone.  On  either  side  of  the  sella 
Turcica  is  a  broad  groove  {carotid)  which  lodges  the  internal 
carotid  artery,  the  cavernous  sinus,  and  its  nerves.  Immediately 
external  to  this  groove,  at  the  junction  of  the  greater  wings  with 
the  body,  are  four  foramina :  the  first  is  a  broad  interval,  the  sphe- 
noidal fissure,  which  separates  the  greater  and  lesser  wings,  and 
transmits  the  third,  fourth,  the  three  branches  of  the  ophthalmic 
division  of  the  fifth  and  the  sixth  nerves,  and  the  ophthalmic  vein. 
Behind  and  beneath  this  fissure  is  the  foramen  rotundum  for  the 
superior  maxillary  nerve ;  and  still  farther  back,  in  the  base  of  the 
spinous  process,  the  foramen  ovale  for  the  inferior  maxillary  nerve, 
arteria  meningea  parva,  and  nervus  petrosus  superficialis  minor. 
Behind  the  foramen  ovale,  near  the  apex  of  the  spinous  process,  is 
the  foramen  spinosum  for  the  arteria  meningea  magna. 

*  The  superior  or  cerebral  surface  of  the  sphenoid  bone.  1.  The  processus  olivaris. 
2.  The  ethmoidal  spine.  3.  The  lesser  wing-  of  the  left  side.  4.  The  cerebral  sur- 
face of  the  greater  wing  of  the  same  side.  5.  The  spinous  process.  6.  The  extremity 
of  the  pterygoid  process  of  the  same  side,  projecting  downwards  from  the  under  sur- 
face of  the  body  of  the  bone.  7.  The  foramen  opticum.  8.  The  anterior  clinoid  pro- 
cess. 9.  The  groove  by  the  side  of  the  sella  Turcica ;  for  lodging  the  internal  carotid 
artery,  cavernous  plexus,  cavernous  sinus,  and  orbital  nerves.  10.  The  sella  Turcica. 
11.  The  posterior  boundary  of  the  sella  Turcica;  its  projecting  angles  are  the  pos 
terior  clinoid  processes.  12.  The  basilar  portion  of  the  bone.  13.  Part  of  the  sphe- 
noidal fissure.  14.  The  foramen  rotundum.  15.  The  foramen  ovale,  16.  The  fora- 
men spinosum.  17.  The  angular  interval  which  receives  the  apex  of  the  petrous  portion 
of  the  temporal  bone.  The  posterior  extremity  of  the  Vidian  canal  terminates  at  this 
angle.  18.  The  spine  of  tlie  spinous  process;  it  affords  attachment  to  the  internal 
lateral  ligament  of  tlie  lower  jaw.  19.  The  border  of  the  greater  wing  and  spinous 
process  which  articulates  with  the  anterior  part  of  the  squamous  portion  of  the  tem- 
poral bone.  20.  The  internal  border  of  the  spinous  process,  which  assists  in  the 
formation  of  the  foramen  laeerum  basis  cranii.  21.  That  portion  of  tlie  greater  ala 
which  articulates  with  the  anterior  inferior  angle  of  the  parietal  bone.  22.  The  por- 
tion of  the  greater  ala  which  articulates  with  the  orbital  process  of  the  frontal  bone. 

t  These  depressions  are  occasionally,  as  in  a  skull  before  me,  converted  into  fora- 
mina by  the  extension  of  a  short  bony  pillar  from  the  anterior  clinoid  process  to  the 
body  of  tlie  sphenoid. 

6 


42 


SPHENOID  BONE. 


Upon  the  aniero-inferior  surface  is  a  long  flattened  spine,  the 
rostrum,  which  articulates  with  the  vomer ;  and  on  each  side  of  the 

rostrum  an  irregular  opening, 
Fig.  17*  leading    into   the    sphenoidal 

cells  :  these  openings  are  par- 
tially closed  by  two  thin  plates 
of  bone  (frequently  broken 
away),  the  sphenoidal  spongy 
bones.  On  each  side  of  the 
sphenoidal  cells  are  the  out- 
lets of  the  optic  foramina, 
sphenoidal  fissures,  and  fora- 
mina rotunda,  the  lesser  and 
greater  wings ;  and  below, 
the  pterygoid  processes. 
Upon  the  under  surface  of  the  body  are  two  small  fissures,  con- 
verted into  canals  by  the  vomer,  the  pterygo-palaiine  canals,  which 
transmit  the  pterygo-palatine  arteries ;  and  traversing  the  roots  of 
the  pterygoid  at  their  union  with  the  body,  two  pterygoid  or  Vidian 
canals,  which  give  passage  to  the  Vidian  nerve  and  artery  at  each 
side.  The  posterior  surface  is  flat  and  rough,  and  articulates  with 
the  basilar  process  of  the  occipital  bone.  In  the  adult  this  union  is 
usually  completed  by  bone;  from  which  circumstance  the  sphenoid, 
in  conjunction  with  the  occipital,  was  described  by  Soemmering 
and  Meckel  as  a  single  bone,  under  the  name  of  spheno-occipilal  or 
basilar  bone.  This  surface  is  continuous  on  each  side  with  the 
spinous  process,  and  at  the  angle  of  union  is  the  termination  of  the 
Vidian  canal  or  foramen  pterygoideum. 

The  lesser  wings  (processes  of  Ingrassias)  are  thin  and  triangular, 
the  base  being  attached  to  the  upper  and  anterior  part  of  the  body 
of  the  sphenoid,  and  the  apex  extended  outwards,  and  terminating 
in  an  acute  point.  The  anterior  border  is  irregularly  serrated,  the 
posterior  being  free  and  rounded,  and  received  into  the  fissure  of 
Sylvius  of  the  cerebrum.  The  inner  extremity  of  this  border  forms 
the  anterior  clinoid  process,  which  is  supported  by  a  short  pillar  of 
bone,  giving  attachment  to  a  part  of  the  common  tendon  of  the 
muscles  of  the  orbit.  The  lesser  wing  forms  the  posterior  part  of 
the  roof  of  the  orbit,  and  its  base  is  traversed  by  the  optic  foramen. 
The  greater  wings  present  three  surfaces  ;  a  superior  or  cerebral, 
which  forms  part  of  the  middle  fossa  of  the  base  of  the  skull,  an 

*  The  antcro-inferior  view  of  the  sphenoid  hone.  1.  The  ethmoid  spine.  2.  Tiie 
rostrum.  3.  Tiic  sphenoidal  sponfry  bone,  partly  closing  the  left  opening  of  the  sphe- 
noidal ccUs.t  4.  The  lesser  wing.  .'>.  'I'lie  foramen  opticum  piereing  the  bnse  of  the 
lesser  wing.  6.  The  sphenoidal  fissure.  7.  Tlic  foramen  rotundiun.  8.  The  orbital 
surface  of  the  greater  wing.  9.  Its  temporal  surface.  10.  The  pterygoid  ridge. 
11.  The  pterygo-pahitine  canal.  12.  The  foramen  of  entrance  to  the  Vidian  canal. 
13.  Tlie  internal  pterygoid  plate.  M.  The  hamnhir  process.  1.5.  The  external 
pterygoid  plate.  Ifj.  Tlie  foramen  spinosum.  17.  The  foramen  ovale.  18.  The 
extremity  of  the  spinous  process  of  the  sphenoid. 

+  This  is  a  part  of  the  pyramid  of  Wistar.    See  description  of  elhnioid. 


SPHENOID    BONE,  43 

anterior  surface  which  assists  in  forming  the  outer  wall  of  the  orbit, 
and  an  external  surface,  divided  into  two  parts  by  the  pterygoid 
ridge.  The  superior  part  of  the  external  surface  enters  into  the 
formation  of  the  temporal  fossa,  and  the  inferior  portion  forms  part 
of  the  zygomatic  fossa.  The  pterygoid  ridge,  dividing  the  two, 
gives  attachment  to  the  upper  origin  of  the  pterygoideus  externus 
muscle. 

The  spinous  processes  project  backwards  at  each  side  from  the 
base  of  the  greater  wings  of  the  sphenoid,  and  are  received  into  the 
angular  intervals  between  the  squamous  and  petrous  portions  of  the 
temporal  bones.  Piercing  the  base  of  each  process  is  a  large  oval 
opening,  the  foramen  ovale ;  nearer  its  apex  a  smaller  opening,  the 
foramen  spinosum ;  and  extending  downwards  from  the  apex  a  short 
spine,  which  gives  attachment  to  the  internal  lateral  ligament  of  the 
lower  jaw  and  to  the  laxator  tympani  muscle.  The  external  border 
of  the  spinous  process  is  rough,  to  articulate  with  the  lower  border 
of  the  squamous  portion  of  the  temporal  bone ;  the  internal  forms 
the  anterior  boundary  of  the  foramen  lacerum  basis  cranii,  and  is 
somewhat  grooved  for  the  reception  of  the  Eustachian  tube. 

The  pterygoid  processes  descend  perpendicularly  from  the  base  of 
the  greater  wings,  and  form  in  the  articulated  skull  the  lateral  boun- 
daries of  the  posterior  nares.  Each  process  consists  of  an  external 
and  internal  plate,  and  an  anterior  surface.  The  external  plate  is 
broad  and  thin,  giving  attachment,  by  its  external  surface,  to  the 
external  pterygoid  muscle,  and  by  its  internal  surface  to  the  internal 
pterygoid.  This  plate  is  sometimes  pierced  by  a  foramen,  which  is 
frequently  formed  by  a  process  of  communication  passing  between 
it  and  the  spinous  process.  The  internal  pterygoid  plate  is  long 
and  narrow,  and  terminated  at  its  extremity  by  a  curved  hook,  the 
hamular  process,  around  which  plays  the  tendon  of  the  tensor  palati 
muscle.  At  the  base  of  the  internal  pterygoid  plate  is  a  small 
oblong  depression,  the  scaphoid  fossa,  from  which  arises  the  cir- 
cumflexus,  or  tensor  palati  muscle.  The  interval  between  the 
two  pterygoid  plates  is  the  pterygoid  fossa ;  and  the  two  plates  are 
separated  inferiorly  by  an  angular  notch  {palatine),  which  receives 
the  tuberosity,  or  pterygoid  process,  of  the  palate  bone.  The  ante- 
rior surface  of  the  pterygoid  process  is  broad  near  its  base,  and 
supports  Meckel's  ganglion.  The  base  of  the  process  is  pierced  by 
the  Vidian  canal. 

Developement. — By  twelve  centres  ;  four  for  the  body,  viz,  two  for 
its  anterior,  and  two  for  its  posterior  part ;  four  for  the  wings  ;  two 
for  the  external  pterygoid  plates,  and  two  for  the  sphenoidal  spongy 
bones. 

Articulations. — With  twelve  bones  ;  all  the  bones  of  the  head  and 
five  of  the  face,  viz.  the  two  malar,  two  palate,  and  the  vomer. 

Attachment  of  Muscles. — To  twelve  pairs;  temporal,  external  ptery- 
goid, internal  pterygoid,  superior  constrictor,  tensor  palati,  laxator 
tympani,  levator  palpebras,  obliquus  superior,  superior  rectus,  internal 
rectus,  inferior  rectus,  and  external  rectus. 


44  ETHMOID  BOiVE. 

Ethmoid  Bone. — The  ethmoid  (^i^i^oj,  a  sieve)  is  a  square-shaped 
cellular  bone,  situated  between  the  two  orbits,  at  the  root  of  the  nose, 
and  perforated  upon  its  upper  surface  by  a  number  of  small  open- 
ings, from  which  pecuHarity  it  has  received  its  name.  It  consists  of 
a  perpendicular  lamella  and  two  lateral  masses. 

The  "perpendicular  lamella  is  a  thin  central  plate,  which   arti- 
culates with  the   vomer  and  cartilage  of 
^*     ■  the  septum,  and  assists  in  forming  the  sep- 

tum of  the  nose.  It  is  surmounted  supe- 
riorly by  a  thick  and  strong  process,  the 
crista  galli,  which  projects  into  the  cavity 
of  the  skull,  and  gives  attachment  to  the 
falx  cerebri.  On  each  side  of  the  crista 
galh,  upon  the  upper  surface  of  the  bone, 
is  a  thin  and  grooved  plate,  perforated  by 
a  number  of  small  openings,  the  cribriform 
lamella,  which  supports  the  bulb  of  the 
olfactory  nerve,  and  gives  passage  to  its 
filaments,  and  to  the  internal  nasal  nerve. 
The  cribriform  lamella  serves  to  connect  masses  with  the  perpen- 
dicular plate. 

The  lateral  masses  are  divisible  into  an  internal  and  external  sur- 
face, and  four  borders — superior,  inferior,  anterior,  and  posterior. 
The  internal  surface  is  rough  and  slightly  convex,  and  forms  the 
external  boundary  of  the  upper  part  of  the  nasal  fossae.  Towards 
the  posterior  border  of  this  surface  is  a  narrow  horizontal  fissure, — 
the  superior  meatus  of  the  nose, — the  upper  margin  of  which  is  thin, 
and  somewhat  curled  inwards  ;  hence  it  is  named  the  superior  tur- 
binated bone.  Below  the  meatus  is  the  convex  surface  of  another 
thin  plate  which  is  curled  outwards,  and  forms  the  lower  border  of 
the  mass,  the  middle  turbinated  bone.  The  external  surface  is  quad- 
rilateral and  smooth,  hence  it  is  named  os  planum ;  it  enters  into  the 
formation  of  the  inner  wall  of  the  orbit. 

The  superior  border  is  irregular  and  cellular,  the  cells  being  com- 
pleted by  the  edges  of  the  ethmoidal  fissure  of  the  frontal  bone.  This 
border  is  crossed  by  two  grooves,  sometimes  complete  canals,  open- 
ing into  the  orbit  by  the  anterior  and  posterior  ethmoidal  foramina. 
The  inferior  border  is  formed  internally  by  the  lower  border  of  the 
middle    turbinated  bone,  and   externally  by  a   concave  irregular 

*  The  ethmoid  bone  seen  from  above  and  behind.  1.  The  central  lamella.  2,2. 
The  lateral  masses ;  the  numbers  are  placed  on  the  posterior  border  of  the  lateral  mass 
at  each  side.  .3.  The  crista  galli  process.  4.  Tlic  eribrifrom  plate  of  tlie  left  side, 
pierced  by  the  cribriform  foramina.  5.  The  hollow  space  immediately  above  and  to 
the  left  of  this  number  is  the  superior  meatus.  G.  The  superior  turbinated  bono.  7. 
The  middle  turbinated  bone  ;  the  numbers  5,  G,  7,  are  situated  upon  the  internal  sur- 
face  of  the  loft  lateral  mass,  near  its  posterior  part.  The  interval  between  these  parts 
is  the  superior  meatus.  8.  Tlic  external  surface  of  the  lateral  mass,  or  os  planum.  9. 
The  superior  or  frontal  border  of  the  lateral  mass,  jrrooved  by  the  anterior  and  poste- 
rior ethmoidal  canals.  10.  Refers  to  tlie  concavity  of  the  middle  turbinated  bone, 
which  is  the  upper  boundary  of  the  middle  meatus. 


NASAL  BONES.  45 

fossa,  the  upper  boundary  of  the  middle  meatus.  The  anterior  border 
presents  a  number  of  incomplete  cells,  which  are  closed  by  the 
superior  maxillary  and  lachrymal  bones ;  and  the  -posterior  border  is 
irregularly  cellular,  to  articulate  with  the  sphenoid  and  palate  bones.* 

The  lateral  masses  are  composed  of  cells,  which  are  divided  by  a 
thin  partition  into  anterior  and  posterior  ethmoidal  cells.  The  ante- 
rior, the  most  numerous,  communicate  with  the  frontal  sinuses,  and 
open  by  means  of  an  irregular  and  incomplete  tubular  canal,  the 
infundibulum,  into  the  middle  meatus.  The  posterior  cells,  fewer  in 
number,  open  into  the  superior  meatus. 

Vevelopement — By  three  centres  ;  one  for  each  lateral  mass,  and 
one  for  the  perpendicular  lamella. 

Articulations. — With  thirteen  bones  ;  two  of  the  cranium, — the 
frontal  and  sphenoid;  the  rest  of  the  face,  viz.  the  nasal,  superior 
maxillary,  lachrymal,  palate,  the  inferior  turbinated,  and  the  vomer. 

No  muscles  are  attached  to  this  bone. 


BONES  OF  THE  FACE. 

The  face  is  composed  of  fourteen  bones  ;  viz.  the 
Two  nasal.  Two  palate. 

Two  superior  maxillary,  Two  inferior  turbinated, 

Two  lachrymal,  Vomer, 

Two  malar.  Inferior  maxillary. 

Nasal  Bones. — The  nasal  (fig.  23)  are  two  small  quadrangular 
bones,  forming  by  their  union  the  bridge  and  base  of  the  nose. 
Upon  the  upper  surface  they  are  convex,  and  pierced  by  a  foramen, 
for  a  small  artery ;  on  the  under  surface  they  are  somewhat  con- 
cave, and  marked  by  a  groove,  which  lodges  the  nasal  branch  of 
the  ophthalmic  nerve.  The  superior  border  is  narrow  and  thick,  the 
inferior  broad,  thin,  and  irregular. 

Developement. — By  a  single  centre  for  each  bone. 

Articulations. — With  four  bones  ;  frontal,  ethmoidal,  nasal,  and 
superior  maxillary. 

Attachment  of  Muscles. — It  has  in  relation  with  it  the  pyramidalis 
nasi,  and  compressor  nasi ;  but  neither  of  these  muscles  is  inserted 
into  it. 

Superior  Maxillary  Bones. — The  superior  maxillary  arc  the 
largest  bones  of  the  face,  with  the  exception  of  the  lower  jaw ;  they 
form,  by  their  union,  the  whole  of  the  upper  jaw,  and  assist  in  the 
construction  of  the  nose,  the  orbit,  the  cheek,  and  the  palate.  Each 
bone  is  divisible  into  a  body  and  four  processes. 

*  Mr.  Wilson  has  entirely  omitted  the  description  of  the  pyramids  of  Wrslnr,  which 
in  their  early  stage  project  as  thin  triangular  laniinre  from  the  posterior  borders  of  the 
lateral  masses.  As  they  become  developed  the  edges  of  the  laminte  fold  over  so  as  to 
form  an  imperfect  triangular  pyramid,  encroacliing  upon  the  body  of  the  sphenoid 
bone  on  its  under  surface,  and  finally  coalescing  with  it  so  as  to  perfect  the  sphenoidal 
cells.  The  remains  of  these  pyramids  mny  be  seen  on  the  adult  bone,  and  are  called 
by  Wilson  the  sphenoidal  spongy  bones.  They  were  first  studied  by  Professor  Wistar, 
and  are  called  after  him.  G. 


46 


SUPERIOR  MAXILLARY  BONES. 


The  body  is  triangular  in  form,  and  hollowed  in  its  interior  into 
a  large  cavity,  the  antrum  maxillare  (antrum  of  Highmore).  It 
presents  for  examination  three  sides ;  an  external  or  facial,  internal 
or  nasal,  and  a  posterior  or  zygomatic,  and  a  superior  surface — the 
orbital.  "  The  external  or  facial  surface  forms  the  anterior  part  of 
the  bone ;  it  is  irregularly  concave,  and  pre- 
sents a  deep  depression  towards  its  centre, 
— the  canine  fossa,  which  gives  attachment  to 
two  muscles,  the  compressor  nasi  and  levator 
anguli  oris.  Immediately  above  this  fossa 
is  the  infra-orhital  foramen, — the  termination 
of  the  infra-orbital  canal, — transmitting  the 
superior  maxillary  nerve,  and  infra-orbital 
artery ;  and  above  the  infra-orbital  foramen, 
the  lower  margin  of  the  orbit,  continuous 
externally  with  the  rough  articular  surface 
of  the  malar  process,  and  internally  with  a 
thick  ascending  plate,  the  nasal  process. 
Towards  the  middle  line  of  the  face  this 
surface  is  bounded  by  the  concave  border 
of  the  opening  of  the  nose,  which  is  projected  forwards  at  its  in- 
ferior termination  into  a  sharp  process,  forming,  with  a  similar  pro- 
cess of  the  opposite  bone,  the  nasal  spine.  Beneath  the  nasal  spine, 
and  above  the  two  superior  incisor  teeth,  is  a  slight  depression,  the 
incisive  or  myrtiformfossa,  which  gives  origin  to  the  depressor  labii 
superioris  alaeque  nasi  muscle.  The  myrtiform  fossa  is  divided 
from  the  canine  fossa  by  a  perpendicular  ridge,  corresponding  with 
the  direction  of  the  root  of  the  canine  tooth.  The  inferior  boundary 
of  the  facial  surface  is  the  alveolar  process  which  contains  the 
teeth  of  the  upper  jaw,  and  it  is  separated  from  the  zygomatic  sur- 
face by  a  strong  projecting  eminence,  the  malar  process.  The  in- 
ternal, or  nasal  surface,  presents  a  large  irregular  opening,  leading 
into  the  antrum  maxillare ;  this  opening  is  nearly  closed  in  the  ar- 
ticulated skull  by  the  ethmoid,  palate,  lachrymal,  and  inferior  turbi- 
nated bones.  The  cavity  of  the  antrum  is  somewhat  triangular, 
corresponding  in  shape  with  the  form  of  the  body  of  the  bone. 
Upon  its  internal  surface  are  numerous  grooves,  lodging  branches 
of  the  superior  maxillary  nerve,  and  projecting  into  its  floor  several 
conical  processes,  corresponding  with  the  roots  of  the  jEirst  and 
second  molar  teeth.     In  front  of  the  opening  of  the  antrum  is  the 


*  The  superior  maxillary  bones  of  the  right  side,  as  seen  from  the  lateral  aspect.  1. 
The  externa],  or  facial  surface ;  the  depression  in  which  the  iigure  is  placed  is  tlie 
canine  fossa.  2.  The  posterior,  or  zygomatic  surface.  3.  The  superior,  or  orbital  sur- 
face. 4.  The  infra-orbital  foraraen  ;  it  is  situated  immediately  below  the  number.  5. 
The  infra-orbital  canal,  leading  to  the  infra-orbital  foramen.  G.  The  inferior  border  of 
the  orbit.  7.  The  malar  process.  8.  The  nasal  process.  9.  The  concavity  forming 
the  lateral  boundary  of  the  anterior  narcs.  10.  The  nasal  spine.  11.  The  incisive,  or 
myrtiform  fossa.  12.  The  alveolar  process.  1.3.  The  internal  border  of  the  orbital 
surface,  which  articulates  with  the  ethmoid  and  jjalatc  bone.  14.  Tiie  concavity  which 
articulates  with  the  lachrymal  bone,  and  forms  the  commencement  of  the  nasal  duct. 
1.5.  The  palute  prof.c-:s.  i.  TIjc  two  incisor  teeth,  c.  The  canine.  6.  The  two  bicus- 
pidati.     m.  The  tJiree  molares. 


SUPERIOE  MAXILLARY  BONES.  47 

Strong  ascending  plate  of  the  nasal  process,  marked  inferiorly  by  a 
rough  horizontal  ridge,  which  gives  attachment  to  the  inferior  tur- 
binated bone.  The  concave  depression  immediately  above  this 
ridge  corresponds  with  the  middle  meatus  of  the  nose,  and  that  below 
the  ridge  with  the  inferior  meatus.  Between  the  nasal  process  and 
the  opening  of  the  antrum,  is  a  deep  groove,  which  is  converted 
into  a  canal  by  the  lachrymal  bone,  and  constitutes  the  nasal  duct 
or  ductus  ad  nasum.  The  superior  border  of  the  nasal  surface  is 
irregularly  cellular,  and  articulates  with  the  lachrymal  and  ethmoid 
bone ;  the  posterior  border  is  rough,  and  articulates  with  the  palate 
bone ;  the  anterior  border  is  sharp,  and  forms  the  free  margin  of  the 
opening  of  the  nose ;  and  from  the  inferior  border  projects  inwards 
a  strong  horizontal  plate,  the  palate  process. 

The  posterior  surface  may  be  called  zygomatic,  from  forming  part  of 
the  zygomatic  fossa ;  it  is  bounded  externally  by  the  malar  process, 
and  internally  by  a  rough  and  rounded  border,  the  tuberosity, 
which  is  pierced  by  a  number  of  small  foramina,  giving  passage  to 
the  posterior  dental  nerves  and  branches  of  the  superior  dental 
artery.  The  lower  part  of  this  tuberosity  presents  a  rough  oval 
surface,  to  articulate  with  the  palate  bone,  and  immediately  above 
and  to  the  inner  side  of  this  articular  surface  a  smooth  groove, 
which  forms  part  of  the  posterior  palatine  canal.  The  superior 
border  is  smooth  and  rounded  to  form  the  lower  boundary  of  the 
spheno-maxillary  fissure,  and  is  marked  by  a  notch,  the  commence- 
ment of  the  infra-orbital  canal.  The  inferior  boundary  is  the 
alveolar  process,  containing  the  two  last  molar  teeth. 

The  orbital  surface  is  triangular  and  thin,  and  constitutes  the 
floor  of  the  orbit.  It  is  bounded  internally  by  an  irregular  edge, 
which  articulates  with  the  palate,  ethmoid,  and  lachrymal  bone ; 
posteriorly,  by  the  smooth  border  which  enters  into  the  formation 
of  the  spheno-maxillary  fissure ;  and  anteriorly,  by  a  convex 
margin,  partly  smooth  and  partly  rough,  the  smooth  portion  forming 
part  of  the  lower  border  of  the  orbit,  and  the  rough  articulating 
with  the  malar  bone.  The  middle  of  this  surface  is  channelled  by 
a  deep  groove  and  canal,  the  infra-orbital,  which  terminates  at  the 
infra-orbital  foramen. 

The  four  processes  of  this  bone  are,  the  nasal,  malar,  alveolar, 
and  palate. 

The  nasal  process  ascends  by  the  side  of  the  nose,  to  which  it 
forms  the  lateral  boundary,  and  articulates  with  the  frontal  and 
nasal  bone. 

By  its  external  surface  it  gives  attachment  to  the  levator  labii 
superioris  aleeque  nasi,  and  to  the  orbicularis  palpebrarum  muscle ; 
its  internal  surface  contributes  to  form  the  inner  wall  of  the  nares, 
and  the  posterior  border  is  thick  and  hollowed  into  a  groove  for  the 
nasal  duct.  The  margin  of  the  nasal  process,  which  is  continuous 
with  the  lower  border  of  the  orbit,  is  sharp  and  marked  by  a  small 
tubercle  which  serves  as  a  guide  to  the  introduction  of  the  knife  in 
the  operation  for  fistula  lachrymalis. 

The  malar  process,  large  and  irregular,  is  situated  at  the  angle 


48  LACHRYMAL  BONES, 

of  separation  between  the  facial  and  zygomatic  surfaces,  and  pre- 
sents a  large  triangular  surface  for  articulation  with  the  malar  bone. 

The  alveolar  process  forms  the  lower  margin  of  the  bone ;  it  is 
spongy  and  cellular  in  textm'e,  and  excavated  into  deep  holes  for 
the  reception  of  the  teeth. 

The  palate  process  is  thick  and  strong,  and  projects  horizontally 
inwards  from  the  inner  surface  of  the  body  of  the  bone.  Superiorly, 
it  is  concave,  and  forms  the  floor  of  the  nares ;  inferiorly,  it  is  also 
concave,  and  assists  in  the  formation  of  the  roof  of  the  palate. 
Its  internal  edge  is  raised  into  a  ridge,  which,  with  a  corresponding 
ridge  in  the  opposite  bone,  forms  a  groove  for  the  reception  of  the 
vomer.  At  the  anterior  extremity  of  its  nasal  surface  is  a  foramen, 
which  leads  into  a  canal  formed  conjointly  by  the  two  superior 
maxillary  bones, — the  naso-palatine  canal.  The  termination  of 
this  canal  is  situated  immediately  behind  the  incisor  teeth,  hence  it 
is  also  named  the  incisive  foramen.* 

Developement — By  six  centres ;  one  for  the  body,  one  for  each 
of  the  three  processes,  nasal,  malar,  and  palate ;  and  two  for  the 
alveolar  process. 

Articulations. — With  nine  bones,  viz.  with  two  of  the  cranium 
and  with  all  the  bones  of  the  face,  excepting  the  inferior  maxillary. 
These  are,  the  frontal  and  ethmoid,  nasal,  lachrymal,  malar, 
inferior  turbinated,  palate,  vomer,  and  with  its  fellow  of  the  oppo- 
site side. 

Attachment  of  Muscles. — To  nine;  orbicularis  palpebrarum,  obli- 
quus  inferior  oculi,  levator  labii  superioris  alseque  nasi,  levator  labii 
superioris  proprius,  levator  anguli  oris,  compressor  nasi,  depressor 
labii  superioris  alajque  nasi,  buccinator,  masseter. 

Lachrymal  Bones — (os  unguis,  from  an  imagined  resemblance 
to  a  finger  nail).  The  lachrymal  (fig.  23)  is  a  thin  oval-shaped 
plate  of  bone,  situated  at  the  anterior  and  inner  angle  of  the  orbit. 
It  may  bo  divided  into  an  external  and  internal  surface  and  borders. 
The  external  surface  is  smooth  and  marked  by  a  vertical  ridge, — 
the  lachrymal  crest, — into  two  portions,  one  of  which  is  flat  and 
enters  into  the  formation  of  the  orbit,  hence  may  be  called  the 
orbital  portion;  the  other  is  concave,  and  lodges  the  lachrymal 
sac,  hence  the  lachrymal  portion.  The  internal  surface  is  rough 
and  completes  the  anterior  ethmoid  cells,  it  assists  in  forming  the 
wall  of  the  nasal  fossa:  and  nasal  duct. 

Developement. — By  a  single  centre. 

Articulations. — Wiihfour  bones;  two  of  the  cranium,  frontal  and 
ethmoid  ;  and  two  of  the  face,  superior  maxillary,  and  inferior 
turbinated  bone. 

Attaclirnent  of  Muscles. — To  one  muscle,  the  tensor  tarsi,  and  to 
an  expansion  of  the  tcndo  oculi,  the  former  arising  from  the  orbital 
surface,  the  other  being  attached  to  the  lachrymal  crest. 

Malar  Bones — (mala,  the  cheek).  The  malar  (fig.  23)  is  the 
strong   quadrangular  bone   which  forms   the  pi-ominence   of  the 

*  It  contains  a  ganglion  from  the  fifth  pair.     G. 


PALATE  BONES. 


49 


cheek.  It  is  divisible  into  an  external  and  internal  surface,  and 
four  processes,  the  frontal,  orbital,  maxillary,  and  zygomatic.  The 
external  surface  is  smooth  and  convex,  and  pierced  by  several 
small  openings  which  give  passage  to  filaments  of  the  temporo- 
malar  nerve  and  minute  arteries.  The  internal  surface  is  concave, 
partly  smooth  and  partly  rough;  smooth  where  it  forms  part  of - 
the  temporal  fossa,  and  rough  where  it  articulates  with  the  superior 
maxillary  bone. 

The  frontal  process  ascends  perpendicularly  to  form^  the  outer 
border  of  the  orbit,  and  articulate  with  the  external  angular  process 
of  the  frontal  bone.  The  orbital  process  is  a  thick  plate,  which  pro- 
jects inwards  from  the  frontal  process,  and  unites  with  the  great 
ala  of  the  sphenoid  to  constitute  the  outer  wall  of  the  orbit.  It  is 
pierced  by  several  small  foramina  for  the  passage  of  temporo-malar 
filaments  of  the  superior  maxillary  nerve.  The  maxillary  process 
is  broad,  and  articulates  with  the  superior  maxillary  bone.  The 
zygomatic  process,  narrower  than  the  rest,  projects  backwards  to 
unite  with  the  zygoma  of  the  temporal  bone. 
Developement. — By  a  single  centre. 

Articulations. — With  four  bones ;  three  of  the  cranium,  frontal, 
temporal,  and  sphenoid ;  and  one  of  the  face,  the  superior  maxillary 
bone. 

Attachment  of  Muscles. — To  six  ;  orbicularis  palpebrarum,  levator 
labii  superioris  proprius,  zygomaticus  minor  and  major,  masseter, 
and  temporal. 

Palate  Bones. — The  palate  bones  are  situated  at  the  posterior 
part  of  the  nares,  where  they  enter  into  the  formation  of  the  palate, 
the  side  of  the  nose,  and  the  posterior  part  of  the  floor  of  the  orbit ; 

hence  they  might  with  great  propriety  be  named  the  palato-naso- 

orbital  bones.     Each  bone  resembles  in  general  form  the  letter  L, 

and  is  divisible  into  a  horizontal  plate,  a  perpendicular  plate,  and  a 

pterygoid  process  or  tuberosity. 

The   horizontal  plate   is   quadrilateral ;    and 

presents    two    surfaces,   one    superior,  which  ^i?-  20.* 

enters  into   the   formation  of  the  floor  of  the 

nares,  the  other  inferior,  forming  the  posterior 

part  of  the  hard  palate.     The  superior  surface 

is  concave  and  rises  towards  the  middle  line, 

where  it  unites  with  its  fellow  of  the  opposite 

side  and  forms  a  crest,  which  articulates  with 

the  vomer.     The  inferior  surface  is  marked  by 

a  slight  transverse  ridge,  to  which  is  attached 

the  tendinous   expansion  of  the   tensor  palati 

muscle,  and  near  to  the  external  border  are  two 

openings,  the  posterior  palatine  foramina,  which 

transmit  the  posterior  palatine  nerves  and  artery.     The  posterior 

*  A  posterior  view  of  the  palate  bone  in  its  natural  position ;  it  is  slightly  turned  to 
one  side  to  obtain  a  sight  of  the  internal  surface  of  the  perpendicular  plate  (2.)  1.  The 
horizontal  plate  of  the  bone ;  its  upper  or  nasal  surface.     2.  The  perpendicular  plate  ; 

7 


50  PALATE  BONES. 

border  is  concave,  and  presents  at  its  inner  extremity  a  sharp  point, 
which  with  a  corresponding  point  in  the  opposite  bone  constitutes 
the  palate  spine  for  the  attachment  of  the  azygos  uvulse  muscle. 

The  perpendicular  plate  is  also  quadrilateral ;  and  presents  two 
surfaces,  one  internal  or  nasal,  forming  a  part  of  the  wall  of  the  nares ; 
the  other  external,  bounding  the  spheno-maxillary  fossa  and  antrum. 
The  internal  surface  is  marked  near  its  middle  by  a  horizontal 
ridge,  to  which  is  united  the  inferior  turbinated  bone.  The  slightly 
concave  surface  below  this  ridge  enters  into  the  formation  of  the 
inferior  meatus  of  the  nose,  and  that  above  the  ridge  of  the  middle 
and  superior  meatus.  The  external  surface,  extremely  irregular,  is 
rough  on  each  side  for  articulation  with  the  neighbouring  bones, 
and  smooth  in  the  middle  to  constitute  the  inner  boundary  of  the 
spheno-maxillary  fossa.  This  smooth  surface  terminates  inferiorly 
in  a  deep  groove,  which  being  completed  by  the  tuberosity  of  the 
superior  maxillary  bone  forms  the  posterior  palatine  canal. 

Near  the  upper  part  of  the  perpendicular  plate  is  a  large  opening, 
the  spheno-palatine  foramen,  which  transmits  the 
Fig.  21.*  spheno-palatine  nerves  and  artery,  and  serves  to 

divide  the  upper  extremity  of  the  bone  into  two 
portions,  an  anterior  or  orbital,  and  a  posterior 
or  sphenoidal  portion.     The  orbital  portion  pre- 
sents five  surfaces ;  three  articular,  and  two 
free ;  the  three  articular  are  the  anterior,  which 
looks  forward  and  articulates  with  the  superior 
maxillary  bone,  internal  with  the  ethmoid,  and 
posterior  with  the  sphenoid.    The  free  surfaces 
are  the  superior  or  orbital,  which  forms  the  pos- 
terior part  of  the  floor  of  the  orbit,  and  the  exter- 
nal, which  looks  into  the  spheno-maxillary  fossa. 
The  sphenoidal  portion,^  much  smaller  than 
the  orbital,  has  three  surfaces,  two  lateral  and  one  superior.     The 
external  lateral  surface  enters  into   the  formation  of  the  spheno- 

its  internal  or  nasal  surface.  3.  10,  11.  The  pterygoid  pi'occss  or  tuberosity.  4.  The 
broad  internal  border  of  the  horizontal  plate  which  articulates  with  the  similar  border 
of  the  opposite  bone.  5.  The  pointed  process,  which  with  a  similar  process  of  the 
opposite  bono  forms  the  palate  spine.  6.  The  horizontal  ridge  which  gives  attach- 
ment to  the  inferior  turbinated  bone ;  the  concavity  below  this  ridge  enters  into  the 
formation  of  the  inferior  meatus,  and  the  concavity  (2)  above  the  ridge  into  that  of  the 
middle  and  superior  meatus.  7.  The  spheno-palatine  foramen.  8.  Tlie  orbital  portion. 
10.  Tlie  middle  facet  of  the  tuberosity,  which  enters  into  the  formation  of  the  pterygoid 
fossa.  Tlie  ficets  11  and  .3  articulate  with  the  two  pterygoid  plates, — 11  with  the 
internal,  and  3  with  the  external. 

*  1'he  perpendicular  plate  of  the  palate  bone  seen  upon  its  external  or  spheno-maxil- 
lary surface.  1.  The  rough  surface  of  this  plate,  which  articulates  with  the  superior 
maxillary  bone.  2.  The  posterior  palatine  canal,  completed  by  the  tuberosity  of  the 
superior  maxillary  bone.  The  rough  surface  to  the  left  of  the  canal  (2)  articulates 
with  tiie  internal  pterygoid  plate.  3.  The  splicno-palatine  foramen.  4,  5,  G.  The 
orbital  portion  of  the  |)erpendicular  plate.  4.  The  spheno-maxillary  facet  of  this  por- 
tion ;  .0.  its  orbital  facet ;  G.  its  maxillary  facet,  to  articulate  with  the  superior  maxil- 
lary bone.  7.  The  splienoidal  portion  of  the  perpendicular  plate.  8.  The  pterygoid 
process  or  tuberosity  of  the  bone. 

t  Called  by  Horner,  the  pterygoid  apophysis. — G. 


INFERIOR  TURBINATED  BONE.  51 

mamillary  fossa ;  the  internal  lateral  forms  part  of  the  lateral  boun- 
dary of  the  nares ;  and  the  superior  surface  articulates  with  the 
under  part  of  the  body  of  the  sphenoid  bone. 

The  pterygoid  process  or  tuberosity  of  the  palate  bone  is  the  thick 
and  rough  process  which  stands  backwards  from  the  angle  of  union 
of  the  horizontal  with  the  perpendicular  portion  of  the  bone.  It  is 
received  into  the  angular  fissure,  which  exists  between  the  two 
plates  of  the  pterygoid  process  at  their  inferior  extremity,  and  pre- 
sents three  surfaces :  one  concave  and  smooth,  which  forms  part  of 
the  pterygoid  fossa ;  and  one  at  each  side  to  articulate  with  the 
pterygoid  plates.  The  anterior  face  of  this  process  articulates  with 
the  superior  maxillary  bone. 

Developement. — By  a  single  centre. 

Articulations. — With  six  bones;  two  of  the  cranium,  the  sphenoid 
and  ethmoid ;  and  four  of  the  face,  the  superior  maxillary,  inferior 
turbinated  bone,  vomer,  and  with  the  palate  bone  of  the  opposite 
side. 

Attachment  of  Muscles. — Ho  four  ;  the  tensor  palati,  azygos  uvulae, 
internal,  and  external  pterygoid. 

Inferior  Turbinated  Bones. — The  inferior  turbinated  or  spongy 
bone  is  a  thin  layer  of  loose  and  spongy  bone,  slightly  curled  upon 
itself,  and  projecting  inwards  from  the  inner  wall  of  the  nares.  It 
is  developed  from  a  single  centre,  and  gives  attachment  to  no 
muscles. 

Articulations. — 'With  four  bones;  the  ethmoid,  superior  maxillary, 
lachrymal,  and  palate. 

Vomer. — The  vomer  is  a  thin  and  quadrilateral  plate,  forming  a 
part  of  the  septum  of  the  nares.  Superiorly,  it  is  broad  and  expanded, 
and  forms  a  sheath  for  the  rostrum  of  the  sphenoid ;  inferiorly,  it  is 
thin,  and  received  into  a  groove,  formed  by  the  articulation  between 
the  palate  processes  of  the  superior  maxillary  and  palate  bone  of 
opposite  sides.  The  posterior  border  is  free,  and  divides  the  poste- 
rior nares ;  the  anterior  is  rough,  and  often  slit  into  two  layers,  to 
receive  the  sharp  edge  of  the  perpendicular  lamella  of  the  ethmoid 
bone,  and  of  the  cartilage  of  the  septum. 

The  vomer  frequently  presents  a  convexity  to  one  or  the  other 
side;  it  is  developed  by  a  single  centre,  and  has  no  muscles  attached 
to  it. 

Articulations. — With  six  bones ;  the  sphenoid,  ethmoid,  two  supe- 
rior maxillary,  and  two  palate  bones,  and  with  the  cartilage  of  the 
septum. 

Inferior  Maxillary  Bone. — The  lower  jaw  is  the  arch  of  bone 
which  contains  the  inferior  teeth ;  it  is  divisible  into  a  horizontal 
portion  or  body,  and  a  pei'pendicular  portion,  the  ramus,  at  each 
side. 

Upon  the  external  surface  of  the  body  of  the  bone,  at  the  middle 
line,  and  extending  from  between  the  two  first  incisor  teeth  to  the 
chin,  is  a  slight  ridge,  called  the  symphysis.  Immediately  external  to 
this  ridge  is  a  depression  which  gives  origin  to  the  depressor  labii 


52 


INFERIOR  MAXILLARY  BONE. 


inferioris  muscle;  and  corresponding  with  the  root  of  the  lateral 
incisor  tooth,  another  depression,  the  incisive  fossa,  for  the  levator 
labii  inferioris.  Further  outwards  is  an  oblique  opening,  the 
anterior  ?nental  foramen,  for  the  exit  of  the  inferior  dental  nerve 
and  artery,  and  below  this  foramen,  an  obhque  ridge  which  gives 
attachment  to  the  depressor  anguli  oris,  and  platysma  myoides. 
Near  the  posterior  part  of  this  surface  is  a  rough  impression  made 
by  the  masseter  muscle ;  and  immediately  in  front  of  this  impres- 
sion, a  groove  may  occasionally  be  seen  lor  the  facial  artery.  The 
projecting  tuberosity  at  the  posterior  extremity  of  the  lower  jaw,  at 
the  point  where  the  body  and  ramus  meet,  is  the  angle. 

Upon  the  internal  surface  of  the  body  of  the  bone  at  the  symphysis, 
are  two  small  pointed  tubercles ;  immediately  beneath  these,  two 
other  tubercles  less  marked  and  pointed,  beneath  them  a  ridge,  and 
beneath  the  ridge  a  rough  depression  of  some  size.  These  four 
points  give  attachment  from  above  downwards  to  the  genio-hyo- 
glossi,  genio-hyoidei,  part  of  the  mylo-hoidei  and  to  the  digastric 
muscles.  Running  outwards  into  the  body  of  the  bone  from  the 
above  ridge,  is  a  prominent  line,  the  mylo-hyoidean  ridge,  which 
gives  attachment  to  the  mylo-hyoideus  muscle,  and  by  its  extremity 
to  the  pterygo-maxillary  ligament  and  superior  constrictor  muscle. 
Immediately  above  the  ridge,  and  by  the  side  of  the  symphysis,  is  a 
smooth  concave  surface,  which  corresponds  with  the  sublingual 
gland;  and  below  the  ridge,  and  more  externally,  a  deeper  fossa  for 
the  submaxillary  gland. 

The  ramus  is  a  strong  square-shaped  process,  differing  in  direc- 
tion at  various  periods  of  life;  thus, 
in  the  foetus  and  infant,  it  is  almost 
parallel  with  the  body  ;  in  youth  it 
is  obhque,  and  gradually  increases 
in  the  vertical  direction  imtil  man- 
hood ;  in  old  age,  after  the  loss  of 
the  teeth,  it  again  declines  and 
assumes  the  oblique  direction. 
Upon  its  external  surface  it  is 
rough,  for  the.  attachment  of  the 
masseter  muscle  ;  and  at  the  junc- 
tion of  its  posterior  border  with  the 
body  of  the  bone,  is  a  rough  tube- 
rosity, the  angle  of  the  lower  jaw, 
which  gives  attachment  by  its  inner  margin  to  the  stylo-maxillary 
ligament. 

The  upper  extremity  of  the  ramus  presents  two  processes,  sepa- 
rated by  a  concave  sweep,  the  sigmoid  notch.     The  anterior  is  the 

*  The  lower  jaw.  1.  The  body.  2.  The  ramus.  .^.  The  symphysis.  4.  The 
fossa  for  the  depressor  labii  inferioris  muscle.  .5.  The  mental  foramen.  6.  The  external 
oblique  ridge.  7.  The  groove  for  the  facial  artery.  8.  The  angle.  9.  The  extremity 
of  the  mylo-hyoidcan  ridge.  10.  The  coronoid  process.  11.  The  condyle.  12.  The 
sigmoid  notcli.  13.  The  inferior  dental  foramen.  14.  The  mylo-hyoidean  groove. 
15.  The  alveolar  process,  i.  The  middle  and  lateral  incisor  tooth  of  one  side.  c.  The 
canine  tooth,    b.  The  two  bicuspides.    in.  The  three  molares. 


Fig.  22.* 


TABLE  OF  DEVELOPEMENTS,  ARTICULATIONS,  ETC. 


53 


coronoid  process ;  it  is  sharp  and  pointed,  and  gives  attachment  by- 
its  inner  surface  to  the  temporal  muscle.  The  anterior  border  of 
the  coronoid  process  is  grooved  at  its  lower  part  for  the  buccinator 
muscle.  The  posterior  process  is  the  condyle  of  the  low^er  jaw, 
which  is  flattened  from  before  backwards,  and  smooth  upon  its 
upper  surface,  to  articulate  with  the  inter-articular  fibro-cartilage. 
The  constriction  around  the  base  of  the  condyle  is  its  neck,  into 
which  is  inserted  the  external  pterygoid  muscle.  The  sigmoid 
notch  is  crossed  by  the  masseteric  artery  and  nerve. 

The  internal  surface  of  the  ramus  is  marked  near  its  centre  by  a 
large  oblique  foramen,  the  inferior  dental,*  for  the  inferior  dental 
artery  and  nerve.  Around  this  opening  is  a  rough  margin,  to  which 
is  attached  the  internal  lateral  ligament,  and  passing  downwards 
from  the  opening  a  narrow  groove  which  lodges  the  mylo-hyoidean 
nerve.  To  the  rough  surface  above,  and  in  front  of  the  inferior 
dental  foramen,  is  attached  the  temporal  muscle,  and  to  that  below 
it  the  internal  pterygoid.  The  internal  surface  of  the  neck  of  the 
condyle  gives  attachment  to  the  external  pterygoid  muscle ;  and  the 
angle  to  the  stylo-maxillary  ligament. 

Developement. — By  two  centres ;  one  for  each  lateral  half,  the  two 
sides  meeting  at  the  symphysis,  where  they  become  united. 

Articulations. — With  the  glenoid  fossas  of  the  two  temporal  bones, 
through  the  medium  of  a  fibro-cartilage. 

Attachment  of  Muscles. — To  fourteen  pairs;  by  the  external  sur- 
face commencing  at  the  symphysis,  and  proceeding  outwards, — 
levator  labii  inferioris,  depressor  labii  inferioris,  depressor  anguli 
oris,  platysma  myoides,  buccinator  and  masseter ;  by  the  internal 
surface  also  commencing  at  the  symphysis,  the  genio-hyo-glossus, 
genio-hyoideus,  mylo-hyoideus,  digastricus,  superior  constrictor, 
temporal,  external  pterygoid,  and  internal  pterygoid. 

Table  of  tJie  Points  of  Developement,  Articulations,  and  Attachment  of 
Muscles,  of  the  Bojies  of  the  Head. 


Occipital 
Parietal 

De 

velopement. 
4 

1 

Articulatior 
6 
5 

Attachment  of 
Ls.             muscles. 
13  pairs. 
1  muscle. 

Frontal 

. 

2 

12 

4  pairs. 

Temporal 

Sphenoid 

Ethmoid 

• 

5 

.       12 

3 

5 
12 
13       . 

14  muscles 
12  pairs, 
none. 

Nasal     . 

1 

4       . 

none. 

Superior  maxillary 

Lachrymal  . 

Malar    .       .       .       . 

6 

9 

4       . 
4 

9  muscles. 
1     ib. 
6     ib. 

Palate    . 

. 

6       . 

4     ib. 

Inferior  turbinated 

4 

none. 

Vomer  . 

. 

6 

none. 

Lower  jaw  . 

2 

2 

14  pairs. 

*  Called  also  posterior  mental  foramen. — G. 


54  SUTURES OSSA  TRiaUETRA. 


SUTURES. 


The  bones  of  the  cranium  and  face  are  connected  with  each 
other  by  means  of  sutures  (sutura,  a  seam),  of  whicli  there  are  four 
principal  varieties, — serrated,  squamous,  harmonia,  and  schindylesis. 

The  serrated  suture  is  formed  by  the  union  of  two  borders  pos- 
sessing serrated  edges,  as  in  the  coronal,  sagittal,  and  lambdoid 
sutures.  In  these  sutures  the  serrations  are  formed  almost  wholly 
by  the  external  table,  the  edges  of  the  internal  table  lying  nearly  in 
apposition. 

The  squamous  suture  (squama,  a  scale)  is  formed  by  the  over- 
lapping of  the  bevelled  edges  of  two  contiguous  bones,  as  in  the 
articulation  between  the  temporal  and  lower  border  of  the  parietal. 
In  this  suture  the  approximated  surfaces  are  roughened,  so  as  to 
adhere  mechanically  with  each  other. 

The  harmonia  suture  (agw,  to  adapt)  is  the  simple  apposition  of 
contiguous  surfaces,  the  surfaces  being  more  or  less  rough  and  re- 
tentive. This  suture  is  seen  in  the  connexion  between  the  superior 
maxillary  bones,  or  of  the  palate  processes  of  the  palate  bones  with 
each  other. 

The  schindylesis  suture  {d'xiv^xj'kridig,  a  fissure)  is  the  reception  of 
one  bone  into  a  sheath  or  fissure  of  another,  as  occurs  in  the  articu- 
lation of  the  sphenoid  with  the  vomer,  or  of  the  latter  with  the  per- 
pendicular lamella  of  the  ethmoid,  and  with  the  palate  processes  of 
the  superior  maxillary  and  palate  bones. 

The  serrated  suture  is  formed  by  the  interlocking  of  the  radia- 
ting fibres  along  the  edges  of  the  flat  bones  of  the  cranium  during 
growth.  When  this  process'  is  retarded  in  the  infant  by  over-dis- 
tention  of  the  head,  as  in  hydrocephalus,  and  sometimes  without 
any  such  apparent  cause,  distinct  ossific  centres  are  developed  in 
the  interval  between  the  edges;  and,  being  surrounded  by  the 
suture,  form  independent  pieces,  which  are  called  ossa  triquetra,  or 
ossa  Wormiana.  In  the  lambdoid  suture  there  is  generally  one  or 
more  of  these  bones ;  and,  in  a  beautiful  adult  hydrocephalic 
skeleton  in  the  possession  of  Mr.  Liston,  there  are  upwards  of  one 
hundred. 

The  coronal  suture  (fig.  23)  extends  transversely  across  the 
vertex  of  the  skull,  from  the  upper  part  of  the  greater  wing  of  the 
sphenoid  to  the  same  point  on  the  opposite  side ;  it  connects  the 
frontal  with  the  parietal  bones.  In  the  formation  of  this  suture  the 
edges  of  the  articulating  bones  are  bevelled,  so  that  the  parietal 
rest  upon  the  frontal  at  each  side,  and  in  the  middle  the  frontal  rests 
upon  the  parietal  bones,  so  as  to  afford  each  other  mutual  support 
in  the  consolidation  of  the  skull. 

The  sagittal  suture  (fig.  23)  extends  longitudinally  backwards 
along  the  vertex  of  the  skull,  from  the  middle  of  the  coronal  to  the 
apex  of  the  lambdoid  suture.  It  is  very  much  serrated,  and  serves 
to  unite  the  two  parietal  bones.    Sometimes  this  suture  is  continued 


SUPERIOR  REGIONS  OF  THE  SKULL.  55 

through  the  middle  of  the  frontal  bone  to  the  root  of  the  nose,  under 
the  name  of  the  frontal  suture. 

The  lambdoid  suture  is  named  from  some  resemblance  to  the 
Greek  letter  A,  consisting  of  two  branches,  which  diverge  at  an 
acute  angle  from  the  extremity  of  the  sagittal  suture.  This  suture 
connects  the  occipital  with  the  parietal  bones.  At  the  posterior  and 
inferior  angle  of  the  parietal  bones,  the  lambdoid  suture  is  con- 
tinued onwards  in  a  curved  direction  into  the  base  of  the  skull,  and 
serves  to  unite  the  occipital  bone  with  the  mastoid  portion  of  the 
temporal,  under  the  name  of  the  additamentum  sutures  lamhdoidalis. 
It  is  in  the  lambdoid  suture  that  the  ossa  triquetra  occiu*  most 
frequently. 

The  squamous  suture  (fig.  23)  unites  the  squamous  portion  of  the 
temporal  bone  with  the  greater  ala  of  the  sphenoid  and  with  the 
parietal,  overlapping  the  lower  border  of  the  latter.  The  portion 
of  the  suture  which  is  continued  backwards  from  the  squamous 
portion  of  the  bone  to  the  lambdoid  suture,  and  connects  the  mas- 
toid portion  with  the  posterior  inferior  angle  of  the  parietal  is  the 
additamentum  suturce  squamoscB. 

Across  the  upper  part  of  the  face  is  an  irregular  suture,  the  trans- 
verse, which  connects  the  frontal  bone  with  the  nasal,  superior  max- 
illary, lachrymal,  ethmoid,  sphenoid,  and  malar  bones.  The  other 
sutures  are  too  unimportant  to  deserve  particular  names  or  descrip- 
tion. 


REGIONS  OP  THE  SKULL. 

The  skull,  considered  as  a  whole,  is  divisible  into  four  regions, — 
a  superior  region,  or  vertex ;  a  lateral  region ;  an  inferior  region, 
or  base ;  and  an  anterior  region,  the  face. 

The  superior  region,  or  vertex  of  the  skull,  is  bounded  anteriorly 
by  the  frontal  eminences  ;  on  each  side  by  the  temporal  ridge  and 
parietal  eminences ;  and  behind  by  the  superior  curved  line  of 
the  occipital  bone  and  occipital  protuberance.  It  is  crossed  trans- 
versely by  the  coronal  suture,  and  marked  from  before  backwards 
by  the  sagittal,  which  terminates  posteriorly  in  the  lambdoid  suture. 
Near  the  posterior  extremity  of  the  region,  and  on  each  side  of  the 
sagittal  suture,  is  the  parietal  foramen.  Upon  the  inner,  or  cerebral 
surface  of  this  region,  is  a  shallow  groove,  extending  along  the 
middle  line  from  before  backwards,  for  the  superior  longitudinal 
sinus ;  on  either  side  of  this  groove  are  several  small  fossse  for  the 
Pacchionian  bodies,  and  still  further  outwards  numerous  ramified 
markings  for  lodging  the  branches  of  the  arteria  meningea  media. 

The  lateral  region  of  the  skull  is  divisible  into  three  portions  ; 
temporal,  mastoid,  and  zygomatic. 

The  temporal  portion,  or  temporal  fossa,  is  bounded  above  and 
behind  by  the  temporal  ridge,  in  front  by  the  external  angular  pro- 
cess of  the  frontal  bone  and  by  the  malar  bone,  and  below  by  the 
zygoma.     It  is  formed  by  part  of  the  frontal,  great  wing  of  the 


56 


BASE  OF  THE  SKULL. 


sphenoid,  parietal,  squamous  portion  of  the  temporal,  and  malar 
bone,  and  lodges  the  temporal  muscle. 


Fio'.  23* 


Fiff.  24.t 


The  mastoid  portion  is  rough,  for  the  attachment  of  muscles. 
Upon  its  posterior  part  is  the  mastoid  foramen,  and  below>  the  mas- 
toid process.  In  front  of  the  mastoid  process  is  the  external  audi- 
tory foramen,  surrounded  by  the  external  auditory  process ;  and 

*  A  front  view  of  the  skull.  1.  The  frontal  portion  of  the  frontal  bone.  The  2  im- 
mediately over  the  root  of  the  nose,  refers  to  the  nasal  tuberosity  ;  the  3  over  the  orbit, 
to  the  supra-orbital  rido^e.  4.  The  optic  foramen.  5.  Tlie  sphenoidal  fissure.  6.  The 
spheno-maxillary  fissure.  7.  The  lachrymal  fossa  in  the  lachrymal  bone,  the  com- 
mencement  of  the  nasal  duct.  The  fig-ures  4,  5,  6,  7,  are  within  the  orbit.  8.  The 
opening  of  the  anterior  nares,  divided  into  two  parts  by  the  vomer ;  the  number  is 
placed  upon  the  latter.  9.  The  infra-orbital  foramen.  ]0.  The  malar  bone.  11.  The 
symphysis  of  the  lower  jaw.  12.  The  mental  foramen.  13.  The  ramus  of  the  lower 
jaw.  14.  The  parietal  bone.  15.  The  coronal  suture.  16.  The  temporal  bone.  17. 
The  squamous  suture.  18.  The  upper  part  of  the  great  ala  of  the  sphenoid  bone.  19. 
The  commencement  of  the  temporal  ridge.  20.  The  zygoma  of  the  temporal  bone, 
assisting  to  form  the  zygomatic  arch.     21.  The  mastoid  process. 

t  The  cerebral  surface  of  the  base  of  the  skull.  1.  One  side  of  the  anterior  fossa ; 
the  number  is  placed  on  the  roof  of  the  orbit,  formed  by  the  orbital  plate  of  the  frontal 
bone.  2.  The  lesser  wing  of  the  splienoid.  3.  The  crista  galli.  4.  The  foramen 
csecum.  5.  The  cribriform  lamella  of  the  ethmoid.  6.  The  processus  olivaris.  7.  The 
foramen  opticum.  8.  The  anterior  clinoid  process.  9.  The  carotid  groove  upon  the 
side  of  the  sella  Turcica,  for  the  internal  carotid  artery  and  cavernous  sinus.  10,  11, 
12.  The  middle  fossa  of  the  base  of  the  skull.  10.  Marks  the  great  ala  of  the  sphe- 
noid. 11.  The  sfjuarnous  portion  of  the  temporal  bone.  12.  The  petrous  portion  of 
the  tcmjjoral.  13.  Tlic  sella  Turcica.  14.  The  basilar  portion  of  the  sphenoid  bone 
surmounted  by  the  posterior  clinoid  processes.  15.  The  foramen  rotundum.  16.  The 
foramen  ovale.  17.  The  foramen  spinosum ;  the  small  irregular  opening  between  17, 
and  12  is  the  hiatus  Fallopii.  18.  The  posterior  fossa  of  the  base  of  the  skull.  19, 
19.  The  groove  for  the  lateral  sinus.  20.  The  ridge  upon  the  occipital  bone,  which 
gives  attachment  to  the  falx  cerebelli.  21.  The  foramen  magnum.  22.  The  meatus 
auditoriiis  internus.     23.  The  jugular  foramen. 


BASE  OF  THE  SKULL.  57 

in  front  of  this  foramen  the  glenoid  cavity,  bounded  above  by  the 
middle  root  of  the  zygoma,  and  in  front  by  its  tubercle. 

The  zygomatic  'portion,  or  fossa,  is  the  irregular  cavity  below  the 
zygoma,  bounded  in  front  by  the  superior  maxillary  bone,  internally 
by  the  external  pterygoid  plate,  above  by  part  of  the  great  wing  of 
the  sphenoid  and  squamous  portion  of  the  temporal  bone,  and  by  the 
temporal  fossa,  and  externally  by  the  zygomatic  arch  and  ramus  of 
the  lower  jaw.  It  contains  the  external  pterygoid,  with  part  of  the 
temporal  and  internal  pterygoid  muscle,  and  the  internal  maxillary 
artery  and  inferior  maxillary  nerve,  with  their  branches.  At  the 
bottom  of  the  zygomatic  fossa  are  two  fissures,  the  spheno-maxillary 
and  the  pterygo-maxillary. 

The  spheno-maxillary  fissure  is  horizontal  in  direction,  opens  into 
the  orbit  and  is  situated  between  the  great  ala  of  the  sphenoid  and 
the  superior  maxillary  bone. 

The  pterygo-maxillary  fissure  is  vertical,  and  descends  at  right 
angles  from  the  extremity  of  the  preceding.  It  is  situated  between 
the  pterygoid  process  and  tuberosity  of  the  superior  maxillary  bone, 
and  transmits  the  internal  maxillary  artery.  At  the  angle  of  junc- 
tion of  these  two  fissures  is  a  small  cavity,  the  spheno-maxillary 
fossa,  bounded  by  the  sphenoid,  palate,  and  superior  maxillary  bones, 
in  which  are  seen  the  openings  of  five  foramina, — the  foramen  ro- 
tundum,  spheno-palatine,  ptery go-palatine,  posterior  palatine,  and 
Vidian.  It  lodges  Meckel's  ganglion  and  the  termination  of  the  in- 
ternal maxillary  artery. 

The  base  of  the  skull  presents  an  internal  or  cerebral,  and  an  ex- 
ternal or  basilar  surface. 

The  cerebral  surface  is  divisible  into  three  parts,  which  are  named 
the  anterior,  middle,  and  posterior  fossa  of  the  base  of  the  cranium. 
The  anterior  fossa  is  somewhat  convex  on  each  side,  where  it  cor- 
responds with  the  roofs  of  the  orbits ;  and  concave  in  the  middle, 
in  the  situation  of  the  ethmoid  bone,  and  the  anterior  part  of  the 
body  and  lesser  wings  of  the  sphenoid,  which  constitute  its  posterior 
boundary.  It  supports  the  anterior  lobes  of  the  cerebrum.  In  the 
middle  fine  of  this  fossa,  at  its  anterior  part,  is  the  crista  galli,  im- 
mediately in  front  of  this  process,  the  foramen  ccecum,  and  on  each 
side  the  cribriform  plate,  with  its  foramina,  for  the  transmission  of 
the  filaments  of  the  olfactory  and  nasal  branch  of  the  ophthalmic 
nerve.  Farther  back  in  the  middle  line  is  the  processus  olivaris,  and 
on  the  sides  of  this  process  the  optic  foramina,  anterior  clinoid  pro- 
cesses, and  vertical  grooves  for  the  internal  carotid  arteries. 

The  middle  fossa  of  the  base,  deeper  than  the  preceding,  is 
bounded  in  front  by  the  lesser  wing  of  the  sphenoid ;  behind,  by  the 
petrous  portion  of  the  temporal  bone  ;  and  is  divided  into  two  lateral 
parts  by  the  sella  Turcica.  It  is  formed  by  the  posterior  part  of 
the  body,  great  ala,  and  spinous  process  of  the  sphenoid,  and  by  the 
petrous  and  squamous  portion  of  the  temporal  bones.  In  the  centre 
of  this  fossa  is  the  sella  Turcica,  which  lodges  the  pituitary  gland, 
bounded  in  front  and  behind  bv  the  anterior  and  posterior  clinoid 

8* 


58  BASE  OF  THE  SKULL. 

processes.  On  each  side  of  the  sella  Turcica  is  the  carotid  groove 
for  the  internal  carotid  artery,  the  cavernous  plexus  of  nerves,  the 
cavernous  sinus,  and  the  orbital  nerves,  and  a  little  farther  outwards 
the  following  foramina  from  before  backwards,  s-phenoidal  fissure 
(foramen  lacerum  anterius)  for  the  transmission  of  the  third,  fourth, 
three  branches  of  the  ophthalmic  division  of  the  fifth,  and  the  sixth 
nerve,  and  ophthalmic  yein;  foramen  rotundum,  for  the  superior  max- 
illary nerve  ;  foramen  ovale,  for  the  inferior  maxillary  nerve,  arteria 
menincrea  parva,  and  nervus  petrosus  superficialis  minor  ; — foraynen 
spinosum,  for  the  arteria  meningea  magna  ;  foramen  lacerum  basis 
cranii,  which  gives  passage  to  the  internal  carotid  artery,  carotid 
plexus,  and  petrosal  branch  of  the  Vidian  nerve.  On  the  anterior 
surface  of  the  petrous  portion  of  the  temporal  bone  is  a  groove, 
leading  to  a  fissured  opening,  the  hiatus  Fallopii,  for  the  petrosal 
branch  of  the  Vidian  nerve  ;  and  immediately  beneath  this  a  smaller 
foramen,  for  the  nervus  petrosus  superficialis  minor.  Towards 
the  apex  of  this  portion  of  bone  is  the  notch  for  the  fifth  nerve,  and 
below  it  a  slight  depression  for  the  Casserian  ganglion.  Farther 
outwards  is  the  eminence  which  marks  the  position  of  the  perpen- 
dicular semicircular  canal.  Proceeding  from  the  foramen  spinosum 
are  two  grooves  which  mark  the  course  of  the  trunks  of  the  arteria 
menino-ea  media.  The  whole  fossa  lodges  the  middle  lobes  of  the 
cerebrum. 

The  posterior  fossa,  larger  than  the  other  two,  is  formed  by  the 
occipital  bone,  by  the  petrous  and  mastoid  portion  of  the  temporals, 
and  by  a  small  part  of  the  sphenoid  and  parietals.  It  is  bounded  in 
front  by  the  upper  border  of  the  petrous  portion,  and  by  the  poste- 
rior clinoid  processes,  and  along  its  posterior  circumference  by  the 
groove  for  the  lateral  sinuses,  and  gives  support  to  the  pons  Varolii, 
medulla  oblongata,  and  cerebellum.  In  the  centre  of  this  fossa  is 
the  foramen  magnum  bounded  on  each  side  by  a  rough  tubercle, 
which  gives  attachment  to  the  odontoid  ligament,  and  by  the  anterior 
condyloid  foramen.  In  front  of  the  foramen  magnum  is  the  con- 
cave surface  which  supports  the  medulla  oblongata  and  pons  Va- 
rolii, and  on  each  side  the  following  foramina  from  before  back- 
wards. The  internal  auditory  foramen,  for  the  auditory  and  facial 
nerve  and  auditory  artery ;  behind,  and  external  to  this  is  a  small 
foramen  leading  into  the  aquceductus  vesiibuli ;  and  below  it,  partly 
concealed  bv  the  edge  of  the  petrous  bone,  the  aquceductus  cochlea  ; 
next,  a  long  fissure,  the  foramen  lacerum  poslerius,  or  jugular  fora- 
men, giving  passage  to  the  commencement  of  the  internal  jugular 
vein  and  the  eighth  pair  of  nerves.  Converging  towards  this  fora- 
men from  behind  is  the  deep  grove  for  the  lateral  sinus,  and  from 
the  front  the  groove  for  the  inferior  petrosal  sinus. 

Behind  the  foramen  magnum  is  a  longitudinal  ridge,  which  gives 
attachment  to  the  falx  cerebelli,  and  divides  the  two  inferior  fossae  of 
the  occipital  bone ;  and  above  the  ridge  is  the  elevation  correspond- 
ing with  the  tubercle  of  the  occipital  bone  and  the  transverse  groove 
lodging  the  lateral  sinus. 


BASE  OF  THE  SKULL. 


59 


Fig.  25.* 


The  external  surface  of  the  base  of  the  skull  is  extremely  irregu- 
lar. From  before  backwards  it  is  formed  by  the  palate  processes 
of  the  superior  maxillary  and  pa- 
late bones ;  the  vomer ;  the  ptery- 
goid, spinous  processes,  and  part 
of  the  body  of  the  sphenoid ;  under 
surface  of  the  squamous  portion, 
and  mastoid  portion  of  the  tem- 
porals ;  and  by  the  occipital  bone. 
The  palate  processes  of  the  supe- 
rior maxillary  and  palate  bones 
constitute  the  hard  palate,  which 
is  raised  above  the  level  of  the 
rest  of  the  base,  and  is  surrounded 
by  the  alveolar  processes  contain- 
ing the  teeth  of  the  upper  jaw.  At 
the  anterior  extremity  of  the  hard 
palate,  and  directly  behind  the 
front  incisor  teeth,  is  the  incisive 
foramen,  the  termination  of  the  naso- 
palatine canal,  which  contains  the 
naso-palatine  ganglion,  and  trans- 
mits the  anterior  palatine  nerves.  At 
the  posterior  angles  of  the  palate  are  the  posterior  'palatine  foramina, 
for  the  posterior  palatine  nerves  and  arteries.  Passing  inwards  from 
these  foramina  are  the  transverse  ridges  to  which  are  attached  the  ex- 
pansions of  the  tensor  palati  muscles,  and  at  the  middle  hne  of  the 
posterior  border  the  palate  spine  which  gives  origin  to  the  azygos 
uvulae.  The  hard  palate  is  marked  by  a  crucial  suture,  which  distin- 
guishes the  four  processes  of  which  it  is  composed.  Behind,  and  above 
the  hard  palate,  are  the  posterior  nares,  separated  by  the  vomer,  and 
bounded  on  each  side  by  the  pterygoid  processes.  At  the  base  of  the 
vomer,  and  partly  formed  by  its  expansion,  are  the  pterygo-palatine 
canals.  The  internal  pterygoid  plate  is  long  and  narrow,  terminated 
at  its  apex  by  the  hamular  process,  and  at  its  base  by  the  scaphoid 
fossa.  The  external  plate  is  broad,  and  the  space  between  the  two  is 
the  pterygoid  fossa,  which  contains  part  of  the  internal  pterygoid 
muscle  and  the  tensor  palati.     Externally  to  the  external  pterygoid 

*  The  external  or  basilar  surface  of  the  base  of  the  skull.  1,  1.  The  hard  palate. 
The  figures  are  placed  upon  the  palate  processes  of  the  superior  maxillary  bones.  2. 
The  incisive,  or  anterior  palatine  foramen.  3.  The  palate  process  of  the  palate  bone. 
The  large  opening  near  the  figure  is  the  posterior  palatine  foramen.  4.  The  palate 
spine;  the  curved  line  upon  vs^hich  the  number  rests,  is  the  transverse  ridge.  5.  The 
vomer,  dividing  the  openings  of  the  posterior  nares.  6.  The  internal  pterygoid  plate. 
7.  The  scaphoid  fossa.  8.  The  external  pterygoid  plate.  The  interval  between  6  and  8, 
(left  side  of  the  figure,)  is  the  pterygoid  fossa.  9.  The  zygomatic  fossa.  10.  The 
basilar  process  of  the  occipital  bone.  11.  The  foramen  magnum.  12.  The  foramen 
ovale.  13.  The  foramen  spinosum.  14.  The  glenoid  fossa.  15.  The  meatus  audi- 
torius  externus.  16.  The  foramen  lacerum  basis  cranii.  17.  The  carotid  foramen  of 
the  left  side.  18.  The  foramen  lacerum  posterius,  or  jugular  foramen.  19.  The 
styloid  process.  20.  The  stylo-mastoid  foramen.  21.  The  mastoid  process.  22.  One 
of  the  condyles  of  the  occipital  bone.     23.  The  posterior  condyloid  foramen. 


60  BASE  OF  THE  SKULL. 

is  the  zygomatic  fossa.  Behind  the  nasal  fossse,  in  the  middle  line, 
is  the  under  surface  of  the  body  of  the  sphenoid,  and  the  basilar 
process  of  the  occipital  bone,  and  still  further  back,  the  foramen 
magnum.  At  the  base  of  the  external  pterygoid  plate,  on  each 
side,  is  the  foramen  ovale,  and  behind  this  the  foramen  spinosum, 
with  the  prominent  spine  which  gives  attachment  to  the  internal 
lateral  ligament  of  the  lower  jaw  and  the  laxator  tympani  muscle. 
Running  outwards  from  the  apex  of  the  spinous  process  of  the 
sphenoid  bone,  is  the  fissura  Glaseri,  which  crosses  the  glenoid 
fossa  transversely,  and  divides  it  into  an  anterior  smooth  surface, 
bounded  by  the  eminentia  articularis,  for  the  condyle  of  the  lower 
jaw,  and  a  posterior  rough  surface  for  a  part  of  the  parotid  gland. 
Behind  the  foramen  ovale  and  spinosum,  is  the  irregular  fissure 
between  the  spinous  process  of  the  sphenoid  bone  and  the  petrous 
portion  of  the  temporal,  the  foramen  lacerum  basis  cranii,  which 
lodges  the  internal  carotid  artery  and  Eustachian  tube,  and  in 
which  the  carotid  branch  of  the  Vidian  nerve  joins  the  carotid 
plexus.  Following  the  direction  of  this  fissure  outwards  is  the 
foramen  for  the  Eustachian  tube,  and  that  for  the  tensor  tympani 
muscle,  separated  from  each  other  by  the  processus  cochleariformis. 
Behind  the  fissure  is  the  pointed  process  of  the  petrous  bone  which 
gives  origin  to  the  levator  palati  muscle,  and,  externally  to  this  pro- 
cess, the  carotid  foramen  for  the  transmission  of  the  internal  carotid 
artery  and  the  ascending  branch  of  the  superior  cervical  ganglion 
of  the  sympathetic ;  and  behind  the  carotid  foramen,  the  foramen 
lacerum  posterius  and  jugular  fossa.  Externally,  and  somewhat  in 
front  of  the  latter,  is  the  styloid  process,  and  at  its  base  the  vaginal 
process.  Behind  and  at  the  root  of  the  styloid  process  is  the  stylo- 
mastoid foramen,  for  the  facial  nerve  and  stylo-mastoid  artery,  and 
further  outwards  the  mastoid  process.  Upon  the  inner  side  of  the 
root  of  the  mastoid  process  is  the  digastric  fossa ;  and  a  little  far- 
ther internally,  the  occipital  groove.  On  either  side  of  the  fora- 
men magnum,  and  near  to  its  anterior  circumference,  are  the  con- 
dyles of  the  occipital  bone.  In  front  of  each  condyle,  and  piercing 
its  base,  is  the  anterior  condyloid  foramen,  and  directly  behind  the 
condyle  the  irregular  fossa  in  which  the  posterior  condyloid  foramen 
is  situated.  Behind  the  foramen  magnum  are  the  two  curved  fines 
of  the  occipital  bone,  the  spine,  and  protuberance,  with  the  rough 
surfaces  for  the  attachment  of  muscles. 

The  Face  is  somewhat  oval  in  contour,  irregular  in  surface,  and 
excavated  for  the  reception  of  two  principal  organs  of  sense, — the 
eye  and  the  nose.  It  is  formed  by  part  of  the  frontal  bone  and  by 
the  bones  of  the  face.  Superiorly  it  is  bounded  by  the  frontal 
eminences ;  beneath  these  are  the  superciliary  ridges,  converging 
towards  the  nasal  tuberosity ;  beneath  the  superciliary  ridges  are 
the  supra-orbital  ridges,  terminating  externally  in  the  external 
border  of  the  orbit,  and  internally  in  the  internal  border,  and  pre- 
senting towards  their  inner  third  the  supra-orbital  notch,  for  the 
supra-orbital  nerve  and  artery.  Beneath  the  supra-orbital  ridges 
are  the  openings  of  the  orbits.     Between  the  orbits  is  the  bridge  of 


THE  FACE.  61 

tlie  nose,  overarching  the  anterior  nares  ;  and  on  each  side  of  this 
opening  the  canine  fossa  of  the  superior  maxillary  bone  and  the 
infra-orbital  foramen,  and  still  farther  outwards  the  prominence  of 
the  malar  bone ;  at  the  lower  margin  of  the  anterior  nares  is  the 
nasal  spine,  and  beneath  this  the  superior  alveolar  arch  containing 
the  teeth  of  the  upper  jaw.  Forming  the  lower  boundary  of  the 
face  is  the  lower  jaw,  containing  in  its  alveolar  process  the  lower 
teeth,  and  projecting  inferiorly  to  form  the  chin ;  on  either  side  of 
the  chin  is  the  mental  foramen.  If  a  perpendicular  line  be  drawn 
from  the  inner  third  of  the  supra-orbital  ridge  to  the  inner  third  of 
the  body  of  the  lower  jaw,  it  will  be  found  to  intersect  three  open- 
ings ; — the  supra-orbital,  infra-orbital,  and  mental,  each  giving 
passage  to  one  of  the  facial  branches  of  the  fifth  nerve. 

ORBITS. 

The  orbits  are  two  quadrilateral  hollow  cones,  situated  in  the 
upper  part  of  the  face,  and  intended  for  the  reception  of  the  eye- 
balls, with  their  muscles,  vessels,  and  nerves,  and  the  lachrymal 
glands.  The  central  axis  of  each  orbit  is  directed  outwards,  so 
that  the  axes  of  the  two  continued  into  the  skull  through  the  optic 
foramina,  would  intersect  over  the  middle  of  the  sella  Turcica.* 
The  superior  boundary  of  the  orbit  is  formed  by  the  orbital  plate  of 
the  frontal  bone,  and  by  part  of  the  lesser  wing  of  the  sphenoid ; 
the  inferior,  by  part  of  the  malar  bone  and  by  the  orbital  processes 
of  the  superior  maxillary  and  palate  bone;  the  internal  by  the 
lachrymal  bone,  the  os  planum  of  the  ethmoid  and  part  of  the 
body  of  the  sphenoid ;  and  the  external,  by  the  orbital  process  of 
the  malar  bone  and  the  great  ala  of  the  sphenoid ;  these  may  be 
expressed  more  clearly  in  a  tabular  form : — 

Frontal. 
Sphenoid  (lesser  wing). 

Malar.  Lachrymal. 

Sphenoid  (greater  wing).  Orbit.  Ethmoid  (os  planmn). 

Sphenoid  (body). 

Malar. 

Superior  maxillary. 

Palate. 

There  are  nine  openings  communicating  with  the  orbit: — the 
optic,  for  the  admission  of  the  optic  nerve  and  ophthalmic  artery ; 
the  sphenoidal  fissure,  for  the  transmission  of  the  third,  fourth,  the 
three  branches  of  the  ophthalmic  division  of  the  fifth,  and  the  sixth 
nerve,  and  the  ophthalmic  vein ;  the  spheno-maxillary  fissure,  for  the 
passage  of  the  superior  maxillary  nerve  and  artery  to  the  openino- 
of  entrance  of  the  infra-orbital  canal;  temporo-malar  fm^amina — 
two  or  three  small  openings  in  the  orbital  process  of  the  malar 

*  The  axes  of  the  orbits  form  an  angle  of  90°  with  each  other.     G. 


62 


NASAL  POSS^, 


bone,  for  the  passage  of  filaments  of  the  orbital  branch  of  the  supe- 
rior maxillary  nerve ;  anterior  and  posteyior  ethmoidal  foramina  in 
the  suture  between  the  os  planum  and  frontal  bone,  the  former 
transmitting  the  nasal  nerve  and  anterior  ethmoidal  artery  and 
the  latter  the  posterior  ethmoidal  artery  and  vein ;  the  opening  of 
the  nasal  duct;  and  the  swpra-orhiial  notch  or  foramen,  for  the 
supra-orbital  nerve  and  artery. 


NASAL  FOSS^. 

The  nasal  fossae  are  two  irregular  cavities,  situated  in  the  middle 
of  the  face,  and  extending  from  before  backwards.  They  are 
bounded  above  by  the  nasal  bones,  ethmoid,  and  sphenoid ;  below 
by  the  palate  processes  of  the  superior  maxillary  palate  bones ; 
externally  by  the  superior  maxillary,  lachrymal,  inferior  turbinated, 
ethmoid,  palate,  and  internal  pterygoid  plate  of  the  sphenoid  ;  and 
the  two  fossae  are  separated  by  the  vomer  and  the  perpendicular 
lamella  of  the  ethmoid.  These  may  be  more  clearly  expressed  in 
a  tabular  form  : — 

Nasal  bones. 
Ethmoid. 
Sphenoid. 


o-Ph 


(r>      ^ 


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rt 

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(^       13 

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rt          -is 

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axill 
mal. 
rbina 

bS 

Nasal  fossa. 

^ 

Nasal  fossa. 

S  t^B. 

Si        iH 

aj 

fc,  .c   . 

g.2 

d 

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3 

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3         fl 

Vu 

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tC        M 

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IPh  &. 


Palate  processes  of  superior  maxillary, 
Palate  processes  of  palate  bone. 

Each  nasal  fossa  is  divided  into  three  irregular  longitudinal  pas- 
sages, or  meatuses  by  three  processes  of  bone,  which  project  from 
its  outer  wall, — the  superior,  middle,  and  inferior  turbinated  bones  ; 
the  superior  and  middle  turbinated  bones  being  processes  of  the 
ethmoid,  and  the  inferior  a  distinct  bone  of  the  face.  The  superior 
meatus  occupies  the  superior  and  posterior  part  of  each  fossa ;  it  is 
situated  between  the  superior  and  middle  turbinated  bones,  and  has 
opening  into  it  three  foramina,  viz.  the  opening  of  the  posterior 
ethmoid  cells,  the  opening  of  the  sphenoid  cells,  and  the  spheno- 
palatine foramen.  The  middle  meatus  is  the  space  between  the 
middle  and  inferior  turbinated  bones  ;  it  also  presents  three  foramina, 
— the  opening  of  the  frontal  sinuses,  of  the  anterior  ethmoid  cells, 
and  of  the  antrum.  The  largest  of  the  three  passages  is  the  in- 
ferior meatus,  which  is  the  space  between  the  inferior  turbinated 
bone  and  the  floor  of  the  fossa;  in  it  there  are  two  foramina, — the 


TEETH-*— DIVISIONS.  63 

termination  of  the  nasal  duct,  and  the  opening  of  the  naso-palatine 
canal.  The  nasal  fossae  commence  upon  the  face  by  a  large  irregu- 
lar opening, — the  anterior  nare§, — and  terminate  posteriorly  in  the 
two  posterior  nares. 

TEETH. 

Man  is  provided  with  two  successions  of  teeth ;  the  first  are  the 
teeth  of  childhood,  they  are  called  temporary  or  deciduous ;  the 
second  continue  until  old  age,  and  are  named  permanent. 

The  permanent  teeth  are  thirty-two  in  number,  sixteen  in  each 
jaw ;  they  are  divisible  into  four  classes, — incisors,  of  which  there 
are  four  in  each  jaw,  two  central  and  two  lateral;  canine,  two 
above  and  two  below ;  bicuspid,  four  above  and  four  below ;  and 
molars,  six  above  and  six  below. 

The  temporary  teeth,  are  twenty  in  number ;  eight  incisors,  four 
canine,  and  eight  molars.  The  temporary  molars  have  four 
tubercles,  and  are  succeeded  by  the  permanent  bicuspides,  which 
have  only  two  tubercles. 

Each  tooth  is  divisible  into  a  crown,  which  is  the  part  apparent 
above  the  gum ;  a  constricted  portion  around  the  base  of  the 
crown,  the  neck ;  and  a  root  or  fang,  which  is  contained  within  the 
alveolus.  The  root  is  invested  by  periosteum,  which  lines  the 
alveolus,  and  is  then  reflected  upon  the  root  of  the  tooth  as  far  as 
its  neck. 

The  incisor  teeth  (cutting  teeth)  are  named  from  presenting  a 
sharp  and  cutting  edge,  formed  at  the  expense  of  the  posterior  sur- 
face. The  crown  is  flattened  from  before  backwards,  being  some- 
what convex  in  front  and  concave  behind ;  the  neck  is  considerably 
constricted,  and  the  root  compressed  from  side  to  side ;  at  its  apex 
is  a  small  opening  for  the  passage  of  the  nerve  and  artery  of  the 
tooth. 

The  canine  teeth  (cuspidati)  follow  the  incisors  in  order  from 
before  backwards ;  two  are  situated  in  the  upper  jaw,  one  on  each 
side,  and  two  in  the  lower.  The  crown  is  larger  than  that  of  the 
incisors,  convex  before,  and  concave  behind,  and  tapering  to  a 
blunted  point.  The  root  is  longer  than  that  of  all  the  other  teeth, 
compressed  at  each  side,  and  marked  by  a  slight  groove. 

The  bicuspid  teeth  (small  molars),  two  on  each  side  in  each  jaw, 
follow  the  canine,  and  are  intermediate  in  size  between  them  and 
the  molars.  The  crown  is  compressed  from  before  backwards, 
and  surmounted  by  two  tubercles,  one  internal,  the  other  external ; 
the  neck  is  oval ;  the  root  compressed,  and  marked  on  each  side 
by  a  deep  groove,  and  bifid  near  its  apex.  The  teeth  of  the  upper 
jaw  have  a  greater  tendency  to  the  division  of  their  roots  than 
those  of  the  lower,  and  the  posterior  than  the  anterior  pair. 

The  molar  teeth  (grinders,)  three  on  each  side  in  each  jaw,  are 
the  largest  of  the  permanent  set.  The  crown  is  quadrilateral,  and 
surmounted  by  four  tubercles,  the  neck  large  and  round,  and  the 


64  STRUCTURE  OF    TEETH. 

root  divided  into  several  fangs.  In  the  upper  jaw  the  first  and 
second  molar  teeth  have  three  roots,  sometimes  four,  which  are 
more  or  less  widely  separated  from  each  other,  two  of  the  roots 
being  external,  the  other  internal.  In  the  lower  there  are  but  two 
roots,  which  are  anterior  and  posterior;  they  are  flattened  from 
behind  forwards,  and  grooved  so  as  to  mark  a  tendency  to  division. 
The  third  molars,  or  dentes  sapientise,  are  smaller  than  the  other 
two ;  they  present  three  tubercles  on  the  surface  of  the  crown ;  and 
the  root  is  single  and  grooved,  appearing  to  be  made  up  of  four 
or  five  fangs  compressed  together,  or  partially  divided.  In  the 
lower  jaw  the  fangs  are  frequently  separated  to  some  distance  from 
each  other,  and  much  curved,  so  as  to  offer  considerable  resistance 
in  the  operation  of  extraction.* 

Structure.^ — The  base  of  the  crown  of  each  tooth  is  hollowed  into 
a  small  cavity,  which  is  continuous  with  a  canal  passing  through  the 
middle  of  each  fang.  The  cavity  and  canal,  or  canals,  constitute 
cavitas  pulpse,  and  contain  a  soft  and  secreting  vascular  organ, — 
the  jiulp,  which  receives  its  supply  of  vessels  and  nerves  through 
the  small  opening  at  the  apex  of  each  root. 

The  tooth  is  composed  of  three  distinct  structures ;  the  ivory  or 
tooth-bone,  enamel,  and  a  cortical  substance  or  cementum.  The 
ivory  consists  of  microscopic  undulating  and  branching  tubuli, 
which  open  by  their  larger  extremities  upon  the  walls  of  the  cavitas 
pulpse  and  radiate  towards  the  surface  of  the  ivory,  where  they  ter-^ 
minate  in  ramifications  of  infinite  minuteness.  These  tubuli  have 
distinct  walls,  are  separated  from  each  other  by  intervals  equal  in 
breadth  to  the  diameter  of  two  or  three  tubes,  and  composed  of 
dense  dental  substance,  and  they  contain  within  their  cylinders  a 
calcareous  substance  disposed  in  irregular  masses. J  As  the  growth 
of  the  tooth  takes  place  from  the  surface  towards  the  centre,  the 
most  minute  ramifications  are  first  formed,  and  the  trunks  of  the 
tubuli  are  the  last  deposited. 

The  enamel  forms  a  crust  over  the  whole  exposed  surface  of  the 
crown  of  the  tooth  to  the  commencement  of  its  root ;  it  is  thickest 
over  the  upper  part  of  the  crown,  and  becomes  gradually  thinner  as 
it  approaches  the  neck.  It  is  composed  of  minute  hexagonal  crys- 
talline fibres,  resting  by  one  extremity  against  the  surface  of  the 
ivory,  and  constituting  by  the  other  the  free  surface  of  the  crown. 
The  enamel  is  separated  from  the  ivory  by  a  thin  layer  of  mem- 
brane, continuous  with  a  thin  organic  sheath  which  encloses  each 
enamel  fibre,  and  marks  it  by  means  of  transverse  lines  into  irre- 
gular divisions.    Mr.  Nasmyth  is  of  opinion,  that  the  enamel  is  in- 

*  See  a  valuable  little  praetical  work,  "  On  the  Structure,  Economy,  and  Pathology 
of  the  Teeth,"  by  Mr.  Lintott. 

t  The  structure  of  the  teeth  was  discovered  by  Purkinje  and  Retzius,  and  has  been 
farther  prosecuted  in  this  country  by  Mr.  Nasmyth,  to  whose  beautiful  work,  "  Re- 
searches on  the  Developcment,  Structure  and  Diseases  of  the  Teeth,"  I  must  refer 
those  who  may  feel  interested  in  this  important  subject. 

t  The  disintegrated  condition  of  the  calcareous  substance  is  probably  the  effect  of 
desiccation ;  it  is  very  remarkable  in  decayed  teeth. 


DEVEL0PE3IENT  OF  TEETH.  65 

vested  by  a  thin  layer  of  membrane,  which  is  continued  over  the 
root,  and  is  reflected  through  the  opening  in  the  apex  of  the  fang 
into  the  cavitas  pulpse,  whicli  it  lines  throughout.  This  membrane 
is  considered  by  Mr.  Nasmyth  to  be  the  ^'■persistent  dental  capsule." 

The  cortical  substance,  or  cementum,  forms  a  thin  coating  over 
the  root  of  the  tooth,  from  the  termination  of  the  enamel  to  the 
opening  of  the  apex  of  the  fang.  In  structure  it  consists  of  true 
bone,  characterized  by  the  existence  of  numerous  calcigerous 
cells  and  tubuli.  The  cementum  increases  in  thickness  with  the 
advance  of  age,  and  gives  rise  to  those  exostosed  appearances 
occasionally  seen  in  the  teeth  of  very  old  persons,  or  in  those  who 
have  taken  much  mercury.  In  old  age  the  cavitas  pulpse  is  often 
found  filled  up  and  obliterated  by  osseous  substance  analogous  to 
the  cementum. 

Developement. — The  developement  of  the  teeth  in  the  human  sub- 
ject has  been  most  successfully  investigated  by  our  countryman, 
Mr.  Goodsir,  to  whose  interesting  researches  I  am  indebted  for  the 
following  narrative  : — * 

The  inquiries  of  Mr.  Goodsir  commenced  as  early  as  the  sixth 
week  after  conception,  in  an  embryo,  which  measured  seven  lines 
and  a  half  in  length  and  weighed  fifteen  grains.  At  this  early 
period  each  jaw  presents  two  semicircular  folds  around  its  circum- 
ference ;  the  most  external  is  the  true  lip ;  the  internal,  the  rudiment 
of  the  palate ;  and  between  these  is  a  deep  groove,  Hned  by  the 
common  mucous  membrane  of  the  mouth.  A  little  later  a  ridge 
is  developed  from  the  floor  of  this  groove  in  a  direction  from  behind 
forwards,  this  is  the  rudiment  of  the  external  alveolus ;  and  the 
arrangement  of  the  appearances  from  without  inwards  at  this 
period  is  the  following : — Most  externally,  and  forming  the  boun- 
dary of  the  mouth,  is  the  lip  ;  next  we  find  a  deep  groove,  which 
separates  the  lip  from  the  future  jaw ;  then  comes  the  external 
alveolar  ridge  ;  fourthly,  another  groove,  in  which  the  germs  of 
the  teeth  are  developed,  the  primitive  dental  groove ;  fifthly,  a  rudi- 
ment of  the  internal  alveolar  ridge  ;  and  sixthly,  the  rudiment  of 
the  future  palate  bounding  the  whole  internally.  At  the  seventh 
week  the  germ  of  the  first  deciduous  molar  of  the  upper  jaw  has 
made  its  appearance,  in  the  form  of  a  "  simple,  free,  granular 
papilla"  of  the  mucous  membrane,  projecting  from  the  floor  of 
the  primitive  dental  groove  ;  at  the  eighth  week,  the  papilla  of  the 
canine  tooth  is  developed  ;  at  the  ninth  week  the  papillae  of  the  four 
incisors  (the  middle  preceding  the  lateral)  appear ;  and  at  the  tenth 
week,  the  papilla  of  the  second  molar  is  seen  behind  the  anterior 
molar  in  the  primitive  dental  groove.  So  that  at  this  early  period, 
the  tenth  week,  the  papillas  or  germs  of  the  whole  of  the  ten  deci- 
duous teeth  of  the  upper  jaw  are  quite  distinct.  Those  of  the  lower 
jaw  are  a  little  more  tardy  ;  the  papilla  of  the  first  molar  is  merely 

*  "  On  the  Origin  and  Developement  of  the  Pulps  and  Sacs  of  the  Human  Teetli," 
by  John  Goodsir,  jun.,  in  the  Edinburgh  Medical  and  Surgical  Joyrnal,  January  1839. 

9 


66  DEVELOPEMENT  OF  TEETH. 

a  slight  bulging  at  the  seventh  week,  and  the  tenth  papilla  is  not 
apparent  until  the  eleventh  week. 

From  about  the  eighth  week  the  primitive  dental  groove  becomes 
contracted  before  and  behind  the  first  deciduous  molar,  and  laminse 
of  the  mucous  membrane  are  developed  around  the  other  papillae, 
which  increase  in  growth  and  enclose  the  papilloe  in  follicles  with 
open  mouths.  At  the  tenth  week  the  follicle  of  the  first  molar  is 
completed,  then  that  of  the  canine ;  during  the  eleventh  and  twelfth 
weeks  the  follicles  of  the  incisors  succeed,  and  at  the  thirteenth 
week  the  follicle  of  the  posterior  deciduous  molar. 

During  the  thirteenth  week  the  papillae  undergo  an  alteration  of 
form,  and  assume  the  shape  of  the  teeth  they  are  intended  to  repre- 
sent. And  at  the  same  time  small  membranous  processes  are  de- 
veloped from  the  mouths  of  the  follicles ;  these  processes  are  intended 
to  serve  the  purpose  of  opercula  to  the  follicles,  and  they  correspond 
in  shape  with  the  form  of  the  crowns  of  their  appertaining  teeth. 
To  the  follicles  of  the  incisor  teeth  there  are  two  opercula ;  to  the 
canine,  three;  and  to  the  molars  a  number  relative  to  the  number 
of  their  tubercles,  either  four  or  five.  During  the  fourteenth  and 
fifteenth  weeks  the  opercula  have  completely  closed  the  folhcles,  so 
as  to  convert  them  into  dental  sacs,  and  at  the  same  time  the  papillse 
have  become  -pulfs. 

The  deep  portion  of  the  primitive  dental  groove,  viz.  that  which 
contains  the  dental  sacs  of  the  deciduous  teeth,  being  thus  closed  in, 
the  remaining  portion,  that  which  is  nearer  the  surface  of  the  gum, 
is  still  left  open,  and  to  this  Mr.  Goodsir  has  given  the  title  of 
secondary  dental  groove ;  as  it  serves  for  the  developement  of  all  the 
permanent  teeth,  with  the  exception  of  the  anterior  molars.  During 
the  fourteenth  and  fifteenth  weeks  small  lunated  inflections  of  the 
mucous  membrane  are  formed,  immediately  to  the  inner  side  of  the 
closing  opercula  of  the  deciduous  dental  follicles,  commencing 
behind  the  incisors  and  proceeding  onwards  through  the  rest;  these 
are  the  rudiments  of  the  follicles  or  cavities  of  reserve  of  the  four 
permanent  incisors,  two  permanent  canines,  and  the  four  bicuspides. 
As  the  secondary  dental  groove  gradually  closes,  these  folhcular 
inflections  of  the  mucous  membrane  are  converted  into  closed 
cavities  of  reserve,  which  recede  from  the  surface  of  the  gum  and  lie 
immediately  to  the  inner  side  and  in  close  contact  with  the  dental 
sacs  of  the  deciduous  teeth,  being  enclosed  in  their  submucous  cel- 
lular tissue.  At  about  the  fifth  month  the  anterior  of  these  cavities 
of  reserve  dilate  at  their  distal  extremities,  and  a  fold  or  papilla 
projects  into  their  fundus,  constituting  the  rudiment  of  the  germ  of 
the  permanent  tooth ;  at  the  same  time  two  small  opercular  folds 
*■  are  produced  at  their  proximal  or  small  extremities,  and  convert 
them  into  true  dental  sacs. 

During  the  fifth  month  the  posterior  part  of  the  primitive  dental 
groove  behind  the  sac  of  the  last  deciduous  tooth  has  remained 
open,  and  in  it  has  developed  the  papilla  and  follicle  of  the  first  per- 
manent molar.     Upon  the  closure  of  this  follicle  by  its  opercula. 


DEVELOPEMENT    OF    TEETH.  67 

the  secondary  dental  groove  upon  the  summit  of  its  crown  forms  a 
large  cavity  of  reserve,  lying  in  contact  with  the  dental  sac  upon 
the  one  side  and  with  the  gum  upon  the  superficial  side.  At  this 
period  the  deciduous  teeth,  and  the  sacs  of  the  ten  anterior  perma- 
nent teeth,  increase  so  much  in  size,  without  a  corresponding 
lengthening  of  the  jaws,  that  the  first  permanent  molars  are  gra- 
dually pressed  backwards  and  upwards  into  the  maxillary  tubero- 
sity in  the  upper  jaw,  and  into  the  base  of  the  coronoid  process  of 
the  lower  jaw;  a  position  which  they  occupy  at  the  eighth  and 
ninth  months  of  foetal  fife.  In  the  infant  of  seven  or  eight  months 
the  jaws  have  grown  in  length,  and  the  first  permanent  molar 
returns  to  its  proper  position  in  the  dental  range.  The  cavity  of 
reserve,  which  had  been  previously  elongated  by  the  upward  move- 
ment of  the  first  permanent  molar,  now  dilates  into  the  cavity  which 
that  tooth  has  just  quitted ;  a  papilla  is  developed  from  its  fundus, 
the  cavity  becomes  constricted,  and  the  dental  sac  of  the  second 
molar  tooth  is  formed,  still  leaving  a  portion  of  the  great  cavity  of 
reserve  in  connexion  with  the  superficial  side  of  the  sac.  As  the 
jaws  continue  to  grow  in  length,  the  second  permanent  dental  sac 
descends  from  its  elevated  position  and  advances  forwards  into  the 
dental  range,  following  the  same  curve  with  the  first  permanent 
molar.  The  remainder  of  the  cavity  of  reserve,  already  length- 
ened backwards  by  the  previous  position  of  the  second  molar,  again 
dilates  for  the  last  time,  developes  a  papilla  and  sac  in  the  same 
manner  with  the  preceding,  and  forms  the  third  permanent  molar 
or  wisdom  tooth,  which,  at  the  age  of  nineteen  or  twenty,  upon 
the  increased  growth  of  the  jaw,  follows  the  course  of  the  first  and 
second  molars  into  the  dental  range. 

From  a  consideration  of  the  foregoing  phenomena,  Mr.  Goodsir 
has  divided  the  process  of  dentition  into  three  natural  stages : — 
1,  folhcular;  2,  saccular;  3,  eruptive.  The  first,  or  follicular 
stage,  he  makes  to  include  all  the  changes  which  take  place  from 
the  first  appearance  of  the  dental  groove  and  papillos  to  the  closure 
of  their  follicles ;  occupying  a  period  which  extends  from  the  sixth 
week  to  the  fourth  or  fifth  month  of  intra-uterine  existence.  The 
second,  or  saccular  stage,  comprises  the  period  when  the  follicles 
S;re  shut  sacs,  and  the  included  papillae,  pulps ;  it  commences  at  the 
fourth  and  fifth  months  of  intra-uterine  existence,  and  terminates 
for  the  median  incisors,  at  the  seventh  or  eighth  month  of  infantile 
life,  and  for  the  wisdom  teeth  at  about  the  twenty-first  year.  The 
third,  or  eruptive  stage,  includes  the  completion  of  the  teeth,  the 
eruption  and  shedding  of  the  temporary  set,  the  eruption  of  the  per- 
manent, and  the  necessary  changes  in  the  alveolar  processes.  It 
extends  from  the  seventh  month  till  the  twenty-first  year. 

"  The  anterior  -permanent  molar,"  says  Mr.  Goodsir,  "is  the  most 
remarkable  tooth  in  man,  as  it  forms  a  transition  between  the  milk 
and  the  permanent  set."  If  considered  anatomically,  i.  e.  in  its 
developement  from  the  primitive  dental  groove,  by  a  papilla  and 
follicle,  "  it  is  decidedly  a  milk  tooth ;"  if  physiologically,  "  as  the 


68  GROWTH  OF  TEETH. 

most  efficient  grinder  in  the  adult  mouth,  we  must  consider  it  a  per- 
manent tooth."  "  It  is  a  curious  circumstance,  and  one  which  will 
readily  suggest  itself  to  the  surgeon,  that  laying  out  of  view  the 
wisdom  teeth,  which  sometimes  decay  at  an  early  period  from 
other  causes,  the  anterior  molars  are  the  permanent  teeth  which 
most  frequently  give  way  first,  and  in  the  most  symmetrical  manner 
and  at  the  same  time,  and  frequently  before  the  milk  set." 

GroficLh  of  Teeth. — Immediately  that  the  dental  follicles  have  been 
closed  by  their  opercula,  the  pulps  become  moulded  into  the  form  of 
the  future  teeth ;  and  the  bases  of  the  molars  divided  into  two  or 
three  portions,  representing  the  future  fangs.  The  dental  sac  is 
composed  of  two  layers,  an  internal  or  vascular  layer,  which  was 
originally  a  part  of  the  mucous  surface  of  the  mouth,  and  a  cellulo- 
fibrous  layer,  analogous  to  the  corium  of  the  mucous  membrane. 
Upon  the  formation  of  this  sac  by  the  closure  of  the  follicle,  the 
mucous  membrane  resembles  a  serous  membrane  in  being  a  shut  sac, 
and  may  be  considered  as  consisting  of  a  tunica  propria,  which  invests 
the  pulp ;  and  a  timica  reflexa,  which  is  adherent  by  its  outer  surface 
with  the  structures  in  the  jaM^  and  by  the  inner  surface  is  free,  being 
separated  from  the  pulp  by  an  intervening  cavity.  As  soon  as  the 
moulding  of  the  pulp  has  commenced,  this  cavity  increases  and  be- 
comes filled  with  a  gelatinous  granular  substance,  the  enamel  organ, 
which  is  adherent  to  the  whole  internal  surface  of  the  tunica  reflexa, 
but  not  to  the  tunica  propria  and  pulp.  At  the  same  period,  viz. 
during  the  fourth  or  fifth  month,  a  thin  lamina  of  ivory  is  secreted 
by  the  pulp,  and  deposited  upon  its  most  prominent  point :  if  the 
tooth  be  incisor  or  canine,  the  secreted  layer  has  the  form  of  a 
small  hollow  cone  ;  if  molar,  there  will  be  four  or  five  small  cones 
corresponding  with  the  number  of  tubercles  on  its  crown.  These 
cones  are  united  by  the  secretion  of  additional  layers,  the  pulp 
becomes  gradually  surrounded  and  diminishes  in  size,  depositing 
fresh  layers  during  its  retreat  into  the  jaws  until  the  entire  tooth 
with  its  fangs  is  completed,  and  the  small  cavitas  pulpse  of  the  per- 
fect tooth  alone  remains,  communicating  through  the  opening  in  the 
apex  of  each  fang  with  the  dental  vessels  and  nerves.  The  number 
of  roots  appears  to  depend  upon  the  number  of  nervous  filaments 
sent  to  each  pulp.  When  the  secretion  of  the  ivory  has  commenced, 
the  enamel  organ  becomes  transformed  into  a  laminated  tissue, 
corresponding  with  the  direction  of  the  fibres  of  the  enamel,  and  the 
crystalline  substance  of  the  enamel  is  secreted  into  its  meshes  by 
the  vascular  lining  of  the  sac. 

The  cemenium  appears  to  be  formed  at  a  later  period  of  life,  either 
by  a  deposition  of  osseous  substance  by  that  portion  of  the  dental  sac 
which  continues  to  enclose  the  fang,  and  acts  as  its  periosteum,  or  by 
the  conversion  of  that  membrane  itself  into  bone;  the  former  supposi- 
tion is  the  more  probable. 

The  secretion  of  ivory  commences  in  the  first  permanent  molar  pre- 
viously to  birth. 

Eruption. — Wlicn  the  crown  of  the  toolh  has  been  formed  and 
coated  with  cnarnel,  and  the  fan<:r  has  grown  to  liie  bottom  of  its 


TEETH ERUPTION.  69 

socket  by  the  progressive  lengthening  of  the  pulp,  the  deposition  of 
ivory,  and  the  adhesion  of  the  ivory  to  the  contiguous  portion  of  the 
sac,  the  pressure  of  the  socket  causes  the  reflected  portion  of  the  sac 
and  the  edge  of  the  tooth  to  approach,  and  the  latter  to  pass  through 
the  gum.  The  sac  has  thereby  resumed*  its  original  follicular  con- 
dition, and  has  become  continuous  with  the  mucous  membrane  of  the 
mouth.  The  opened  sac  nov^  begins  to  shorten  more  rapidly  than  the 
fang  lengthens,  and  the  tooth  is  quickly  drawn  upwards  by  the  con- 
traction, leaving  a  space  between  the  extremity  of  the  unfinished 
root  and  the  bottom  of  the  socket,  in  which  the  growth  and  comple- 
tion of  the  fang  is  more  speedily  effected. 

During  the  changes  which  have  here  been  described  as  taking 
place  among  the  dental  sacs  contained  within  the  jaws,  the  septa 
between  the  sacs,  which  at  first  were  composed  of  spongy  tissue, 
soon  became  fibrous,  and  were  afterwards  formed  of  bone,  which 
was  developed  from  the  surface  and  proceeded  by  degrees  more 
deeply  into  the  jaws,  to  constitute  the  alveoli.  The  sacs  of  the  ten 
anterior  permanent  teeth,  at  first  enclosed  in  the  submucous  cellular 
tissue  of  the  deciduous  dental  sacs,  and  received  during  their  growth 
into  crypts  situated  behind  the  deciduous  teeth,  advanced  by  degrees 
beneath  the  fangs  of  those  teeth,  and  became  separated  from  them 
by  distinct  osseous  alveoli.  The  necks  of  the  sacs  of  the  permanent 
teeth,  by  which  they  originally  communicated  with  the  mucous 
lining  of  the  secondary  groove,  still  exist,  in  the  form  of  minute  ob- 
literated cords,  separated  from  the  deciduous  teeth  by  their  alveolus, 
but  communicating  through  a  minute  osseous  canal  with  the  fibrous 
tissue  of  the  palate,  immediately  behind  the  corresponding  deciduous 
teeth.  "  These  cords  and  foramina  are  not  obhterated  in  the  child," 
says  Mr.  Goodsir,  "either  because  the  cords  are  to  become  useful 
as  ' gubernacula'  and  the  canals  as  ^itinera  dentium;'  or,  much  more 
probably,  in  virtue  of  a  law,  which  appears  to  be  a  general  one  in 
the  developement  of  animal  bodies,  viz :  that  parts,  or  organs,  lohick 
have  once  acted  an  important  -part,  however  atrophied  they  may  after- 
wards become,  yet  never  altogether  disappear,  so  long  as  they  do  not 
interfere  with  other  parts  or  functions."" 

Succession. — The  periods  of  appearance  of  the  teeth  are  extremely 
irregular ;  it  is  necessary,  therefore  to  have  recourse  to  an  average, 
which,  for  the  temporary  teeth,  may  be  stated  as  follows,  the  teeth 
of  the  lower  jaw  preceding  those  of  the  upper  by  a  short  interval : 

7th  month,  two  middle  incisors.     18th  month,  canine. 

9th  month,  two  lateral  incisors.     24th  month,  two  last  molares. 

12th  month,  first  molares. 

The  periods  for  the  permanent  teeth  are, 
6|  year,  first  molares.  10th  year,  second  bicuspides. 

7th  year,  two  middle  incisors.       11th  to  12th  year,  canine. 
8th  year,  two  lateral  incisors.       12th  to  13th  year,  second  molares. 
9th  year,  first  bicuspides.  17th  to  21st  year,  last  molares. 

*  Mr.  Nasmy  til  is  of  opinion  that  it  is  "  by  a  process  of  absorption,  and  not  of  disrup- 
tion, that  the  tooth  is  emancipated."     Medico-chirurgical  Transactions.     1839. 


70 


OS  HYOIDES. 


OS    HYOIDES. 


The  OS  hyoides  forms  the  second  arch  developed  from  the  cranium, 
and  gives  support  to  the  tongue,  and  attachment  to  numerous  mus- 
cles in  the  neck.     It  is  named  from  its  resemblance  to  the  Greek  let- 
ter u,  and  consists  of  a  central  portion,  or 
Fig.  26*  body,  of  two  larger  cornua,  which  project 

backwards  from  the  body,  and  two  lesser 
cornua,  which  ascend  from  the  angles  of 
union  between  the  body  and  the  greater 
cornua. 

The  body  is  somewhat  quadrilateral,  rough 
and  convex  on  its  anterior  surface,  where  it 
gives  attachment  to  muscles ;  concave  and 
smooth  on  the  posterior  surface,  by  which  it  lies  in  contact  with  the 
epiglottis.  The  greater  cornua  are  flattened  from  above  downwards, 
and  terminated  posteriorly  in  a  tubercle ;  and  the  lesser  cornua, 
conical  in  form,  give  attachment  to  the  stylo-hyoid  ligaments.  In 
early  age  and  in  the  adult,  the  cornua  are  connected  with  the  body 
by  cartilaginous  surfaces  and  ligamentous  fibres ;  but  in  old  age  they 
become  united  by  bone. 

Deve/opement — By  Jive  centres,  one  for  the  body,  and  one  for 
each  cornu. 

Attachment  of  Muscles. — To  eleven  pairs  ;  sterno-hyoid,  thyro- 
hyoid, omo-hyoid,  pulley  of  the  digastricus,  stylo-hyoid,  mylo-hyoid, 
genio-hyoid,  genio-hyo-glossus,  hyo-glossus,  lingualis,  and  middle 
constrictor  of  the  pharynx.  It  also  gives  attachment  to  the  stylo- 
hyoid, thyro-hyoid,  and  hyo-epiglottic  ligaments,  and  to  the  thyro- 
hyoidean  membrane. 

THORAX  AND  UPPER  EXTREMITY. 

The  bones  of  the  thorax  are  the  sternum  and  ribs ;  and,  of  the 
upper  extremity,  the  clavicle,  scapula,  humerus,  ulna,  and  radius, 
bones  of  the  carpus,  metacarpus,  and  phalanges. 

Sternum. — The  sternum  (fig.  27)  is  situated  in  the  middle  line  of 
the  front  of  the  chest ;  it  is  flat,  or  slightly  concave  in  front,  and 
convex  behind ;  broad  and  thick  above,  and  flattened  and  pointed 
below.     It  consists  of  three  pieces ;  superior,  middle,  and  inferior. 

The  su-pcrior  (1)  is  nearly  quadrilateral ;  broad  and  thick  above, 
and  somewhat  narrowed  at  its  junction  with  the  middle  piece.  At 
each  superior  angle  is  a  deep  articular  depression  for  the  clavicle, 
and  on  either  side  two  notches,  for  the  articulation  of  the  cartilage 
of  the  first  rib,  and  one  half  of  the  second. 

The  middle  piece  (2),  considerably  longer  than  the  superior,  is 

*  The  OS  hyoides  seen  from  before.  1.  The  anterior  convex  side  of  the  body.  2. 
The  great  cornu  of  the  loft  side.  3.  The  lesser  eornu  of  the  same  side.  The  cornua 
were  ossified  to  tlic  body  of  the  bone  in  the  specimen  from  which  this  figure  was 
drawn. 


EIES TRUE  AND  FALSE. 


71 


broad  in  the  middle,  and  somewhat  narrower  at  each  extremity. 
It  presents  on  each  side  six  articular  notches,  for  the  lower  half  of 
the  second  rib,  the  four  next  ribs,  and  the  upper  half  of  the  seventh. 

The  inferior  'piece,  or  ensiform  cartilage  (3),  is  the  smallest  of  the 
three,  often  merely  cartilaginous,  and  very  various  in  appearance, 
being  sometimes  pointed,  at  other  times  broad  and  thin,  and  at 
other  times  again,  perforated  by  a  round  hole,  or  bifid.  It  presents 
a  notch  at  each  side  for  the  articulation  of  the  lower  half  of  the 
cartilage  of  the  seventh  rib. 

Developement. — By  a  number  of  centres,  varying  from  six  to 
fourteen. 

Articulations. — With  sixteen  bones ;  viz.  with  the  clavicle,  and 
with  seven  true  ribs  at  each  side. 

Attachment  of  Muscles. — To  nine  pairs  and  one  single  muscle ; 
viz.  to  the  pectoralis  major,  sterno-mastoid,  sterno-hyoid,  sterno- 
thyroid, triangularis  sterni,  aponeurosis  of  the  obliquus  externus, 
internus,  and  transversahs  muscles,  rectus,  and  diaphragm. 

Ribs. — The  ribs  are  twelve  in  number  at  each  side ;  the  seven 
first  are  connected  with  the  sternum,  and  hence  named  t7'ue ;  the 
remaining  five  are  the  false  ribs ; 
and  the  two  last  shorter  than  the  ^ig.  27.* 

rest,  and  free  at  their  extremi- 
ties, are  the  floating  ribs.  The 
ribs  increase  in  length  from  the 
first  to  the  eighth,  whence  they 
again  diminish  to  the  twelfth; 
in  breadth  they  diminish  gra- 
dually from  the  first  to  the  last. 
Each  rib  presents  an  external 
and  internal  surface,  a  superior 
and  inferior  border,  and  two 
extremities ;  it  is  curved  to  cor- 
respond with  the  arch  of  the 
thorax,  and  twisted  upon  itself, 
so  that  when  laid  upon  its  side, 
one  end  is  tilted  up,  while  the 
other  rests  upon  the  surface. 

The  external  surface  is  con- 
vex, and  marked  by  the  attach- 
ment of  muscles;  the  internal 

is  flat,  and  corresponds  with  the  pleura;  the  superior  border  is 
rounded ;  and  the  inferior  sharp  and  grooved  upon  its  inner  side, 
for  the  attachment  of  the  intercostal  muscles.     Near  its  vertebral 

*  An  anterior  view  of  the  thorax.  1.  The  superior  piece  of  the  sternum.  2.  The 
middle  piece.  3.  The  inferior  piece,  or  ensiform  cartilage.  4.  The  first  dorsal 
vertebra,  o.  The  last  dorsal  vertebra.  6.  The  first  rib.  7.  Its  head.  8.  Its  neck 
resting  against  the  transverse  process  of  the  first  dorsal  vertebra.  9.  Its  tuberosity! 
10.  1  he  seventh  or  last  true  rib.  1  ].  The  costal  cartilages  of  the  true  ribs.  12  The 
two  last  false  ribs-the  floating  ribs.  13.  The  groove  along  the  lower  border  of  the 
nb  tor  the  lodgment  of  the  intercostal  vessels  and  nerve. 


72  COSTAL  CARTILAGES. 

extremity,  the  rib  is  suddenly  bent  upon  itself;  and  opposite  the 
bend,  upon  the  external  surface,  is  a  rough  oblique  ridge,  which 
gives  attachment  to  a  tendon  of  the  sacro-lumbalis  muscle,  and  is 
called  the  angle.  The  distance  between  the  vertebral  extremity 
and  the  angle  increases  gradually,  from  the  second  to  the  eleventh 
rib.  Beyond  the  angle  is  a  rough  elevation,  the  tuberosity ;  and 
immediately  at  the  base  and  rather  below  the  tuberosity  a  smooth 
surface  for  articulation  with  the  extremity  of  the  transverse  pro- 
cess of  the  corresponding  vertebra.  Beyond  the  tuberosity  is  the 
neck ;  and  at  the  extremity  of  the  neck  an  oval  surface,  the  head, 
divided  by  a  ridge  into  two  facets  for  articulation  with  two  con- 
tiguous vertebras.  The  posterior  surface  of  the  neck  is  rough,  for 
the  attachment  of  the  middle  costo-transverse  ligament ;  and  upon 
its  upper  border  is  a  crest,  which  gives  attachment  to  the  anterior 
costo-transverse  ligament.  The  sternal  extremity  is  flattened,  and 
presents  an  oval  depression,  into  which  the  costal  cartilage  is 
received. 

The  ribs  that  demand  especial  consideration  are  the  first,  and  the 
three  last. 

The^rs^  is  the  shortest  rib ;  it  is  broad  and  flat,  and  placed  hori- 
zontally at  the  upper  part  of  the  thorax,  the  surfaces  looking  up- 
wards and  downwards,  in  place  of  forwards  and  backwards  as  in 
the  other  ribs.  At  about  the  anterior  third  of  the  upper  surface  of 
the  bone,  and  near  its  internal  border,  is  a  tubercle  which  gives  at- 
tachment to  the  scalenus  anticus  muscle,  and  immediately  before 
and  behind  this  tubercle,  a  shallow  oblique  groove,  the  former  for 
the  subclavian  vein,  and  the  latter  for  the  subclavian  artery.  Near 
the  posterior  extremity  of  the  bone  is  a  thick  and  prominent  tube- 
rosity, with  a  smooth  articular  surface  for  the  transverse  process  of 
the  first  dorsal  vertebra.  There  is  no  angle.  Beyond  the  tube- 
rosity is  a  narrow  constricted  neck ;  and  quite  at  the  extremity,  a 
head,  presenting  a  single  articular  surface.  The  second  rib  ap- 
proaches in  some  of  its  characters  to  the  first. 

The  tenth  rib  has  a  single  articular  surface  on  its  head. 

The  eleventh  and  twelfth  have  each  a  single  articular  surface  on 
the  head,  no  neck  or  tuberosity,  and  are  pointed  at  the  extremity. 
The  eleventh  has  a  slight  ridge,  representing  the  angle,  and  a  shal- 
low groove  on  the  lower  border ;  the  twelfth  has  neither. 

Costal  Cartilages. — The  costal  cartilages  (fig.  27.  11, 11)  serve 
to  prolong  the  ribs  forwards  to  the  anterior  part  of,  the  chest,  and 
contribute  mainly  to  the  elasticity  of  the  thorax.  They  are  broad 
at  their  attachment  to  the  ribs,  and  taper  slightly  towards  their  oppo- 
site extremities ;  they  gradually  diminish  in  breadth  from  the  first  to 
the  last,  and  increase  in  length  from  the  first  to  the  seventh,  and  then 
diminish  to  the  last. 

The  seven  first  cartilages  articulate  with  the  sternum ;  the  three 
next  with  the  lower  border  of  the  cartilage  immediately  preceding. 
All  the  cartilages  of  the  false  ribs  terminate  by  pointed  extremities. 

Developement. — The  ribs  are  developed  by  three  centres ;  one  for 


CLAVICLE SCAPULA.  73 

the  central  part,  one  for  the  head,  and  one  for  the  tuberosity.     The 
two  last  have  only  one  centre. 

Articulations. — Each  rib  articulates  with  two  vertebra3,  and  one 
costal  cartilage,  with  exception  of  the  first,  tenth,  eleventh,  and 
twelfth,  which  articulate  each  with  a  single  vertebra  only. 

Attachment  of  Muscles. — To  the  ribs  and  their  cartilages  are  at- 
tached twenty-two  pairs,  and  one  single  muscle.  To  the  cartilages, 
the  subclavius,  sterno-thyroid,  pectoralis  major,  internal  oblique,  rec- 
tus, transversalis,  diaphragm,  triangularis  sterni,  internal  and  exter- 
nal intercostals.  To  the  rihs,  the  intercostal  muscles,  scalenus 
anticus,  scalenus  posticus,  pectoralis  minor,  serratus  magnus,  obli- 
quus  externus,  obliquus  internus,  latissimus  dorsi,  quadratus  lumbo- 
rum,  serratus  posticus  superior,  serratus  posticus  inferior,  sacro- 
lumbalis,  longissimus  dorsi,  cervicalis  ascendens,  levatores  costarum, 
transversalis,  and  diaphragm. 

Clavicle. — The  clavicle  is  a  long  bone  shaped  somewhat  like  the 
italic  letter  S,  the  convexity  at  one  end  being  anterior  and  internal, 
at  the  other  posterior  and  external.  The  inner  half  of  the  bone  is 
rounded  or  irregularly  quadrilateral,  and  terminates  in  a  broad  arti- 
cular surface.  The  outer  half  is  flattened  from  above  downwards, 
and  broad  at  its  extremity,  the  articular  surface  occupying  only  part 
of  its  extent.  The  upper  surface  is  smooth  and  convex,  and  partly 
subcutaneous ;  while  the  under  surface  is  rough  and  depressed,  for 
the  insertion  of  the  subclavius  muscle.  At  the  sternal  extremity  of 
the  under  surface  is  a  very  rough  prominence,  which  gives  attach- 
ment to  the  rhomboid  hgament ;  and  at  the  other  extremity  a  rough 
tubercle  and  ridge,  for  the  coraco-clavicular  ligament.  The  open- 
ing for  the  nutritious  vessels  is  seen  upon  the  under  surface  of  the 
bone. 

Developement. — By  two  centres ;  one  for  the  shaft,  and  one  for  the 
anterior  prominence  of  the  sternal  extremity. 

Articulations. — With  the  sternum  and  scapula. 

Attachment  of  Muscles. — To  six;  the  sterno-mastoid,  trapezius, 
pectoralis  major,  deltoid,  subclavius,  and  sterno-hyoid. 

Scapula. — The  scapula  is  a  flat  triangular  bone,  situated  upon  the 
posterior  aspect  and  side  of  the  thorax.  It  is  divisible  into  an  ante- 
rior and  posterior  surface,  superior,  inferior,  and  posterior  border, 
anterior,  superior,  and  inferior  angle  and  processes. 

The  anterior  surface,  or  subscapular  fossa,  is  concave  and  irregu- 
lar, and  marked  by  several  oblique  ridges.  The  whole  concavity  is 
occupied  by  the  subscapularis  muscle,  with  the  exception  of  a  small 
triangular  portion  near  the  superior  angle.  The  posterior  surface  or 
dorsum  is  convex,  and  unequally  divided  into  two  portions  by  the 
spine ;  that  portion  above  the  spine  is  the  supra-spinous  fossa ;  and 
that  below,  the  infra-spinous  fossa. 

The  superior  border  is  the  shortest  of  the  three ;  it  is  thin  and  con- 
cave, and  terminated  at  one  extremity  by  the  superior  angle,  and  at 
the  other  by  the  coracoid  process.     At  its  inner  termination,  and 

10 


74 


Fig.  28.^ 


formed  partly  by  the  base  of  the  coracoid  process,  is  tlie  supra-sca- 
pular notch,  for  the  transmission  of  the  supra-scapular  nerve. 

.The  inferior  or  anterior  border  is  thick,  and  marked  by  several 
grooves,  and  depressions ;  it  terminates  superiorly  at  the  glenoid 
cavity,  and  inferiorly  at  the  inferior  angle.  Immediately  below  the 
glenoid  cavity  is  a  rough  ridge,  M^hich  gives  origin  to  the  long  head 
of  the  triceps  muscle.  Upon  the  posterior  surface  of  the  border  is  a 
depression  for  the  teres  minor;  and  upon  its  anterior  surface  a 
deeper  groove  for  the  teres  major :  near  the  inferior  angle  is  a  pro- 
jecting lip,  which  increases  the  surface  of  origin  of  the  latter  muscle. 
The  posterior  border,  the  longest  of  the  three,  is  also  named  the 
base.  It  is  intermediate  in  thickness  between  the  superior  and 
inferior,  and  convex,  being  considerably  inflected  forwards  towards 
the  superior  angle. 

The  anterior  angle  is  the  thickest  part  of  the  bone,  and  forms  the 

head  of  the  scapula ;  it  is  immediately 
surrounded  by  a  depressed  surface, 
the  neck.  The  head  presents  a  shal- 
low pyriform  articular  surface,  the 
glenoid  cavity,  having  the  pointed  ex- 
tremity upwards  ;  and  at  its  apex  is  a 
rough  depression,  which  gives  attach- 
ment to  the  long  tendon  of  the  biceps. 
The  superior  angle  is  thin  and  pointed. 
The  inferior  angle  is  thick  and  smooth 
upon  the  external  surface  for  the  ori- 
gin of  the  teres  major,  and  for  a  large 
bursa  over  which  the  upper  border  of 
the  latissimus  dorsi  muscle  plays. 

The  spine  of  the  scapula  crosses  the 
upper  part  of  its   dorsum;    it  com- 
mences at  the  posterior  border  by  a 
smooth  triangular 'surface  over  which 
the  trapezius  glides  upon  a  bursa,  and 
terminates  at  the  point  of  the  shoulder 
in  the  acromion  process.     The  upper  border  of  the  spine  is  rough 
and  subcutaneous,  and  gives  attachment  by  two  projecting  lips  to 
the  trapezius  and  deltoid  muscles. 

The  acromion  is  somewhat  triangular  and  flattened  from  above 
downwards ;  it  overhangs  the  glenoid  cavity,  the  upper  surface 
being  rough  and  subcutaneous,  the  lower  smooth  and  correspond- 
ing with  the  shoulder-joint.     Near  its  extremity  is  an  oval  articular 

*  A  posterior  view  of  the  scapula.  1.  The  supra-spinous  fossa.  2.  The  infra- 
spinous  fosHa.  3.  The  superior  border.  4.  The  supra-scapular  notch.  5.  The 
anterior  or  inferior  border.  6.  The  head  of  the  scapula  and  glenoid  cavity.  7.  The 
inferior  angle.  8.  The  neck  of  the  scapul;i,  the  ridge  opposite  to  the  number  gives 
origin  to  the  long  head  of  the  triceps.  9.  The  posterior  border  or  base  of  the  scapula. 
10.  The  spine.  11.  The  triangular  smooth  surface,  over  which  the  tendon  of  the 
trapezius  glides.  12.  The  acromion  process.  13.  One  of  the  nutritious  foramina. 
14.  The  coracoid  process. 


HUMERUS.      "  75 

surface,  for  the  end  of  the  clavicle.  The  nutritious  foramina  of 
the  scapula  are  situated  in  the  base  of  the  spine. 

The  caracoid  process  is  a  thick,  round,  and  curved  process  of 
bone,  arising  from  the  upper  part  of  the  neck  of  the  scapula,  and 
overarching  the  glenoid  cavity.  It  is  about  two  inches  in  length 
and  very  strong;  it  gives  attachment  to  several  ligaments  and 
muscles. 

DevelopemenL — By  six  centres;  one  for  the  body,  one  for  the 
coracoid  process,  two  for  the  acromion,  one  for  the  posterior  border, 
and  one  for  the  inferior  angle. 

Articulations. — With  the  clavicle  and  humerus. 

Attachment  of  Muscles. — To  sixteen ;  by  its  anterior  surface  to 
the  subscapularis ;  posterior  surface,  supra-spinatus  and  infra-spi- 
natus;  superior  border,  omo-hyoid;  posterior  border,  levator  an- 
guli  scapulae,  rhomboideus  minor,  rhomboideus  major,  and  serratus 
magnus ;  anterior  border,  long  head  of  the  triceps,  teres  minor,  and 
teres  major ;  upper  angle  of  the  glenoid  cavity,  to  the  long  tendon 
of  the  biceps ;  spine  and  acromion,  to  the  trapezius  and  deltoid ; 
coracoid  process,  to  the  pectoralis  minor,  short  head  of  the  biceps, 
and  coraco-brachialis.  The  lig-aments  attached  to  the  coracoid 
process  are,  the  coracoid,  coraco-clavicular,  and  coraco-humeral, 
and  the  costo-coracoid  membrane. 

Humerus. — The  humerus  is  a  long  bone  divisible  into  a  shaft  and 
two  extremities. 

The  swpenor  ex^remz'/y  presents  a  rounded  head;  a  constriction 
immediately  around  the  base  of  the  head,  the  neck ;  a  greater  and 
a  lesser  tuberosity.  The  greater  tuberosity  is  situated  most  exter- 
nally, and  is  separated  from  the  lesser  by  a  vertical  furrow — the 
bicipital  groove, — which  lodges  the  long  tendon  of  the  biceps.  The 
edges  of  this  groove  below  the  head  of  the  bone  are  raised  and 
rough,  and  are  called  the  anterior  and  posterior  bicipital  ridge;  the 
former  serves  for  the  insertion  of  the  pectoralis  major  muscle,  and 
the  latter  for  the  teres  major. 

The  constriction  of  the  bone  below  the  tuberosities  is  the  sur- 
gical neck,  and  is  so  named,  in  contradistinction  to  the  true  neck, 
from  being  the  seat  of  the  accident  called  by  surgical  writers  frac- 
ture of  the  neck  of  the  humerus. 

The  shaft  of  the  bone  is  prismoid  at  its  upper  part,  and  flattened 
from  before  backwards  below.  Upon  its  outer  side,  at  about  its 
middle,  is  a  rough  triangular  eminence,  which  gives  insertion  to 
the  deltoid ;  and  immediately  on  each  side  of  this  eminence  is  a 
smooth  depression,  corresponding  with  the  two  heads  of  the  bra- 
chialis  antic  us.  Upon  the  inner  side  of  the  middle  of  the  shaft  is  a 
ridge,  for  the  attachment  of  the  coraco-brachiaUs  muscle ;  and 
behind,  an  oblique  and  shallow  groove,  which  lodges  the  musculo- 
spiral  nerve  and  superior  profunda  artery.  The  foramen  for  the 
medullary  vessels  is  situated  upon  the  inner  surface  of  the  shaft  of 
the  bone,  a  little  below  the  coraco-brachial  ridge ;  it  is  directed 
downwards. 


76 


HUMERUS ULNA. 


The  lower  extremity  is  flattened  from  before  backwards,  and  is 
terminated  interiorly  by  a  long  articular  surface,  divided  into  two 
parts  by  an  elevated  ridge.    The  external  portion  of 
Fig.  29.*        the   articular  surface  is  a  rounded  protuberance, 
which  articulates  with  the   cup-shaped   depression 
on  the  head  of  the  radius  ;  the  internal  portion  is  a 
'^>3      concave  and  pulley-like  surface,  which  articulates 
^'  with   the   ulna.     Projecting   beyond  the   articular 

surface  on  each  side  are  the  external  and  internal 
condyle,  the  latter  being  considerably  the  longer ; 
and  running  upwards  from  the  condyles  upon  the 
borders  of  the  bone  are  the  condyloid  ridges,  of 
which  the  external  is  the  most  prominent.  Immedi- 
ately in  front  of  the  articular  surface  is  a  small  de- 
pression, for  receiving  the  coronoid  process  of  the 
ulna  during  flexion  of  the  fore-arm ;  and  immedi- 
ately behind  it  a  large  and  deep  fossa,  for  containing 
the  olecranon  process  in  extension. 

Developement. — By  seven  centres ;  one  for  the 
shaft,  one  for  the  upper  extremity,  one  for  the 
greater  tuberosity,  one  for  the  rounded  protuberance, 
and  one  for  the  trochlear  portion  of  the  articular 
surface,  and  one  for  each  condyle. 

Articulations. — With  the  glenoid  cavity  of  the 
scapula,  and  with  the  ulna  and  radius. 

Attachment  of  Muscles. — To  twenty-four ;  by  the 
greater  tuberosity  to  the  supra-spinatus,infra-spinatus, 
and  teres  minor;  lesser  tuberosity,  subscapularis;  anterior  bicipital 
ridge,  pectoralis  major ;  posterior  bicipital  ridge  and  groove,  teres 
major  and  latissimus  dorsi ;  shaft,  external  and  internal  heads  of  the 
triceps,  deltoid,  coraco-brachialis,  and  brachialis  anticus ;  external 
condyloid  ridge  and  condyle,  extensors  and  supinators  of  the  fore- 
arm, viz.  supinator  longus,  extensor  carpi  radialis  longior,  extensor 
carpi  radialis  brevior,  extensor  communis  digitorum,  extensor 
minimi  digiti,  extensor  carpi  ulnaris,  anconeus,  and  supinator 
brevis ;  internal  condyle,  flexors  and  one  pronator,  viz.  pronator 
radii  teres,  flexor  carpi  radialis,  palmaris  longus,  flexor  sublimis 
digitorum,  and  flexor  carpi  ulnaris. 

Ulna. — The  ulna  is  a  long  bone,  divisible  into  a  shaft  and  two 
extremities.  The  upper  extremity  is  large,  and  forms  principally 
the  articulation  of  the  elbow ;  while  the  lower  extremity  is  small, 


*  The  humerus  of  the  right  side;  its  anterior  surface.  ].  The  shaft  of  the  bone. 
2.  The  head.  3.  The  anatomical  neck,  4.  Tlie  greater  tuberosity.  .5.  Tlie  lesser 
tuberosity.  6.  The  bicipital  groove.  7.  Tiie  anterior  bicipital  ridge.  8.  Tlie  posterior 
bicipital  ridge.  9.  The  rough  surface  into  which  the  deltoid  is  inserted.  10.  The  nu- 
tritious foramen.  11.  The  rounded  protuberance  of  tlie  articular  surface.  12.  Tlie 
pulley-like  surface.  13.  The  external  condyle.  14.  The  internal  condyle.  15.  The 
external  condyloid  ridge.  16.  The  internal  condyloid  ridge.  17.  The  fossa  for  the 
coronoid  proccBS  of  the  ulna. 


ULNA.  77 

and   excluded   from   the   wrist-joint    by   an   inter-articular   fibro- 
cartilage. 

The  superior  extremity  presents  a  semilunar  concavity  of  large 
size,  the  greater  sigmoid  notch,  for  articulation  with  the  humerus  ; 
and  upon  the  outer  side  a  lesser  sigmoid  notch,  which  articulates 
with  the  head  of  the  radius.  Bounding  the  greater  sigmoid  notch 
posteriorly  is  the  olecranon  process ;  and  overhanging  it  in  front,  a 
pointed  eminence  with  a  rough  triangular  base — the  coronoid  process. 
Behind  the  lesser  sigmoid  notch,  and  .extending  downwards  on  the 
side  of  the  olecranon,  is  a  triangular  rough  surface,  for  the  an- 
coneus muscle ;  and  upon  the  posterior  surface  of  the  olecranon 
another  triangular  surface,  which  is  subcutaneous. 

The  shaft  is  prismoid  in  form,  and  presents  three  surfaces, — an- 
terior, posterior,  and  internal ;  and  three  borders.  The  anterior 
surface  is  occupied  by  the  flexor  profundus  digitorum  for  the  upper 
three-fourths  of  its  extent ;  and  below  by  a  depression,  for  the  pro- 
nator quadratus  muscle.  A  little  above  its  middle  is  the  nutritious 
foramen,  which  is  directed  upwards.  Upon  the  posterior  surface  at 
the  upper  part  of  the  bone  is  the  triangular  rough  depression  for  the 
anconeus  muscle,  bounded  inferiorly  by  an  oblique  ridge  which 
runs  downwards  from  the  posterior  extremity  of  the  lesser  sigmoid 
notch.  Below  the  ridge  the  surface  is  marked  into  several  grooves, 
for  the  attachment  of  the  extensor  ossis  metacarpi,  extensor  secundi 
internodii,  and  extensor  indicis  muscle.  The  internal  surface  is 
covered  in  for  its  whole  extent  by  the  flexor  carpi  ulnaris. 
The  anterior  border  is  rounded,  and  gives  origin  by  its  lower  fourth 
to  the  pronator  quadratus ;  the  posterior  is  more  prominent,  and 
affords  attachment  to  the  flexor  carpi  ulnaris  and  extensor  carpi 
ulnaris.  At  its  upper  extremity  it  expands  into  the  triangular  sub- 
cutaneous surface  of  the  olecranon.  The  external  or  radial  border 
is  sharp  and  prominent,  for  the  attachment  of  the  interosseous 
membrane. 

The  lower  extremity  terminates  in  a  small  rounded  head,  from  the 
side  of  which  projects  the  styloid  process.  Upon  the  posterior 
surface  of  the  head  is  a  groove,  for  the  tendon  of  the  flexor  carpi 
ulnaris  ;  and  upon  the  side  opposite  to  the  styloid  process  a  smooth 
surface,  for  articulation  with  the  side  of  the  radius. 

Developement. — By  four  centres  ;  one  for  the  shaft,  one  for  each 
extremity,  and  one  for  the  olecranon. 

Articulations. — With  two  bones ;  the  humerus  and  radius. 

Attachment  of  Muscles. — To  twelve;  by  the  olecranon,  to  the 
triceps  extensor  cubiti,  one  head  of  the  flexor  carpi  ulnaris,  and  to 
the  anconeus  ;  by  the  coronoid  process,  to  the  brachialis  anticus, 
pronator  radii  teres,  flexor  sublimis  digitorum,  and  flexor  profundus 
digitorum  ;  by  the  shaft,  to  the  flexor  profundis  digitorum,  flexor 
carpi  ulnaris,  pronator  quadratus,  anconeus,  extensor  carpi  ulnaris, 
extensor  ossis  metacarpi  poUicis,  extensor  secundi  internodii  poUicis, 
and  extensor  indicis. 

Radius. — The  radius  is  the  rotatory  bone  of  the  fore-arm;  it  is  di- 


78 


RADIUS. 


Fig.  30. 


visible  into  a  shaft  and  two  extremities :  unlike  the  iiliia,  its  upper 
extremity  is  small,  and  merely  accessoiy  to  the  formation  of  the 
elbow-joint;  while  the  lower  extremity  is  large,  and 
forms  almost  solely  the  joint  of  the  wrist. 

The  swperior  extremity  presents  a  rounded  head, 
depressed  upon  its  upper  surface  into  a  shallow  cup. 
Around  the  margin  of  the  head  is  a  smooth  articular 
siu'face,  which  is  broad  on  the  inner  side,  where  it 
articulates  with  the  lesser  sigmoid  notch  of  the  ulna, 
and  narrow  in  the  rest  of  its  circumference,  to  play 
in  the  orbicular  licrament.  Beneath  the  head  is  a 
romid  constricted  neck;  and  beneath  the  neck  on  its 
internal  aspect  a  prominent  process — the  tuberosity. 
The  surface  of  the  tuberosity  is  partly  smooth,  and 
partly  rough ;  rough  below,  where  it  receives  the  at- 
tachment of  the  tendon  of  the  biceps:  and  smooth 
above,  where  a  bursa  is  inteiiDosed  between  the  ten- 
don and  the  bone. 

The  shaft  of  the  bone  is  prismoid,  and  presents 
three  surfaces.  The  anterior  surface  is  somewhat 
concave  superiorly,  where  it  lodges  the  flexor  longus 
poUicis;  and  flat  below,  where  it  supports  the  pro- 
nator quadratus.  At  about  the  upper  third  of  this 
surface  is  the  nuti'itious  foramen,  which  is  directed 
upwards.  The  posterior  surface  is  round  above,  where 
it  supports  the  supinator  brevis  muscle,  and  marked  by  several  shal- 
low oblique  grooves  below,  which  afford  attachment  to  the  extensor 
muscles  of  the  thumb.  The  external  surface  is  roimded  and  con- 
vex, and  marked  by  an  oblique  ridge,  which  extends  from  the  tube- 
rosity to  the  styloid  process  at  the  lower  extremity  of  the  bone. 
Upon  the  inner  margin  of  the  bone  is  a  sharp  and  prominent  crest, 
which  gives  attachment  to  the  interosseous  membrane.  The  lower 
extremity  of  the  radius  is  broad  and  triangular,  and  provided  with 
two  articular  surfaces ;  one  at  the  side  of  the  bone,  which  is  con- 
cave to  receive  the  rounded  head  of  the  ulna ;  the  other  at  the  ex- 
tremity, and  marked  by  a  slight  ridge  into  two  facets, — one  exter- 
nal and  triangular,  corresponding  with  the  scaphoid;  the  other 
square,  with  tlie  semilunar  bone.  Upon  the  outer  side  of  the  ex- 
tremity is  a  strong  conical  projection,  tlie  styloid  process,  which 
gives  attachment  by  its  base  to  the  tendon  of  the  supinator  longus, 
by  its  apex  to  the  external  lateral  ligament  of  the  wrist  joint,  and  by 
its  inner  side  to  the  triangular  interarticular  cartilage. 


*  The  two  bones  of  the  fore-arm  seen  from  the  front.  1.  The  shaft  of  tlic  ulna.  2, 
The  greater  sig-moid  notch.  3.  Tlie  lesser  sigmoid  notch,  with  which  the  head  of  the 
radius  is  articulated.  4.  The  olecranon  process.  5.  The  coronoid  process.  6.  The 
nutritious  foramen.  7.  The  sliarp  ridges  upon  the  two  bones  to  which  the  interosseous 
membrane  is  attached.  8.  The  rounded  head  at  tlie  lower  extremity  of  the  ulna.  9. 
The  styloid  process.  10.  The  shaft  of  the  radius.  11.  Its  head  surrounded  by  the 
smooth  border  for  articulation  with  the  orbicular  ligament.  12.  Tlie  neck  of  the  radius. 
13,  Its  tuberosity.  14.  The  oblique  line.  15.  'I'hc  lower  extremity  oi"  the  bone.  1.6. 
Its  styloid  proees.s. 


CARPUS. 


79 


-With  four  bones ;   humerus,  uhia,  scaphoid,  and 


Fiff.  31* 


Immediately  in  front  of  the  styloid  process  is  a  groove,  -which 
lodges  the  tendons  of  the  extensor  ossis  metacarpi  poUicis,  and  ex- 
tensor primi  internodii;  and  behind  the  process  a  broader  groove, 
for  the  tendons  of  the  extensor  carpi  radialis  longior  and  brevior,  and 
extensor  secundi  internodii ;  behind  this  is  a  prominent  ridge,  and  a 
deep  and  narrow  groove,  for  the  tendon  of  the  extensor  indicis ;  and 
still  farther  back  part  of  a  broad  groove,  completed  by  the  ulna,  for 
the  tendons  of  the  extensor  communis  digitorum. 

Developement. — By  t/iree  centres ;  one  for  the  shaft,  and  one  for 
each  extremity. 

Articulation  s.- 
semilunar. 

Attachment  of  Muscles. — To  nine;  by  the  tuberosity  and  obUque 
ridge,  to  the  biceps,  supinator  brevis,  pronator  radii  teres,  flexor  sub- 
limis  digitorum,  and  pronator  quadratus ;  by  the  anterior  surface,  to 
the  flexor  longus  pollicis  and  pronator  quadratus;  by  the  posterior 
surface,  to  the  extensor  ossis  metacarpi  pollicis,  and  extensor  primi 
internodii ;  and  by  the  styloid  process,  to  the  supinator  longus. 

Carpus. — The  bones  of  the  carpus  are  eight  in  number,  they  are 
arranged  in  two  rows.  In  the  first  row,  commencing  from  the 
radial  side,  are  the  os  scaphoides,  semilunare,  cuneiforme,  pisiforme ; 
and  in  the  second  row,  in  the  same  order,  the  os  trapezium,  trape- 
zoides,  OS  magnum  and  unciforme. 

The  scaphoid  bone  is  named  from  bear- 
ing some  resemblance  to  the  shape  of  a 
boat,  being  broad  at  one  end,  and  nar- 
rowed like  a  prow  at  the  opposite,  con- 
cave on  one  side,  and  convex  upon  the 
other.  It  is,  however,  more  similar  in 
form  to  a  cashew  nut,  flattened  and  con- 
cave upon  one  side.  If  carefully  examined, 
it  will  be  found  to  present  a  convex  and  a 
concave  surface,  a  convex  and  a  concave 
border,  a  broad  end,  and  a  narroio  and 
pointed  extremity — the  tuberosity. 

To  ascertain  to  which  hand  it  belongs, 
let  the  student  hold  it  horizontally,  so  that 
the  convex  surface  may  look  backwards 
{i.  e.  towards  himself,)  and  the  convex  bor- 
der  upwards:   the   broad  extremity  will   indicate  its  appropriate 

*  A  diagram  showing  the  dorsal  surface  of  the  bones  of  the  carpus,  with  their  articu- 
lations.— Tlie  right  hand.  R.  The  lower  end  of  the  radius.  U.  Tlie  lower  extremity 
of  the  ulna.  F.  Tlie  inter-articular  fibro-cartilage  attached  to  the  styloid  process  of 
the  ulna,  and  to  the  margin  of  the  articular  surface  of  the  radius.  S.  The  scaphoid 
bone :  the  numeral  (5)  indicates  the  number  of  bones  with  which  it  articulates.  L. 
The  semilunare  articulating  with  five  bones.  C.  The  cuneiforme,  articulating  with 
three  bones.  P.  The  pisiforme,  articulating  with  the  cuneiforme  only.  T.  The  first 
bone  of  the  second  row — the  trapezium,  articulating  with  fciu-  bones.  T.  The  second 
bone — the  trapezoides,  articulating  also  with  four  bones.  M.  The  os  magnum,  articu- 
lating with  seven.  U.  The  unciforme  articulating  with  five.  The  numerals,  1,  3,  1, 
2,  1,  on  the  metacarpal  bones,  refer  to  the  number  of  their  articulations  with  the  car- 
pal bones. 


80  SCAPHOID  BONE SEMILUNARE CUNEIFORME. 

hand;  if  it  be  directed  to  the  right,  the  bone  belongs  to  the  right; 
and  if  to  the  left,  to  the  left  carpus. 

Articulations. — With  /lue  bones;  by  its  convex  surface  with  the 
radius ;,  by  its  concave  surface,  with  the  os  magnum  and  semilunare ; 
and  by  the  extremity  of  its  upper  or  dorsal  border,  with  the  trapezium 
and  trapezoides. 

Attachments. — By  its  tuberosity  to  the  abductor  pollicis,  and 
amiular  hgament. 

The  semilunar  bone  may  be  known  by  having  a  crescentic  con- 
cavity, and  a  somewhat  crescentic  outline.  It  presents  for  exami- 
nation four  articular  surfaces  and  two  extremities;  the  articular 
surfaces  are,  one  concave,  one  convex,  and  two  lateral — one  lateral 
surface  being  crescentic ;  the  other  nearly'-  circular,  and  divided 
o-enerally  into  two  facets :  and  the  extremities,  one  dorsal,  which  is 
quadrilateral,  flat,  and  indented,  for  the  attachment  of  ligaments ; 
the  other  palmar,  which  is  convex,  rounded,  and  of  larger  size. 

To  determine  to  which  hand  it  belongs,  let  the  bone  be  held  per- 
pendicularly, so  that  the  dorsal  or  flat  extremity  look  upwards,  and 
the  convex  side  backwards  (towards  the  holder).  The  circular 
lateral  surface  will  point  to  the  side  corresponding  with  the  hand  to 
which  the  bone  belongs. 

Articulations. — With  Jive  bones,  but  occasionally  with  only  four ; 
by  its  convex  surface,  with  the  radius;  by  its  concave  surface, 
with  the  OS  magnum ;  by  its  crescentic  lateral  facet,  with  the  sca- 
phoid ;  and  by  the  circular  surface,  with  the  cuneiform  bone  and 
with  the  point  of  the  unciform.  This  surface  is  divided  into  two 
parts  by  a  ridge,  when  it  articulates  with  the  unciform  as  well  as 
with  the  cuneiform  bone. 

The  cuneiform  bone,  although  somewhat  wedge-shaped  in  form, 
may  be  best  distinguished  by  a  circular  and  isolated  facet,  which 
articulates  with  the  pisiform  bone.  It  presents  for  examination 
three  surfaces,  a  base,  and  an  apex.  One  surface  is  very  rough 
and  irreo-ular ;  the  opposite  forms  a  concave  articular  surface, 
while  the  third  is  partly  rough  and  partly  smooth,  and  presents 
that  circular  facet  which  is  characteristic  of  the  bone.  The  base 
is  an  articular  surface,  and  the  apex  is  rough  and  pointed. 

To  distinguish  its  appropriate  hand,  let  the  base  be  directed 
backwards  and  the  pisiform  facet  upwards ;  the  concave  articular 
surface  will  point  to  the  hand  to  which  it  belongs. 

Articulations. — With  three  bones,  and  with  the  triangular  fibro- 
cartilagc.  By  the  base,  with  the  semilunare;  by  the  concave  sur- 
face, with  the  unci  forme ;  by  flie  circular  facet,  with  the  pisiforme ; 
and  by  the  superior  angle  of  the  rough  surface,  with  the  fibro- 
cartilagc. 

Tho  pisiform  bone  may  be  recognised  by  its  small  size,  and  by 
possessing  a  single  articular  facet.  If  it  be  examined  carefully,  it 
will  be  observed  to  present  four  sides  and  two  extremities;  one 
side  is  articiilar,  the  smooth  facet  approaching  nearer  to  the 
superior  than  the  inferior  extremity.     The  side  opposite  to  this  is 


trapezitt:m — TRAPEzoror.s.  81 

rounded,  and  the  remaining  sides  are,  one  slightly  concave,  the 
other  slightly  convex. 

If  the  bone  be  held  so  that  the  articular  facet  shall  look  down- 
wards, and  the  extremity  which  overhangs  the  articular  facet 
forwards,  the  concave  side  Avill  point  to  the  hand  to  which  it 
belongs. 

Articulations. — With  the  cuneiform  bone  only. 

Attachments. — To  two  muscles — the  flexor  carpi  ulnaris,  and 
abductor  minimi  digiti ;  and  to  the  annular  ligament. 

The  trapezium  is  too  irregular  in  form  to  be  compared  to  any 
known  object ;  it  may  be  distinguished  by  a  deep  groove  for  the 
tendon  of  the  flexor  carpi  radialis  muscle.  It  is  somewhat  com- 
pressed, and  may  be  divided  into  two  surfaces  which  are  smooth 
and  articular,  and  three  rough  borders.  One  of  the  articular  sur- 
faces is  ovial,  concave  in  one  direction,  and  convex  in  the  other ; 
the  other  is  marked  into  three  facets.  One  of  the  borders  presents 
the  groove  for  the  tendon  of  the  flexor  carpi  radialis,  which  is  sur- 
mounted by  a  prominent  tubercle  for  the  attachment  of  the  annular 
ligament ;  the  other  two  borders  are  rough  and  form  the  outer  side 
of  the  carpus.  The  grooved  border  is  narrow  at  one  extremity 
and  broad  at  the  other,  where  it  presents  the  groove  and  tubercle. 

If  the  bone  be  held  so  that  the  grooved  border  look  upwards 
while  the  apex  of  this  border  be  directed  forwards,  and  the  base 
with  the  tubercle  backwards,  the  concavo-convex  surface  will 
point  to  the  hand  to  which  the  bone  belongs. 

Articulations. — V^iih.  four  bones;  by  the  concavo-convex  surface, 
with  the  metacarpal  bone  of  the  thumb ;  and  by  the  three  facets  of 
the  other  articular  surface,  with  the  scaphoid,  trapezoid,  and  second 
metacarpal  bone. 

Attachments. — To  tico  muscles — flexor  ossis  metacarpi,  and  flexor 
brevis  pollicis ;  and  by  the  tubercle,  to  the  annular  ligament. 

The  trapezoides  is  a  small,  oblong,  and  quadrilateral  bone,  bent 
near  its  middle  upon  itself.  It  presents  four  articular  surfaces  and 
two  extremities.  One  of  the  surfaces  is  concavo-convex, — i.  e.  con- 
cave in  one  direction  and  convex  in  the  other ;  another,  contiguous 
to  the  preceding,  is  concave,  so  as  to  be  almost  angular  in  the 
middle,  and  is  often  marked  by  a  small  rough  depression,  for  an 
interosseous  ligament;  the  two  remaining  sides  SiYejflat,  and  present 
nothing  remarkable.  One  of  the  two  extremities  is  broad  and  of 
large  size, — the  dorsal ;  the  other,  or  palmar,  is  small  and  rough. 

If  the  bone  be  held  perpendicularly,  so  that  the  broad  extremity 
be  upwards,  and  the  concavo-convex  surface  forwards,  the  angular 
concave  surface  will  point  to  the  hand  to  which  the  bone  belongs. 

Articulations. — V^^'iXh.  four  bones  ;  by  the  concavo-convex  surface, 
with  tile  second  metacarpal  bone ;  by  the  angular  concave  surface, 
with  the  OS  magnum ;  and  by  the  other  two  surfaces,  with  the  trape- 
zium and  scaphoid. 

Attachments. — To  the  flexor  brevis  pollicis  muscle. 

The  OS  magnum  is  the  largest  bone  of  the  carpus,  and  is  divisible 

11 


82  OS  3IAGNU3I UNCIFORME, 

into  a  body  and  head.  The  head  is  round  for  the  greater  part  of 
its  extent,  but  is  flattened  on  one  side.  The  hodij  is  irregularly 
quadrilateral,  and  presents  four  sides  and  a  smooth  extremity.  Two 
of  the  sides  are  rough,  the  one  being  square  and  flat — the  dorsal, 
the  other  rounded  and  prominent — the  palmar ;  the  other  two  sides 
are  articular,  the  one  being  concave,  the  other  convex.  The 
extremity  is  a  triangular  articular  sm'face,  divided  into  three  facets. 

If  the  bone  be  held  pei-pendicularly,  so  that  the  articular  extremity 
look  upwards  and  the  broad  dorsal  sui'face  backwards  (towards  the 
holder),  the  concave  articular  surface  will  point  to  the  hand  to  which 
the  bone  belongs. 

Articulations. — With  seven  bones;  by  the  rounded  head,  with  the 
cup  formed  by  the  scaphoid  and  semilunar  bone ;  by  the  side  of  the 
convex  surface,  with  the  trapezoides ;  by  the  concave  surface,  with 
the  unciforme ;  and  by  the  extremity,  with  the  second,  third,  and 
fourth  metacarpal  bones. 

Attachments. — To  the  flexor  brevis  pollicis  muscle. 

The  unciforme  is  a  triangular-shaped  bone,  remarkable  for  a  long 
and  curved  process,  which  projects  from  its  palmar  aspect.  It  pre- 
sents five  surfaces  ; — three  articular,  and  two  free.  One  of  the 
articular  surfaces  is  divided  by  a  slight  ridge  into  two  facets ;  the 
other  two  converge,  and  meet  at  a  flattened  angle.*  One  of  the 
free  surfaces — the  dorsal — is  rough  and  triangular;  the  other — 
palmar,  also  triangular,  but  somewhat  smaller,  gives  origin  to  the 
unciform  process. 

If  the  bone  be  held  perpendicularly,  so  that  the  articular  surface 
with  two  facets  look  upwards,  and  the  unciform  process  back- 
wards (towards  the  holder),  the  concavity  of  the  imciform  process 
will  point  to  the  hand  to  which  the  bone  belongs. 

Articulations. — With  five  bones ;  by  the  two  facets  on  its  base, 
with  the  fourth  and  fifth  metacarpal  bones  ;  by  the  two  lateral  arti- 
culating surfaces,  with  the  magnum  and  cuneiforme ;  and  by  the 
flattened  angle  of  its  apex,  with  the  semilunare. 

Attachments. — To  two  muscles — the  adductor  minimi  digiti,  and 
flexor  brevis  minimi  digiti ;  and  to  the  annular  ligament. 

Developement. — The  bones  of  the  carpus  are  each  developed  by 
a  single  centre. 

The  number  of  articulations  which  each  bone  of  the  carpus  pre- 
sents with  surrounding  bones,  may  be  expressed  in  figures,  which 
will  materially  facilitate  their  recollection ;  the  number  for  the  first 
row  is  5531,  and  for  the  second  4475. 

Metacarpus. — The  bones  of  the  metacarpus  are  five  in  number. 
They  arc  long  bones,  divisible  into  a  head,  shaft,  and  base. 

The  head  is  rounded  at  the  extremity,  and  flattened  at  each  side, 
for  the  insertion  of  strong  ligaments ;  the  shaft  is  prismoid,  and 
marked  deeply  on  each  side,  for  the  attachment  of  the  interossei 
muscles;  and  the  base  is  irregularly  quadrilateral  and  rough,  for 

*  When  the  uncilbrmc  does  not  articulate  with  tlie  sctnilunurc,  tliis  angle  is  siiarp. 


METACARPUS. 


83 


Fig.  32.* 


the  insertion  of  tendons  and  ligaments.  The  base  presents  three 
articular  surfaces,  one  at  each  side,  for  the  adjoining  metacarpal 
bones ;  and  one  at  the  extremity  for  the 
carpus. 

The  metacarpal  bone  of  the  thumb  is 
one-third  shorter  than  the  rest,  flattened 
and  broad  on  its  dorsal  aspect,  and  convex 
on  its  palmar  side;  the  articular  surface 
of  the  head  is  not  so  round  as  that  of  the 
other  metacarj^al  bones ;  and  the  base  has 
a  single  concavo-convex  surface,  to  arti- 
culate with  the  similar  surface  of  the  tra- 
pezium. 

The  metacarpal  bones  of  the  different 
fingers  may  be  distinguished  by  certain 
obvious  characters.  The  base  of  the 
metacarpal  bone  of  the  index  finger  is  the 
largest  of  the  four,  and  presents  four  arti- 
cular surfaces.  That  of  the  middle  finger 
may  be  distinguished  by  a  rounded  pro- 
jecting process  upon  the  radial  side  of  its 
base,  and  two  small  circular  facets  upon 

its  ulnar  lateral  surface.  The  base  of  the  metacarpal  bone  of  the 
ring-finger  is  small  and  square,  and  has  two  small  circular  facets  to 
correspond  with  those  of  the  middle  metacarpal.  The  metacarpal 
bone  of  the  little  finger  has  only  one  lateral  articular  surface. 

Developement. — By  two  centres  ;  one  for  the  shaft,  and  one  for  the 
digital  extremity. 

Articulations. — The  first  with  the  trapezium  ;  second,  with  the 
trapezium,  trapezoides,  and  os  magnum,  and  with  the  middle  meta- 
carpal bone ;  third,  or  middle,  with  the  os  magnum,  and  adjoining 
metacarpal  bones ;  fourth,  with  the  os  magnum  and  unciforme,  and 
with  the  adjoining  metacarpal  bones  ;  and  fifth,  with  the  unciforme, 
and  with  the  metacarpal  bone  of  the  ring-finger. 

The  figures  resulting  from  the  nuinber  of  articulations  which  each 
metacarpal  bone  possesses,  taken  from  the  radial  to  the  ulnar  side, 
are  13121. 

Attachment  of  Muscles. — To  the  metacarpal  bone  of  the  thumb, 
three — the  flexor  ossis  metacarpi,  extensor  ossis  metacarpi  and  first 
dorsal  interosseous ;  of  the  index  finger,  fve — the  extensor  carpi 
radialis  longior,  flexor  carpi  radialis,  first  and  second  dorsal  interos- 
seous, and  first  palmar  interosseous ;  of  the  middle  finger,  four — 
the  extensor  carpi  radialis  brevior,  adductor  pollicis,  and  second 

*  The  hand  viewed  upon  its  anterior  or  palmar  aspect.  ].  The  scaphoid  bone. 
2.  The  semilunare.  .3.  The  cuneiforme.  4.  The  pisiforme.  5.  The  trapezium. 
G.  The  groove  in  the  trapezium  tiiat  lodges  the  tendon  of  the  flexor  carpi  radialis. 
7.  The  trapezoides.  8.  The  os  magnum.  9.  The  unciforme.  10,  10.  The  five  meta- 
carpal bones.  11,  11.  The  first  row  of  phalanges.  12,  12.  The  second  row.  13,  13. 
The  third  row,  or  ungual  plialanges.  14.  The  first  phalanx  of  the  tlunnb.  1.5.  The 
■second  and  last  phalanx  of  the  thumb. 


84  METACARPUS PHALANGES. 

and  third  dorsal  interosseous  ;  of  the  ring-finger,  three — the  third 
and  fourth  dorsal  interosseous,  and  second  palmar  ;  and  of  the  httle 
finger, /owr — extensor  carpi  ulnaris,  adductor  minimi  digiti,  fourth 
dorsal  and  third  palmar  interosseous. 

Phalanges. — The  phalanges  are  the  bones  of  the  fingers ;  they 
are  named  from  their  arrangement  in  rows,  and  are  fourteen  in 
number, — three  to  each  finger,  and  two  to  the  thumb.  In  confor- 
mation they  are  long  bones,  divisible  into  a  shaft,  and  two  extre- 
mities. 

The  shaft  is  compressed  from  before  backwards,  convex  on  its 
•posterior  surface,  and  flat  with  raised  edges  in  front.  The  meta- 
carpal extremity  of  the  first  row  is  a  simple  concave  articular  surface 
— of  the  other  two  rows  a  double  concavity,  separated  by  a  slight 
ridge.  The  digital  extremities  of  the  first  and  second  row  present 
a  pulley-like  surface,  concave  in  the  middle,  and  convex  on  each 
side.  The  ungual  extremity  of  the  last  phalanx  is  broad,  rough 
and  expanded  into  a  semilunar  crest. 

Developement. — By  two  centres  ;  one  for  the  shaft,  and  one  for 
the  metacarpal  extremity. 

Articulations. — The  first  row,  with  the  metacarpal  bones  and 
second  row  of  phalanges  ;  the  second  row,  with  the  first  and  third ; 
and  the  third,  with  the  second  row. 

Attachment  of  Muscles. — To  the  base  of  the j^r^^  phalanx  of  the 
thumb  four  muscles — abductor  polhcis,  flexor  brevis  poUicis, 
adductor  poUicis,  and  extensor  primi  internodii ;  and  to  the  second 
phalanx,  two — the  flexor  longus  pollicis,  and  extensor,  secandi  in- 
ternodii. To  the  first  -phalanx  of  the  second,  third,  and  fourth 
fingers,  one  dorsal  and  one  palmar  interosseous,  and  to  the  first 
phalanx  of  the  little  finger,  the  abductor  minimi  digiti,  flexor  brevis 
minimi  digiti,  and  one  palmar  interosseous.  To  the  second  phalanges 
the  flexor  sublimis  and  extensor  communis  digitorum ;  and  to  the 
last  phalanges — the  flexor  profundus  and  extensor  communis  digi- 
torum. 

PELVLS  AND  LOWER  EXTREMITY. 

The  bones  of  the  pelvis  are  the  two  ossa  innominata,  the  sacrum, 
and  the  coccyx  ;  and  of  the  lower  extremity,  the  femur,  patella,  tibia 
and  fibula,  tarsus,  metatarsus,  and  j)ha]angcs. 

Os  Innominatum. — The  os  innorninatiiin  is  an  irregular  flat  bone, 
consisting  in  the  young  subject  of  three  parts,  which  meet  at  the 
acetabulum.  Hence  it  is  usually  described  in  the  adult  as  divisible 
into  three  portions, — ilium,  ischium,  and  pubis.  The  ilium  is  the 
superior  broad  and  expanded  portion  which  forms  the  prominence 
of  the  hip,  and  articulates  with  the  sacrum.  The  ischium  is  the 
inferior  and  strong  part  of  the  bone  ctn  which  we  sit.  The  pubis  is 
that  portion  which  forms  the  front  of  tlie  pelvis,  and  gives  support 
to  the  external  organs  of  generation. 

The  ilium,  may  bo  described  as  divisible  into  an  internal  and  ex- 
ternal surface,  a  crest,  and  an  anterior  and  posterior  border. 


85 


•'-kiS^' 


The  internal  surface  is  bounded  above  by  the  crest,  below  by  a 
prominent  hne — the  Hnea  ilio-pectinea,  and  before  and  behind  by 
the  anterior  and  posterior  bor- 
ders ;  it  is  concave  and  smooth  ^i&-  ^^•* 
for  the  anterior  tw^o-thirds  of  its 
extent,  and  lodges  the  iliacus 
muscle.  The  posterior  third  is 
rough,  for  articulation  with  the 
sacrum,  and  is  divided  into  two 
parts  by  a  deep  groove ; — an 
anterior  or  auricular  -portion, 
which  is  shaped  like  the  pinna, 
and  coated  by  cartilage  in  the 
fresh  bone;  and  a  posterior 
portion,  which  is  very  rough, 
for  the  attachment  of  interos- 
seous ligaments. 

The  external  surface  is 
rough,  partly  convex,  and 
partly  concave;  it  is  bounded 
above  by  the  crest;  below,  by 
a  prominent  arch,  which  forms 
the  upper  segment  of  the  acetabulum;  and  before  and  behind 
by  the  anterior  and  posterior  borders.  Crossing  this  surface  in  an 
arched  direction,  from  the  anterior  extremity  of  the  crest  to  a  notch 
upon  the  lower  part  of  the  posterior  border,  is  a  groove,  which 
lodges  the  gluteal  vessels  and  nerve — the  superior  curved  line ;  and 
below  this,  at  a  short  distance,  a  rough  ridge, — the  inferior  curved 
line.  The  surface  included  between  the  superior  curved  line  and 
the  crest,  gives  origin  to  the  gluteus  medius  muscle ;  that  between 
the  curved  lines,  to  the  gluteus  minimus ;  and  the  rough  interval 
between  the  inferior  curved  line  and  the  arch  of  the  acetabulum,  to 
one  head  of  the  rectus.  The  posterior  sixth  of  this  surface  is  rough 
and  raised,  and  gives  origin  to  part  of  the  gluteus  maximus. 

The  crest  of  the  ilium  is  arched  and  sigmoid  in  its  direction,  being 
bent  inwards  at  its  anterior  termination,  and  outwards  towards  the 
posterior.  It  is  broad  for  the  attachment  of  three  planes  of  muscles, 
which  are  connected  with  its  external  and  internal  borders  or  lips, 
and  with  the  intermediate  space. 

The  anterior  border  is  marked  by  two  projections, — the  anterior 
superior  spinous  process,  which  is  the   anterior  termination  of  the 

*  The  OS  innominatum  of  the  right  side.  1.  Tlie  ilium  ;  its  external  surface.  2. 
The  ischium.  3.  The  os  pubis.  4.  The  crest  of  the  ilium.  5.  The  superior  curved 
line.  6.  The  inferior  curved  line.  7.  The  surface  for  the  gluteus  maximus.  8.  The 
anterior  superior  spinous  process.  9.  The  anterior  inferior  spinous  process.  10.  The 
posterior  superior  spinous  process.  11.  The  posterior  inferior  spinous  process.  12. 
The  spine  of  the  ischium.  ]3.  The  great  sacro-ischiatic  notch.  14.  The  lesser  sacro- 
ischiatic  notch.  1.5.  The  tuberosity  of  the  ischium,  showing  its  three  facets.  16. 
The  ramus  of  the  ischium.  17.  The  body  of  the  os  pubis.  18.  The  ramus  of  the 
pubis. 


86  ISCHIUM OS  PUBIS. 

crest,  and  the  anterior  inferior  spinous  process;  the  two  processes 
bemg  separated  by  a  notch  for  the  attachment  of  the  sartorius 
muscle.  This  border  terminates  inferiorly  in  the  hp  of  the  acetabu- 
him.  The  posterior  border  also  presents  two  projections, — the  poste- 
rior siipeiior  and  the  posterior  inferior  spinous  process, — separated 
by  a  notch.  Inferiorly  this  border  is  broad  and  arched,  and  forms 
the  upper  part  of  the  great  sacro-ischiatic  notch. 

The  ischium  is  divisible  into  a  thick  and  solid  portion — the  body, 
and  into  a  thin  and  ascending  part — the  ramus;  it  may  be  consi- 
dered also,  for  convenience  of  description,  as  presenting  an  external 
and  internal  sm'face,  and  three  borders, — posterior,  inferior,  and 
superior. 

The  external  surface  is  rough,  for  the  attachment  of  muscles ;  and 
broad  and  smooth  above,  where  it  enters  into  the  formation  of  the 
acetabulum.  Below  the  inferior  lip  of  the  acetabulum  is  a  notch, 
which  lodges  the  obturator  externus  muscle  in  its  passage  outwards 
to  the  trochanteric  fossa  of  the  femur.  The  internal  surface  is 
smooth,  and  somewhat  encroached  upon  at  its  posterior  border  by 
the  spine. 

The  posterior  border  of  the  ischium  presents  towards  its  middle  a 
remarkable  projection, — the  spine.  Immediately  above  the  spine  is 
a  notch  of  large  size — the  great  sacro-ischiatic,  and  below  the  spine 
the  lesser  sacro-ischiatic  notch;  the  former  being  converted  into  a 
foramen  by  the  lesser  sacro-ischiatic  ligament,  gives  passage  to  the 
pyriformis  muscle,  and  to  the  gluteal  vessels  and  nerve,  pudic  vessels 
and  nerve,  and  ischiatic  vessels  and  nerves ;  and  the  lesser  com- 
pleted by  the  great  sacro-ischiatic  ligament,  to  the  obturator  internus 
muscle,  and  to  the  internal  pudic  vessels  and  nerve.  The  inferior 
border  is  thick  and  broad,  and  is  called  the  tuberosity.  The  surface 
of  the  tuberosity  is  divided  into  three  facets;  one  anterior,  which  is 
rough  for  the  origin  of  the  semi-membranosus ;  and  two  posterior, 
which  are  smooth,  and  separated  by  a  slight  ridge  for  the  semi-ten- 
dinosus  and  biceps  muscle.  The  inner  margin  of  the  tuberosity  is 
bounded  by  a  sharp  ridge,  which  gives  attachment  to  a  prolongation 
of  the  great  sacro-ischiatic  hgament.  The  superior  border  of  the 
ischium  is  thin,  and  forms  the  lower  circumference  of  the  obturator 
foramen.  The  ramus  of  the  ischium  is  continuous  with  the  ramus 
of  the  pubis,  and  is  slightly  everted. 

The  pubis  is  divided  into  a  horizontal  portion  or  body,  and  a  de- 
scending portion  or  ramus;  it  presents  for  examination  an  external 
and  internal  surface,  a  superior  and  inferior  border,  and  symphysis. 

The  external  surface  is  rough,  for  the  attachment  of  muscles;  and 
prominent  at  its  outer  extremity,  where  it  forms  part  of  the  acetabu- 
lum. H\\e  internal  surf  ace  {'^  smooth..  The  superior  Wc?er  is  marked 
by  a  rough  ridge — the  crest ;  the  inner  termination  of  the  crest  is  the 
angle;  and  the  outer  end,  the  spine  or  tuberosity.  Running  out- 
M'ards  from  the  spine  is  a  sharp  ridge,  the  pectineal  line — or  linea 
ilio-pec tinea,  which  marks  the  brim  of  the  true  pelvis.     In  front  of 


ACETABULUM OBTURATOR  FORAMEN.  87 

the  pectineal  line  is  a  smooth  depression,  which  supports  the  femoral 
vein,  and  a  little  more  externally  an  elevated  prominence,  the  -pec- 
tineal eminence,  which  divides  the  surface  for  the  vein  from  another 
depression  which  overhangs  the  acetabulum,  and  lodges  the  psoas 
and  iliacus  muscles.  The  inferior  border  is  broad  and  deeply- 
grooved,  for  the  passage  of  the  obturator  vessels  and  nerve ;  and 
sharp  upon  the  side  of  the  ramus,  to  form  part  of  the  boundary  of 
the  obturator  foramen.  The  symphysis  is  the  inner  extremity  of  the 
body  of  the  bone ;  it  is  oval  and  rough,  for  the  attachment  of  a  liga- 
mentous structure  analogous  to  the  intervertebral  substance.  The 
ramus  of  the  pubis  descends,  and  is  continuous  with  the  ramus  of 
the  ischium.  Its  inner  border  is  considerably  everted,  to  afford  a 
strong  attachment  to  the  crus  penis. 

The  acetabulum  is  a  deep  cup-shaped  cavity,  situated  at  the  point 
of  union  between  the  ilium,  ischium,  and  pubis ;  a  little  less  than 
two-fifths  being  formed  by  the  ilium,  a  little  more  than  two-fifths 
by  the  ischium,  and  the  remaining  fifth  by  the  pubis.  It  is  bounded 
by  a  deep  rim  or  lip,  which  is  broad  and  strong  above,  where  most 
resistance  is  required,  and  marked  in  front  by  a  deep  notch,  which 
transmits  the  nutrient  vessels  into  the  joint.  At  the  bottom  of  the 
cup,  and  communicating  with  the  notch,  is  a  deep  and  circular  pit, 
which  lodges  a  mass  of  fat,  and  gives  attachment  to  the  broad  ex- 
tremity of  the  ligamentum  teres. 

The  obturator  ox  thyroid  foramen  is  a  large  oval  interval  between  the 
ischium  and  pubis,  bounded  by  a  narrow  rough  margin,  to  which  a 
ligamentous  membrane  is  attached.  The  upper  part  of  the  foramen 
is  increased  in  depth  by  the  groove  in  the  under  surface  of  the  os 
pubis,  which  lodges  the  obturator  vessels  and  nerve. 

Developernent. — By  eight  centres ;  three  principal — one  for  the  ilium, 
one  for  the  ischium,  and  one  for  the  pubis ;  and  five  secondary — one 
for  the  crest  of  the  ilium,  and  one  for  its  anterior  inferior  spinous 
process,  one  for  the  centre  of  the  acetabulum,  one  for  the  tuberosity 
of  the  ischium,  and  one  (not  constant)  for  the  angle  of  the  pubis. 

Articulations. — With  three  bones  ;  sacrum,  opposite  innominatum, 
and  femur. 

Attachment  of  Muscles  and  Ligaments. — Ho  thirty-five  muscles;  to 
the  ilium,  thirteen ;  by  the  outer  lip  of  the  crest,  to  the  obliquus  ex- 
ternus  for  two  thirds,  and  to  the  latissimus  dorsi  for  one-third  its 
length,  and  to  the  tensor  vaginse  femoris  by  its  anterior  fourth ;  by 
the  middle  of  the  crest,  to  the  internal  oblique  for  three-fourths  its 
length,  by  the  remaining  fourth  to  the  erector  spinse ;  by  the  inter- 
nal lip,  to  the  transversalis  for  three-fourths,  and  to  the  quadratus 
lumborum  by  the  posterior  part  of  its  middle  third.  By  the  external 
surface,  to  the  gluteus  medius,  minimus  and  maximus,  and  to  one 
head  of  the  rectus ;  by  the  internal  surface,  to  the  iliacus ;  and  by 
the  anterior  border,  to  the  sartorius,  and  the  other  head  of  the  rectus. 
To  the  ischium  sixteen ;  by  its  external  surface,  the  adductor  magnus 
and  obturator  externus';  by  the  internal  surface,  the  obturator  internus 
and  levator  ani ;  by  the  spine,  the  gemellus  superior,  levator  ani, 


88  PELVIS. 

coccygeus,  and  lesser  sacro-ischiatic  ligament ;  by  the  tuberosity,  the 
biceps,  semi-tendinosus,  semi-membranosus,  gemellus  inferior,  quad- 
ratus  femoris,  erector  penis,  transversus  perinei,  and  great  sacro- 
ischiatic  ligament ;  and  by  the  ramus,  the  graciUs,  accelerator  urince, 
and  compressor  urethrse.  To  the  Y>ubis  ff  teen  ;  by  its  upper  border, 
the  obliquus  externus,  .obliquus  internus,  transversalis,  rectus,  pyra- 
midalis,  pectineus,  and  psoas  parvus ;  by  its  external  surface,  the 
adductor  longus,  adductor  brevis  and  gracilis ;  by  its  internal  surface, 
the  levator  ani,  compressor  urethrse,  and  obturator  internus ;  and 
by  the  ramus,  the  adductor  magnus,  and  accelerator  urinse. 

PELVIS. 

The  pelvis  considered  as  a  whole  is  divisible  into  a  false  and  true 
pelvis ;  the  former  is  the  expanded  portion,  bounded  on  each  side  by 
the  ossa  ilii,  and  separated  from  the  true  pelvis  by  the  linea  ilio- 
pectinea.  The  true  pelvis  is  all  that  portion  w^hich  is  situated  be- 
neath the  linea  ilio-pectinea.  This  line  forms  the  margin  or  bj^im  of 
the  true  pelvis,  while  the  included  area  is  called  the  in/ct.  The  form 
of  the  inlet  is  heart-shaped,  obtusely  pointed  in  front  at  the  symphysis 
pubis,  expanded  on  each  side,  and  encroached  upon  behind  by  a 
projection  of  the  upper  part  of  the  sacrum,  which  is  named  the  pro- 
montory. The  cavity  is  somewhat  encroached  upon  at  each  side 
by  a  smooth  quadrangular  plane  of  bone,  corresponding  with  the 
internal  surface  of  the  acetabulum,  and  leading  to  the  spine  of  the 
ischium.  In  front  are  two  fossae  around  the  obturator  foramina,  for 
lodging  the  obturator  internus  muscle,  at  each  side.  The  inferior 
termination  of  the  pelvis  is  very  irregular,  and  is  termed  the  outlet. 
It  is  bounded  in  front  by  the  convergence  of  the  rami  of  the  ischium 
and  pubis,  which  constitute  the  arch  of  the  pubis ;  on  each  side  by 
the  tuberosity  of  the  ischium,  and  by  two  irregular  fissures  formed 
by  the  greater  and  lesser  sacro-ischiatic  notches ;  and  behind  by  the 
inferior  borders  of  the  sacrum,  and  by  the  coccyx. 

The  pelvis  is  placed  obliquely  with  regard  to  the  trunk  of  the  body, 
so  that  a  line  drawn  through  the  central  axis  of  the  inlet,  would  touch 
by  one  extremity  the  lower  part  of  the  sacrum,  and  by  the  other 
would  pass  through  the  umbilicus.  The  axis  of  the  inlet  is  thei^efore 
directed  downwards  and.  hachoards,  while  that  of  the  outlet  points 
dovmvards  and  forivards,  and  corresponds  with  a  line  drawn  from 
the  upper  part  of  the  sacrum,  through  the  centre  of  the  outlet.  The 
axis  of  the  cavity  represents  a  curve,  the  extremities  of  which  will 
be  indicated  by  the  central  points  of  the  inlet  and  outlet.  A  know- 
ledge of  the  direction  of  these  axes  is  most  important  to  the  surgeon, 
as  indicating  the  line  in  which  instruments  should  be  used  in  opera- 
tions upon  the  viscera  of  the  pelvis,  and  the  direction  of"  force  in  the 
removal  of  calculi  from  the  bladder;  and  to  the  accoucheur,  as  ex- 
plaining the  course  of  the  ftKtus  during  parturition. 

There  arc  certain  striking  differences  between  the  male  and 
female  pelvis.     In  the  male  the  bones  are  thicker,  stronger,  and 


PELVIS FEMUR.  89 

more  solid,  and  the  cavity  deeper  and  narrower.  In  the  female  the 
bones  are  lighter  and  more  delicate,  the  iliac  fossae  are  large  and 
the  ilia  projecting ;  the  inlet,  and  the  outlet,  and  the  cavity  are 
large,  and  the  acetabula  farther  removed  from  each  other ;  the 
cavity  is  shallow,  the  tuberosities  widely  separated — the  obturator 
foramina  triangular,  and  the  arch  of  the  pubis  wide.  The  precise 
diameter  of  the  inlet  and  outlet,  and  the  depth  of  the  cavity,  are 
very  important  considerations  to  the  accoucheur. 

The  diameters*  of  the  inlet  or  brim  are  three; — 1,  Antero-pos- 
terior,  sacro-pubic  or  conjugate ;  2,  transverse ;  and  3,  oblique. 
The  antero-posterior  extends  from  the  symphysis  pubis  to  the  middle 
of  the  promontory  of  the  sacrum,  and  measures  four  inches  and  a 
half.  The  transverse  extends  from  the  middle  of  the  brim  on  one 
side  to  the  same  point  on  the  opposite,  and  measures  five  inches  and 
a  quarter.  The  oblique  extends  from  the  sacro-iliac  symphysis  on 
one  side,  to  the  margin  of  the  brim  corresponding  with  the  aceta- 
bulum on  the  opposite,  and  measures  five  inches  and  one-eighth. 

The  diameters  of  the  outlet  are  two,  antero-posterior,  and  trans- 
verse. The  antero-posterior  diameter  extends  from  the  lower  part 
of  the  symphysis  pubis,  to  the  apex  of  the  coccyx ;  and  the  trans- 
verse from  the  first  part  of  one  tuberosity  to  the  same  point  on  the 
opposite  side ;  they  both  measure  four  inches.  The  cavity  of  the 
pelvis  measures  in  depth  four  inches  and  a  half,  posteriorly ;  three 
inches  and  a  half  in  the  middle ;  and  one  and  a  half  at  the  sym- 
physis pubis. 

Femur. — The  femur  is  a  long  bone,  divisible,  like  other  bones  of 
the  same  class,  into  a  shaft,  a  superior  and  an  inferior  extremity. 

At  the  superior  extremity  is  a  rounded  head,  directed  upwards  and 
inwards,  and  marked  just  below  its  centre  by  an  oval  depression  for 
the  ligamentum  teres.  The  head  is  supported  by  a  neck,  which 
varies  in  length  and  obliquity  at  various  periods  of  life,  being  long 
and  oblique  in  the  adult — short  and  almost  horizontal  in  the  aged. 
Externally  to  the  neck  is  a  large  process, — the  trochanter  major, 
which  presents  upon  its  anterior  surface  an  oval  facet,  for  the 
attachment  of  the  tendon  of  the  gluteus  minimus  muscle ;  and  above, 
a  double  facet,  for  the  insertion  of  the  gluteus  medius.  On  its  poste- 
rior side  is  a  vertical  ridge — the  linea  quadrati,  for  the  attachment 
of  the  quadratus  femoris  muscle.  Upon  the  inner  side  of  the  tro- 
chanter major  is  a  deep  pit,  trochanteric  or  digital  fossa,  in  which 
are  inserted  the  tendons  of  the  pyriformis,  gemellus  superior  and 
inferior,  and  obturator  externus  and  internus  muscles.  Passing 
downwards  from  the  trochanter  major  in  front  of  the  bone  is  an 
oblique  ridge,  which  forms  the  inferior  boundary  of  the  neck, — the 
anterior  intertrochanteric  line ;  and  behind,  another  oblique  ridge, 
the  posterior  intertrochanteric  line,  which  terminates  in  a  rounded 

*  These  diameters  are  quoted  from  an  excellent  "  Manual  of  Practical  Midwifery," 
by  Dr.  James  Reid. 

12 


90 


tubercle  upon  the  posterior  and  inner  side  of  the  bone,  the  trochanter 
minor. 

The  shaft  of  the  femur  is  convex  and  rounded  in  front,  and  covered 
with  muscles ;  and  somewhat  concave  and  raised  into  a  rough  and 
prominent  ridge  behind,  the  linea  aspera.  The  linea  aspera  near 
the  upper  extremity  of  the  bone  divides  into  three  branches.  The 
anterior  branch  is  continued  forwards  in  front  of  the  lesser  tro- 
chanter, and  is  continuous  with  the  anterior  intertrochanteric  line  ; 
the  middle  is  continued  directly  upwards  into  the  Hnea  quadrati ; 
and  the  posterior,  broad  and  strongly  marked, 
Fig. 34*  ascends   to   the    base  of  the    trochanter  major. 

Towards  the  lower  extremity  of  the  bone  the  linea 
aspera  divides  into  two  ridges,  which  descend  to 
the  two  condyles,  and  enclose  a  triangular  space 
upon  which  rests  the  popliteal  artery.  The  in- 
ternal condyloid  ridge  is  less  marked  than  the 
external,  and  presents  a  broad  and  shallow 
groove,  for  the  passage  of  the  femoral  artery. 
The  nutritious  foramen  is  situated  in  or  near  the 
linea  aspera,  at  about  one-third  from  its  upper 
extremity,  and  is  directed  obliquely  from  below 
upwards. 

The  lower  extremity  of  the  femur  is  broad  and 
porous,  and  divided  by  a  smooth  depression  in 
front,  and  by  a  considerable  notch  behind,  into 
two  condyles. 

The  external  condyle  is  the  broadest  and  most 
projecting,  and  the  internal  the  narrowest  and 
longest ;  the  difference  in  length  depending  upon 
the  obliquity  of  the  femur,  in  consequence  of  the 
separation  of  the  two  bones  at  their  upper  extre- 
mities by  the  breadth  of  the  pelvis.  The  external 
condyle  is  marked  upon  its  outer  side  by  a  promi- 
nent tuberosity,  which  gives  attachment  to  the 
external  lateral  ligaments;  and  immediately 
beneath  this  is  the  groove  which  lodges  the  ten- 
dinous origin  of  the  poplitcus.  By  the  internal 
surface  it  gives  attachment  to  the  anterior  crucial  ligament  of  the 
knee-joint ;  and  by  its  upper  and  posterior  part,  to  the  external  head 
of  the  gastrocnemius  and  to  the  plantaris.  The  internal  condyle 
projects  upon  its  inner  side  into  a  tuberosity,  to  which  is  attached  the 
internal  lateral  ligament;  above  this  tuberosity,  at  the  extremity  of  the 
internal  condyloid  ridge,  is  a  tubercle,  for  the  insertion  of  the  tendon 

*  The  riglit  femur,  Rccn  upon  the  anterior  aspect.  1.  Tlic  shaft.  2.  The  head.  3. 
The  nock.  4.  Tlie  jrreat  trochanter.  5.  The  anterior  intertrochanteric  Unc.  C.  The 
lesser  trochanter.  7.  The  external  condyle.  8.  'Die  internal  condyle.  9.  The  tuhe- 
rosity  for  the  att.iohment  of  the  external  lateral  ligaments.  ]  0.  The  groove  for  the 
tendon  of  origin  of  the  popliteus  muscle.  11.  The  tuberosity  for  the  attachment  of  the 
internal  lateral  ligament. 


m 


PATELLA TIBIA. 


91 


Fiff.  35  * 


Ui\ 


of  the  adductor  magnus ;  and  beneath  the  tubercle,  upon  the  upper 
surface  of  the  condyle,  a  depression,  from  which  the  internal  head 
of  the  gastrocnemius  arises.  The  outer  side  of  the  internal  condyle 
is  rough  and  concave,  for  the  attachment  of  the  posterior  crucial 
ligament. 

Developement. — By  five  centres;  one  for  the  shaft,  one  for  each 
extremity,  and  one  for  each  trochanter. 

Articulations. — With  three  bones  ;  with  the  os  in- 
nominatum,  tibia,  and  patella. 

Attachment  of  Muscles. — To  iiventy-three ;  by  the 
greater  trochanter,  to  the  gluteus  medius  and  mini- 
mus, pyriformis,  gemellus  superior,  obturator  in- 
ternus,  gemellus  inferior,  obturator  externus,  and 
quadratus  femoris ;  by  the  lesser  trochanter,  to  the 
common  tendon  of  the  psoas  and  ihacus.  By  the 
linea  aspera,  its  outer  lip,  to  the  vastus  externus, 
gluteus  maximus,  and  short  head  of  the  biceps;  by 
its  inner  lip,  to  the  vastus  internus,  pectineus,  ad- 
ductor brevis,  and  adductor  longus;  by  its  middle 
to  the  adductor  magnus ;  by  the  anterior  part  of 
the  bone,  to  the  crurseus  and  subcrurasus ;  by  its 
condyles,  to  the  gastrocnemius,  plantaris  and 
popliteus. 

Patella. — The  patella  is  a  sesamoid  bone,  de- 
veloped in  the  tendon  of  the  quadriceps  extensor 
muscle,  and  usually  described  as  a  bone  of  the 
lower  extremity.  It  is  heart-shaped  in  figure,  the 
broad  side  being  directed  upwards  and  the  apex 
downwards,  the  external  surface  convex,  and  the 
internal  divided  by  a  ridge  into  two  smooth  surfaces, 
to  articulate  with  the  condyles  of  the  femur.  The 
external  articular  surface  corresponding  with  the 
external  condyle  is  the  larger  of  the  two,  and  serves 
to  indicate  the  leg  to  which  the  bone  belongs. 

Articulations. — With  the  two  condyles  of  the  femur. 

Attachment  of  Muscles. — To  four;  the  rectus,  crura3us,  vastus 
internus,  and  vastus  externus,  and  to  the  ligamentum  patella. 

Tibia. — The  tibia  is  the  large  bone  of  the  leg ;  it  is  prismoid  in 
form,  and  divisible  into  a  shaft,  an  upper  and  lower  extremity. 

The  upper  extremittj,  or  head,  is  large,  and  expanded  on  each 
side  into  two  tuberosities.  Upon  the  upper  surface  the  tuberosi- 
ties are  smooth,  to  articulate  with  the  condyles  of  the  femur ;  the 
internal  articular  surface  being  oval  and  oblong,  to  correspond 
with  the  internal  condyle  ;  and  the  external  broad  and  nearly  cir- 

*  A  diagram  of  the  posterior  aspect  of  the  riglit  femur,  showing  the  lines  of  attach- 
ment of  the  muscles.  The  muscles  attached  to  the  inner  lip  are, — p,  tlie  pectineus ; 
a  b,  the  adductor  brevis ;  and  a  I,  the  adductor  longus.  The  middle  portion  is  occupied 
for  its  whole  extent  by  a  m,  the  adductor  magnus  ;  and  is  continuous  superiorly  with 
qf,  the  linea  quadrati,  into  which  the  quadratus  femoris  is  inserted.  The  outer  lip  is 
occupied  by  g  m,  the  glutens  maximus  ;  and  b,  the  short  head  of  the  biceps. 


92 


TIBIA. 


cular.     Between  the  two  articular  surfaces  is  a  spinous  process; 
and  in  front  and  behind  the  spinous  process  a  rough  depression, 
giving   attachment  to  the   anterior    and    posterior 
■  Fig.  36.*       crucial  ligaments.     Between  the  two  tuberosities  on 
4,  the  front  aspect  of  the  bone  is  a  prominent  eleva- 

tion,— the  tubercle, — for  the  insertion  of  the  ligamen- 
-2  tum  patellae,  and  immediately  above  the  tubercle,  a 
smooth  surface  corresponding  with  a  bursa.  Upon 
the  outer  side  of  the  external  tuberosity  is  an  articu- 
lar surface,  for  the  head  of  the  fibula  ;  and  upon  the 
posterior  part  of  the  internal  tuberosity  a  depression, 
for  the  insertion  of  the  tendon  of  the  semi-membra- 
nosus  muscle. 

The  shaft  of  the  tibia  presents  three  surfaces; 
internal,  which  is  subcutaneous  and  superficial; 
external,  which  is  concave  and  marked  by  a  sharp 
ridge,  for  the  insertion  of  the  interosseous  membrane  ; 
and  posterior,  grooved,  for  the  attachment  of  muscles. 
Near  the  upper  extremity  of  the  posterior  surface, 
is  an  oblique  ridge, — the  popliteal  line,  for  the  attach- 
ment of  the  fascia  of  the  popliteus  muscle  ;  and  im- 
mediately below  the  oblique  line,  the  nutritious  canal, 
which  is  directed  downwards. 

The  inferior  extremity  of  the  bone  is  somewhat 
quadrilateral,  and  prolonged  on  its  inner  side  into  a 
large  process,  the  internal  malleolus.  Behind  the  in- 
ternal malleolus,  is  a  broad  and  shallow  groove,  for 
lodging  the  tendons  of  the  tibialis  posticus  and  flexor  longus  digito- 
rum  ;  and  farther  outwards  another  groove,  for  the  tendon  of  the 
flexor  longus  poUicis.  Upon  the  outer  side  the  surface  is  concave 
and  triangular, — rough  above,  for  the  attachment  of  the  interosseous 
ligament ;  and  smooth  below,  to  articulate  with  the  fibula.  Upon 
the  extremity  of  the  bone  is  a  triangular  smooth  surface,  for  articu- 
lating with  the  astragalus. 

Developement. — By  three  centres  ;  one  for  the  shaft,  and  one  for 
each  extremity. 

Jlrtlculatiovs. — With  three  bones  ;  femur,  fibula,  and  astragalus. 
Attachment  of  Muscles. — To  ten ;  by  the  internal  tuberosity,  to 
the  sartorius,  graciUs,  semitendinosus,  and  semimembranosus;  by  the 
external  tuberosity,  to  the  tibialis  anticus  and  extensor  longus  digi- 
torum  ;  by  the  tubercle,  to  the  ligamentum  patellas ;  by  the  external 
surface  of  the  shaft,  to  the  tibialis  anticus ;  and  by  the  posterior 
surface,  to  the  popliteus,  soleus,  flexor  longus  digitorum,  and  tibialis 
posticus. 


*  The  tibia  and  fibula  of  the  right  leg,  articulated  and  seen  from  the  firont.  1.  The 
shaft  of  the  tibia.  2.  The  inner  tuberosity.  3.  The  outer  tuberosity.  4.  The  spinous 
process.  .O.  'I'lic  tubercle.  G.  The  internal  subcutaneous  surface  of  the  shaft.  7.  The 
lower  extremity  of  the  tibia.  8.  The  internal  malleolus.  9.  The  shaft  of  the  fibula.  10. 
Its  upper  extremity.     11.  Its  lower  extremity,  the  external  malleolue. 


FIBULA. 


93 


Fibula. — The  fibula  is  a  long  and  slender  prismoid  bone,  divisible 
into  a  shaft  and  two  extremities. 

The  superior  extremity  or  head  is  thick  and  large,  and  depressed 
upon  the  upper  part  by  a  concave  surface,  which  articulates  with 
the  external  tuberosity  of  the  tibia.  Externally  to  this  surface  is 
a  thick  and  rough  prominence,  for  the  attachment  of  the  external 
lateral  Ugaments  of  the  knee-joint,  terminated  behind  by  a  styloid 
process,  for  the  insertion  of  the  tendon  of  the  biceps. 

The  lower  extremity  is  flattened  from  without  inwards,  and  pro- 
longed downwards  beyond  the  articular  surface  of  the  tibia,  form- 
ing the  external  malleolus.  Its  external  side  presents  a  rough  and 
triangular  surface,  which  is  subcutaneous.  Upon  the  internal  surface 
is  a  smooth  triangular  facet,  to  articulate  with  the  astragalus ; 
and  a  rough  depression,  for  the  attachment  of  the  interosseous 
ligament.  The  anterior  border  is  thin  and  sharp  ;  and  the  posterior, 
broad  and  grooved,  for  the  tendons  of  the  peronei  muscles. 

To  place  the  bone  in  its  proper  position,  and  ascertain  to  which 
leg  it  belongs,  let  the  inferior  or  flattened  extremity  be  directed 
downwards,  and  the  narrow  border  of  the  malleolus  forwards  ;  the 
triangular  subcutaneous  surface  will  then  point  to  the  side  corre- 
sponding with  the  limb  of  which  the  bone  forms  a  part. 

The  shaft  of  the  fibula  is  prismoid,  and  presents  three  surfaces ; 
external,  internal,  and  posterior  ;  and  three  borders.  The  external 
surface  is  the  broadest  of  the  three  ;  it  commences  upon  the  anterior 
part  of  the  bone  above,  and  curves  around  it  so  as  to  terminate 
upon  its  posterior  side  below.  The  surface  is  completely  occupied 
by  the  two  peronei  muscles.  The  internal  surface  commences  on 
the  side  of  the  superior  articular  surface,  and  terminates  below,  by 
narrowing  to  a  ridge,  which  is  continuous  with  the  anterior  border 
of  the  malleolus.  It  is  marked  along  its  middle  by  the  interosseous 
ridge,  which  is  lost  above  and  below  in  the  inner  border  of  the  bone. 

The  posterior  surface  is  twisted  like  the  external,  it  commences 
above  on  the  posterior  side  of  the  bone,  and  terminates  below  on  its 
internal  side ;  at  about  its  middle  is  the  nutritious  foramen,  which  is 
directed  downwards. 

The  internal  border  commences  superiorly  in  common  with  the 
interosseous  ridge,  and  bifurcates  interiorly  into  two  lines,  which 
bound  the  triangular  subcutaneous  space  of  the  external  malleolus. 
The  external  border  begins  at  the  base  of  the  styloid  process  upon  the 
head  of  the  fibula,  and  winds  around  the  bone,  following  the  direc- 
tion of  the  corresponding  surface.  The  posterior  border  is  sharp  and 
prominent,  and  is  lost  inferiorly  in  the  interosseous  ridge. 

Developement. — By  three  centres  ;  one  for  the  shaft,  and  one  for 
each  extremity. 

Articulations. — With  the  tibia  and  astragalus. 

Attachment  of  Muscles. — To  nine;  by  the  head,  to  the  tendon  of  the 
biceps  and  soleus ;  by  the  shaft, — its  external  surface, — to  the 
peroneous  longus  and  brevis ;  internal  surface,  to  the  extensor  longus 
digitorum,  extensor  proprius  poUicis,  peroneus  tertius,  and  tibialis 


94 


TARSUS ASTRAGALUS OS  CALCIS. 


Fiff,  37* 


posticus  ;  by  the  posterior  surface,  to  the  popUteus  and  flexor  longus 
poUicis. 

Tarsus. — The  bones  of  the  tarsus  are  seven  in  number ;  viz.  the 
astragalus,  os  calcis,  scaphoid,  internal,  middle,  and  external 
cuneiform  and  cuboid. 

The  Astragalus  may  be  recognised  by  a  rounded  head,  a  broad 
articular  facet  upon  its  convex  surface,  and  two  articular  facets, 
separated  by  a  deep  groove,  upon  its  concave  surface. 

The  bone  is  divisible  into  a  superior  and  inferior  surface,  an  ex- 
ternal and  internal  border,  and  an  anterior  and  posterior  extremity. 
The  superior  surface  is  convex,  and  presents  a  large  quadrilateral 
and  smooth  facet,  somewhat  broader  in  front  than  behind,  to  articu- 
late with  the  tibia.  The  inferior  surface  is  concave,  and  divided 
by  a  deep  and  rough  groove,  which  lodges  a  strong  interosseous 
ligament,  into  two  facets — the  posterior  large  and  quadrangular, 
and  the  anterior  smaller  and  elliptic, — which  articulate  with  the  os 
calcis.  The  internal  border  is  flat  and  irregular,  and  marked  by  a 
pyriform  articular  surface,  for  the  inner  mal- 
leolus. The  external  presents  a  large  triangular 
articular  facet,  for  the  external  malleolus,  and  is 
rough  and  concave  in  front.  The  anterior  ex- 
tremity presents  a  rounded  head,  surrounded  by 
a  constriction  somewhat  resembling  a  neck  ;  and 
the  posterior  extremity  is  narrow,  and  marked  by 
a  deep  groove,  for  the  tendon  of  the  flexor  longus 
poUicis. 

Hold  the  astragalus  with  the  broad  articular 
surface  upwards,  and  the  rounded  head  for- 
wards; the  triangular  lateral  articular  surface 
will  point  to  the  side  to  which  the  bone  belongs. 
Articulations.-— With,  four  bones;  tibia,  fibula, 
calcis,  and  scaphoid. 

The  Os  Calcis  may  be  known  by  its  large  size 
and  oblong  figure,  by  the  large  and  irregular 
portion  which  forms  the  heel,  and  by  two  articu- 
lar surfaces,  separated  by  a  deep  groove  upon 
its  upper  side. 

The  OS  calcis  is  divisible  into  four  surfaces, 
— superior,  inferior,  external,  and  internal ;  and 
two  extremities, — anterior  and  posterior.  The  superior  surface  is 
convex  behind  and  irregularly  concave  in  front,  where  it  presents 
two  and  sometimes  three  articular  facets,  divided  by  a  broad  and 
shallow  groove,  for  the  interosseous  ligament.   The  inferior  surface 

*  Tlic  dorsal  surface  of  the  left  foot.  1.  The  astragalus;  its  superior  quadrilateral 
and  articular  surface.  2.  The  anterior  extremity  of  the  astrajralus,  which  articulates 
with  (4)  the  seaplioid  bone.  .3.  'J'he  os  calcis.  4.  'I'lic  scaphoid  hone.  5.  The  in- 
ternal cuneiform  bone.  G.  The  middle  cuneiform  bone.  7.  "^I'lie  external  cuneiform 
bone.  8.  The  culjoid  bone.  9.  The  metatarsal  bones  of  the  first  and  second  toes.  10. 
The  first  phalanx  of  the  jrreat  toe.  II.  The  second  plialanx  of  the  great  toe.  12.  The 
first  phalanx  of  the  second  toe.     1.3.  Its  second  phalanx.     H.  Its  third  phalanx. 


SCAPHOID INTERNAL  CUNEIFORM,  95 

is  convex  and  rough,  and  bounded  posteriorly  by  the  two  inferior 
tuberosities,  of  which  the  internal  is  broad  and  large,  and  the 
external  smaller  and  prominent.  The  external  surface  is  convex 
and  subcutaneous,  and  mai'ked  towards  its  anterior  third  by 
two  grooves,  often  separated  by  a  tubercle,  for  the  tendons  of 
the  peroneus  longus  and  brevis.  The  internal  surface  is  concave 
and  grooved,  for  the  tendons  and  vessels  which  pass  into  the  sole  of 
the  foot.  At  the  anterior  extremity  of  this  surface  is  a  projecting 
process,  which  supports  the  anterior  articulating  surface  for  the  as- 
tragalus, and  serves  as  a  pulley  to  the  tendon  of  the  flexor  longus 
digitorum.  Upon  the  anterior  extremity  \s  aflat  articular  surface, 
surmounted  by  a  rough  projection,  which  affords  one  of  the  guides 
to  the  surgeon  in  the  performance  of  Chopart's  operation.  The 
posterior  extremity  is  prominent  and  convex,  and  constitutes  the 
posterior  tuberosity ;  it  is  smooth  for  the  upper  half  of  its  extent, 
where  it  corresponds  with  a  bursa ;  and  rough  below,  for  the  inser- 
tion of  the  tendo  Achillis ;  the  lower  part  of  this  surface  is  bounded 
by  the  two  inferior  tuberosities. 

Articulations. — With  two  bones  ;  the  astragalus  and  cuboid. 

Attachment  of  Muscles. — To  nine  ;  by  the  posterior  tuberosity,  to 
the  tendo  AchiUis  and  plantaris ;  by  the  inferior  tuberosities  and 
under  surface,  to  the  abductor  poUicis,  abductor  minimi  digiti,  flexor 
brevis  digitorum,  flexor  accessorius,  and  flexor  brevis  pollicis,  and 
to  the  plantar  fascia ;  and  by  the  external  surface,  to  the  extensor 
brevis  digitorum. 

The  Scaphoid  bone  may  be  distinguished  by  its  boat-like  figure, 
concave  on  one  side,  and  convex  with  three  facets  upon  the  other. 
It  presents  for  examination  an  anterior  and  posterior  surface,  a  supe- 
rior and  inferior  border,  and  two  extremities — one  broad,  the  other 
pointed  and  thick.  The  anterior  surface  is  convex,  and  divided  into 
three  facets,  to  articulate  with  the  three  cuneiform  bones  ;  and  the 
posterior  concave,  to  articulate  with  the  rounded  head  of  the  astra- 
galus. The  superior  border  is  convex  and  rough,  and  the  inferior 
somewhat  concave  and  irregular.  The  external  extremity  is  broad 
and  rough,  and  the  internal  pointed  and  projecting,  so  as  to  form  a 
tuberosity. 

If  the  bone  be  held  so  that  the  convex  surface  with  three  facets 
look  forwards,  and  the  convex  border  upwards,  the  broad  extremity 
will  point  to  the  side  corresponding  with  the  foot  to  which  the  bone 
belongs. 

Articulations. — ^With  four  bones ;  astragalus  and  three  cuneiform 
bones. 

Attachment  of  Muscles. — To  the  tendon  of  the  tibialis  posticus. 

The  Internal  Cuneiform  may  be  known  by  its  irregular  wedge- 
shape,  and  by  being  larger  than  the  two  other  bones  bearing  the 
same  name.  It  presents  for  examination  a  convex  and  a  concave 
surface,  a  long  and  a  short  articular  border,  and  a  small  and  a 
large  extremity. 

Place  the  bone  so  that  the  small  extremity  may  look  upwards  and 


96  CUNEIFORM  BONES, 

the  long  articular  border  forwards,  the  concave  surface  will  point  to 
the  side  corresponding  with  the  foot  to  which  it  belongs. 

The  convex  surface  is  internal  and  free,  and  assists  in  forming 
the  inner  border  of  the  foot,  and  the  concave  is  external,  and  in 
apposition  "with  the  middle  cuneiform  and  second  metatarsal  bone; 
the  long  border  articulates  with  the  metatarsal  bone  of  the  great 
toe,  and  the  short  border  with  the  scaphoid  bone.  The  small  extre- 
mity is  sharp,  and  the  larger  extremity  rounded  into  a  broad  tuberosity. 
Articulations. — With  four  bones  ;  a  scaphoid,  middle  cuneiform, 
and  the  two  first  metatarsal  bones. 

Attachment  of  Muscles. — To  the  tibialis  anticus,  and  posticus. 
The  Middle  Cuneiform  is  the  smallest  of  the  three;  it  is  wedge- 
shaped,  the  broad  extremity  being  placed  upwards,  and  the  sharp 
end  downwards  in  the  foot.  It  presents  for  examination  four  arti- 
cular surfaces  and  two  extremities.  The  anterior  and  ^posterior  sur- 
faces have  nothing  worthy  of  remark.  One  of  the  lateral  surfaces 
has  a  long  articular  facet,  extending  its  whole  length,  for  the  inter- 
nal cuneiform ;  the  other  has  only  a  partial  articular  facet  for  the 
external  cuneiform  bone. 

If  the  bone  be  held  so  that  the  square  extremity  look  upwards,  the 
broadest  side  of  the  square  being  towards  the  holder,  the  small  and 
partial  articular  surface  will  point  to  the  side  to  which  the  bone 
belongs. 

Articulations. — With  four  bones ;  scaphoid,  internal  and  external 
cuneiform,  and  second  metatarsal  bone. 

Attachment  of  Muscles. — To  the  flexor  brevis  pollicis. 
The  External  Cuneiform  is  intermediate  in  size  between  the  two 
preceding,  and  placed,  like  the  middle,  with  the  broad  end  upwards 
and  the  sharp  extremity  downwards.  It  presents  for  examination 
five  surfaces,  and  a  superior  and  an  inferior  extremity.  The  upper 
extremity  is  flat,  of  an  oblong  square  form,  and  bevelled  posteriorly 
at  the  expense  of  the  outer  surface,  into  a  sharp  edge. 

If  the  bone  be  held  so  that  the  square  extremity  look  upwards 
and  the  sharp  border  backwards,  the  bevelled  surface  will  point  to 
the  side  corresponding  with  the  foot  to  which  the  bone  belongs. 

Articulations. — With  six  bones ;  scaphoid,  middle  cuneiform,  cu- 
boid, and  second,  third,  and  fourth  metatarsal  bones. 

Attachment  of  Muscles. — To  its  inferior  extremity,  the  flexor 
brevis  pollicis. 

The  Cuboid  Bone  is  irregularly  cuboid  in  form,  and  marked 
upon  its  under  surface  by  a  deep  groove,  for  the  tendon  of  the 
peroneus  longus  muscle.  It  presents  for  examination  six  surfaces, 
three  articular  and  three  non-articular.  The  non-articular  surfaces 
are  the  superior,  which  is  slightly  convex,  and  assists  in  forming 
the  dorsum  of  the  foot ;  the  inferior,  marked  by  a  prominent  ridge 
and  a  deep  groove,  for  the  tendon  of  the  peroneus  longus  ;  and  an 
external,  the  smallest  of  the  whole,  and  deeply  notched  by  the  com- 
mencement of  the  peroneal  groove.  The  articular  surfaces  are  the 
posterior,  which  is  of  large  size,  and  concavo-convex,  to  articulate 


METATARSAL    BONES. 


97 


Fig.  38/ 


with  the  OS  calcis  ;  anterior,  of  smaller  size,  divided  by  a  ridge 
into  two  facets,  for  the  fourth  and  fifth  metatarsal  bones  ;  and 
internal,  a  small  oval  articular  facet,  upon  a  large  and  quadran- 
gular surface,  for  the  external  cuneiform  bone. 

If  the  bone  be  held  so  that  the  plantar  surface,  with  the  peroneal 
groove,  look  downwards,  and  the  largest  articular  surface  back- 
wards, the  small  non-articular  surface,  marked  by  the  deep  notch, 
will  point  to  the  side  corresponding  with  the  foot  to  which  the  bone 
belongs. 

Articulations. — ^With  four  bones  ;  os  calcis,  external  cuneiform, 
and  fourth  and  fifth  metatarsal  bones. 

Attachment  of  Muscles. — To  three;  the  flexor  brevis  pollicis, 
adductor  pollicis,  and  flexor  brevis  minimi  digiti. 

Upon  a  consideration  of  the  tarsus  it  will  be  observed,  that  each 
bone  articulates  with  four  adjoining  bones,  with  the  exception  of 
the  OS  calcis,  which  articulates  with  two,  and  the  external  cunei- 
form with  six. 

Developement. — By  a  single  centre  for  each  bone,  with  the  ex- 
ception of  the  OS  calcis,  which  has  two  centres  of  ossification ;  the 
second  centre  makes  its  appearance  at  about  the  ninth  year,  and  is 
not  united  with  the  preceding  until  the  fifteenth. 

The  Metatarsal  Bones,  five  in  number, 
are  long  bones,  and  divisible  therefore  into  a 
shaft  and  two  extremities.  The  shaft  is  pris- 
moid,  and  compressed  from  side  to  side ;  the 
posterior  extremity,  or  base,  is  square-shaped, 
to  articulate  with  the  tarsal  boijes  and  with 
each  other;  and  the  anterior  extremity  pre- 
sents a  rounded  head,  circumscribed  by  a 
neck,  to  articulate  with  the  first  row  of  pha- 
langes. 

Peculiar  Metatarsal  Bones. — The  first  is 
shorter  and  larger  than  the  rest,  forming  the 
inner  border  of  the  foot;  its  posterior  extre- 
mity presents  only  one  articular  surface  on 
the  side,  and  an  oval  rough  surface  upon  a 
prominent  process  beneath,  for  the  insertion  of 
the  tendon  of  the  peroneus  longus.  The  an- 
terior extremity  has,  upon  its  plantar  surface, 
two  grooved  facets,  for  sesamoid  bones. 

The  second  is  the  longest  and  larg-est  of  the 
remaining  metatarsal  bones ;  it  presents  at  its 
base  three  articular  facets,  for  the  three  cunei- 

*  The  sole  of  the  left  foot.  1.  The  inner  tuberosity  of  the  os  calcis.  2.  The  outer 
tuberosity.  3.  The  groove  for  the  tendon  of  the  flexor  longus  digitorum.  4.  The 
rounded  head  of  the  astragalus.  5.  The  scaphoid  bone.  6.  Its  tuberosity.  7.  The 
internal  cuneiform  bone ;  its  broad  extremity.  8.  The  middle  cuneiform  bone.  9. 
The  external  cuneiform  bone.  10,  11.  The  cuboid  bone.  II.  Refers  to  the  groove  for 
the  tendon  of  the  peroneus  longus.  12,  12.  The  metatarsal  bones.  13,  13.  The  first 
phalanges.  14,14.  The  second  phalanges  of  the  four  lesser  toes.  15,15.  The  third, 
or  ungual  phalanges  of  the  four  lesser  toes.     16.  The  last  phalanx  of  the  great  toe. 

13 


98  PHALANGES. 

form  bones ;  a  large  oval  facet,  but  often  no  articular  surface,  on 
its  inner  side,  to  articulate  with  the  metatarsal  bone  of  the  great 
toe,  and  two  externally  for  the  metatarsal  bone. 

The  third  may  be  known  by  two  facets  upon  the  outer  side  of  its 
base,  corresponding  with  the  second,  and  may  be  distinguished  by 
its  smaller  size. 

The  fourth  may  be  distinguished  by  its  smaller  size,  and  by 
having  a  single  articular  surface  on  each  side  of  the  base. 

The  fifth  is  recognised  by  its  broad  base,  and  by  the  absence  of 
articular  surface  upon  its  outer  side. 

Developement. — Each  bone  by  two  centres ;  one  for  the  body  and 
one  for  the  digital  extremity  in  the  four  outer  metatarsal  bones ;  and 
one  for  the  body,  the  other  for  the  base  in  the  metatarsal  bone  of 
the  great  toe. 

Jlrticulations. — With  the  tarsal  bones  by  one  extremity,  and  with 
the  first  row  of  phalanges  by  the  other.  The  number  of  tarsal 
bones  with  which  each  metatarsal  articulates  from  within  outwards, 
is  the  same  as  between  the  metacarpus  and  carpus, — one  for  the 
first,  three  for  the  second,  one  for  the  third,  two  for  the  fourth,  and 
one  for  the  fifth ;  forming  the  cipher  13121. 

Attachment  of  Muscles. — To  fourteen;  to  the  first,  the  peroneus 
longus  and  first  dorsal  interosseous  muscle ;  to  the  second,  two  dor- 
sal interossei  and  transversus  pedis ;  to  the  third,  two  dorsal  and 
one  plantar  interosseous,  adductor  pollicis  and  transversus  pedis ;  to 
the  fourth,  two  dorsal  and  one  plantar  interosseous  and  adductor 
poUicis;  to  the  fifth,  one  dorsal  and  one  plantar  interosseous,  pero- 
neus brevis,  peroneus  tertius,  abdjactor  minimi  digiti,  flexor  brevis 
minimi  digiti,  and  transversus  pedis. 

Phalanges. — There  are  two  phalanges  in  the  great  toe,  and  three 
in  the  other  toes,  as  in  the  hand.  They  are  long  bones,  divisible 
into  a  central  portion  and  extremities. 

The  phalanges  of  the  first  row  are  convex  above,  concave  upon 
the  under  surface,  and  compressed  from  side  to  side.  The  posterior 
extremity  has  a  single  concave  articular  surface,  for  the  head  of  the 
metatarsal  bone;  and  the  anterior  extremity,  a  pulley-like  surface, 
for  the  second  phalanx. 

The  second  'phalanges  are  short  and  diminutive,  but  somewhat 
broader  than  the  first  row. 

The  third,  or  ungual  phalanges,  including  the  second  phalanx  of 
the  great  toe,  are  flattened  from  above  downwards,  and  spread  out 
laterally  at  the  base,  to  articulate  with  the  second  row,  and,  at  the 
opposite  extremity,  to  support  the  nail  and  the  rounded  extremity  of 
the  toe. 

Developement. — By  tivo  centres;  one  for  the  body  and  one  for  the 
metacarpal  extremity. 

Jlrticulations. — The  first  row  with  the  metatarsal  bones  and  second 
phalanges ;  the  second,  of  the  great  toe  with  the  first  phalanx,  and 
of  the  other  toes  with  the  first  and  third  phalanges ;  and  the  third, 
with  the  second  row. 


SESAMOID  BONES.  99 

Attachment  of  Muscles. — To  ticenty-tliree ;  to  the  first  p/ialanges ; 
great  toe,  the  innei-most  tendon  of  the  extensor  brevis  digitorum,  ab- 
ductor poUicis,  adductor  polUcis,  flexor  brevis  polhcis,  and  transver- 
sus  pedis ;  second  toe,  first  dorsal  and  first  palmar  interosseous  and 
lumbricalis ;  third  toe,  second  dorsal  and  second  palmar  interosseous 
and  lumbricalis;  fourth  toe,  third  dorsal  and  third  palmar  interos- 
seous and  lumbricahs ;  ffth  toe,  fourth  dorsal  interosseous,  abductor 
minimi  digiti,  flexor  brevis  minimi  digiti,  and  lumbricahs.  Second 
phalanges ;  great  toe,  extensor  longus  pollicis,  and  flexor  longus  pol- 
licis ;  other  toes,  one  shp  of  the  common  tendon  of  the  extensor  lon- 
gus digitorum,  and  extensor  brevis  digitorum,  and  flexor  brevis  digi- 
torum. Third  phalanges ;  two  slips  of  the  common  tendon  of  the 
extensor  longus  and  extensor  brevis  digitorum,  and  the  flexor  longus 
digitorum. 

Sesamoid  Bones. — These  are  small  osseous  masses,  developed  in 
those  tendons  which  exert  a  certain  degree  of  force  upon  the  sur- 
face over  which  they  glide,  or  where,  by  continued  pressure  and 
friction,  the  tendon  would  become  a  source  of  irritation  to  neigh- 
bouring parts,  as  to  joints.  The  best  example  of  a  sesamoid  bone  is 
the  patella,  developed  in  the  common  tendon  of  the  quadriceps  ex- 
tensor, and  resting  upon  the  front  of  the  knee-joint.  Besides  the  pa- 
tella, there  are  four  pairs  of  sesamoid  bones  included  in  the  number 
of  pieces  which  compose  the  skeleton,  two  upon  the  metacarpo- 
phalangeal articulation  of  each  thumb,  and  existing  in  the  tendons  of 
insertion  of  the  flexor  brevis  pollicis,  and  two  upon  the  correspond- 
ing joint  in  the  foot,  in  the  tendons  of  the  muscles  inserted  into  the 
base  of  the  first  phalanx.  In  addition  to  these  there  is  often  a  sesa- 
moid bone  upon  the  metacai^o-phalangeal  joint  of  the  little  finger, 
and  upon  the  corresponding  joint  in  the  foot,  in  the  tendons  inserted 
into  the  base  of  the  first  phalanx ;  there  is  one  also  in  the  tendon  of 
the  peroneus  longus  muscle,  where  it  glides  through  the  groove  in 
the  cuboid  bone  ;  sometimes  in  the  tendons,  as  they  wind  around  the 
inner  and  outer  malleolus ;  in  the  psoas  and  iliacus,  where  they  glide 
over  the  body  of  the  os  pubis ;  and  in  the  external  head  of  the  gas- 
trocnemius. 

The  bones  of  the  tympanum,  belonging  to  the  apparatus  of  hear- 
ing, will  be  described  with  the  anatomy  of  the  ear. 


CHAPTER      II 


ON  THE  LIGAMENTS. 


The  bones  are  variously  connected  with  each  other  in  the  con- 
struction of  the  skeleton,  and  the  connexion  between  any  two  bones 
constitutes  a  joint  or  articulation.  If  the  joint  be  immovable,  the 
surfaces  of  the  bones  are  applied  in  direct  contact ;  but  if  motion 
be  intended,  the  opposing  surfaces  are  expanded,  and  coated  by  an 
elastic  substance,  named  cartilage  ;  a  fluid  secreted  by  a  membrane 
closed  on  all  sides  lubricates  their  surface,  and  they  are  firmly  held 
together  by  means  of  short  bands  of  glistening  fibres,  which  are 
called  ligaments  (ligare,  to  bind).  The  study  of  hgaments  is  named 
syndesmology  (tfOv  together,  Ssdiiog,  bond),  which,  with  the  anatomy 
of  the  articulations,  forms  the  subject  of  the  present  chapter. 

The  forms  of  articulation  met  with  in  the  human  frame  may  be 
considered  under  three  classes  : — Synarthrosis,  Amphi-arthrosis  and 
Diarthrosis. 

Synarthrosis  (tfuv,  a^6^u(fig  articulation)  is  expressive  of  the  fixed 
form  of  joint  in  which  the  bones  are  immovably  connected  with 
each  other."  The  kinds  of  synarthrosis  are  four  in  number.  1. 
Sutura.  2.  Harmonia.  3.  Schindylesis.  4.  Gomphosis.  The  cha- 
racters of  the  three  first  have  been  sufficiently  explained  in  the  pre- 
ceding chapter,  p.  54.  It  is  here  only  necessary  to  state  that  in  the 
construction  of  sutures,  the  substance  of  the  bones  is  not  in  imme- 
diate contact,  but  it  is  separated  by  a  layer  of  membrane  which  is 
continuous  externally  with  the  pericranium  and  internally  with  the 
dura  mater.  It  is  the  latter  connexion  which  gives  rise  to  the  great 
difficulty  sometimes  experienced  in  tearing  the  calvarium  from  the 
dura  mater.  Cruveilhier  describes  this  interposed  membrane  as  the 
sutural  cartilage  :  I  never  saw  any  structure  in  the  sutures,  which 
could  be  regarded  as  cartilage,  and  the  history  of  the  formation  of 
the  cranial  bones  would  seem  to  point  to  a  diflferent  explanation. 
The  fourth,  Gomphosis  (70^905,  a  nail)  is  expressive  of  the  insertion 
of  one  bone  into  another,  in  the  same  manner  that  a  nail  is  fixed 
into  a  board ;  this  is  illustrated  in  the  articulation  of  the  teeth  with  the 
alveoli  of  the  maxillary  bones. 

Amphi-arthrosis  (a|X(pi'  both,  a^^^uidig)  is  a  joint  intermediate  in 
aptitude  for  motion  between  the  immovable  synarthrosis  and  the 
movable  diarthrosis.  It  is  constituted  by  the  approximation  of  sur- 
faces partly  coated  with  cartilage  lined  by  synovial  membrane,  and 
partly  connected  by  the  interosseous  ligaments,  or  by  the  interven- 


ARTICULATIONS MOVEMENTS.  101 

tion  of  an  elastic  fibro-cartilage  which  adheres  to  the  ends  of  both 
bones.  Examples  of  this  articulation  are  seen  in  the  union  between 
the  bodies  of  the  vertebrae,  of  the  sacrum  with  the  coccyx,  of  the 
two  first  pieces  of  the  sternum,  the  sacro-iliac  and  pubic  sym- 
physes (tfuv,  cpusiv  to  grow  together),  and  according  to  some,  of  the 
necks  of  the  ribs,  with  the  transverse  processes. 

DiARTHROsis  {5m  through,  a^^gwCij)  is  the  movable  articulation, 
which  constitutes  by  far  the  greater  number  of  the  joints  of  the 
body.  The  degree  of  motion  in  this  class  has  given  rise  to  a  sub- 
division into  three  genera,  Arthrodia,  Ginglymus,  and  Enarthrosis. 

Arthrodia  is  the  movable  joint  in  which  the  extent  of  motion  is 
slight  and  limited,  as  in  the  articulation  of  the  clavicle,  of  the  ribs, 
articular  processes  of  the  vertebrse,  axis  with  the  atlas,  radius  with 
the  ulna,  fibula  with  the  tibia,  carpal  and  metacarpal,  tarsal  and 
metatarsal  bones. 

Ginglymus  (yiyyXufxoff,  a  hinge)  or  hinge-joint,  is  the  movement  of 
bones  upon  each  other  in  two  directions  only,  viz.  forwards  and 
backwards ;  but  the  degree  of  motion  may  be  very  considerable. 
The  instances  of  this  form  of  joint  are  numerous  ;  they  comprehend 
the  elbow,  wrist,  metacarpo-phalangeal  and  phalangeal  joints  in  the 
upper  extremity ;  and  the  knee,  ankle,  metatarso-phalangeal  and 
phalangeal  joints  in  the  lower  extremity.  The  lower  jaw  may  also 
be  admitted  into  this  category,  as  partaking  more  of  the  character 
of  the  hinge-joint  than  of  the  less  movable  arthrodia. 

The  form  of  the  ginglymoid  joint  is  somewhat  quadrilateral  and 
each  of  its  four  sides  is  provided  with  a  ligament,  which  is  named 
from  its  position,  anterior,  'posterior,  internal  or  external  lateral. 
The  lateral  ligaments  are  thick  and  strong,  and  are  the  chief  bond 
of  union  between  the  bones.  The  anterior  and  posterior  are  thin 
and  loose  in  order  to  permit  the  required  extent  of  movement. 

Enarthrosis  (sv  in,  a^^^wtfi?)  is  the  most  extensive  in  its  range  of 
motion  of  all  movable  joints.  From  the  manner  of  connexion  and 
form  of  the  bones  in  this  articulation,  it  is  called  the  ball  and  socket 
joint.  There  are  three  instances  in  the  body,  viz.  the  hip,  the 
shoulder,  and  the  articulation  of  the  metacarpal  bone  of  the  thumb 
with  the  trapezium. 

The  ball  and  socket  joint  has  a  circular  form  ;  and,  in  place  of 
the  four  distinct  Hgaments  of  the  ginglymus,  is  enclosed  in  a  bag  of 
ligamentous  membrane,  called  a  capsular  ligament. 

The  kinds  of  articulation  may  probably  be  conveyed  in  a  more 

satisfactory  manner  in  the  tabular  form,  thus, 

Examples. 

f  Sutura     ....     bones  of  the  skull. 

o        tu      •     1  Harmonia    .     .     .     superior  maxillary  bones, 
synarthrosis. <  o  u-   j  i    •  -^i        ^ 

•^  }  fechmdylesis      .     .     vomer  with  rostrum. 

l^Gomphosis  .     .     .     teeth  with  alveoli. 

Amphi-arthrosis     .     Bodies  of  the  vertebrse     .     Symphyses. 

C  Arthrodia     .     .     .     carpal  and  tarsal  bones. 

Diarthrosis.  \  Ginglymus  .     .     .     elbow,  wrist,  knee,  ankle. 

( Enarthrosis      .     .     hip,  shoulder. 


102  STEUCTURE  OF  JOINTS. 

The  motions  permitted  in  joints  may  be  referred  to  four  heads, 
viz.:  1.  Gliding.  2.  Angular  movement.  3.  Circumduction.  4. 
Rotation. 

r.  Gliding  is  the  simple  movement  of  one  articular  surface  upon 
another,  and  exists  to  a  greater  or  less  extent  in  all  the  joints.  In 
the  least  movable  joints,  as  in  the  carpus  and  tarsus,  this  is  the 
only  motion  which  is  permitted. 

2.  Angular  movement  may  be  performed  in  four  different  direc- 
tions, either  forwards  and  backwards,  as  in  flexion  and  extension ; 
or  inwards  and  outwards,  constituting  adduction  and  abduction. 
Flexion  and  extension  are  illustrated  in  the  ginglymoid  joint,  and 
exist  in  a  large  proportion  of  the  joints  of  the  body.  Adduction 
and  abduction  conjoined  with  flexion  and  extension,  are  met  with 
complete  only  in  the  most  movable  joints,  as  in  the  shoulder,  the 
hip,  and  the  thumb.  In  the  wrist  and  in  the  ankle  adduction  and 
abduction  are  only  partial. 

3.  Circumduction  can  be  performed  only  in  the  shoulder  and 
hip  joints ;  it  consists  in  the  slight  degree  of  motion  which  takes 
place  in  the  head  of  a  bone  against  its  articular  cavity,  while  the 
extremity  of  the  limb  is  made  to  describe  a  large  circle  upon  a 
plane  surface. 

4.  Rotation  is  the  movement  of  a  bone  upon  its  own  axis,  and  is 
illustrated  in  the  hip  and  shoulder,  or  better  in  the  rotation  of  the 
cup  of  the  radius,  against  the  rounded  articular  protuberance  of  the 
humerus.  Rotation  is  also  observed  in  the  movements  of  the  atlas 
upon  the  axis,  in  which  the  odontoid  process  serves  as  a  pivot  around 
which  the  atlas  turns. 

The  structures  entering  into  the  composition  of  a  joint  are  bone, 
cartilage,  fibro-cartilage,  ligament,  and  synovial  membrane. 

Cartilage  is  an  elastic  and  apparently  homogeneous  substance  of 
a  pearly  whiteness,  which  forms  the  thin  incrustation  upon  the 
articular  surfaces  of  bones.  Upon  convex  surfaces  it  is  thickest  in 
the  centre,  and  thin  towards  the  circumference,  and  presents  upon 
concave  surfaces  an  opposite  arrangement.  It  is  composed  of  a 
number  of  minute  fibres  placed  perpendicularly  to  the  surface, 
attached  by  one  extremity  to  the  bone,  and  forming  by  the  other  a 
smooth  plane,  covered  by  synovial  membrane. 

Fibro-cartilage,  as  expressed  in  its  name,  is  a  compound  struc- 
ture, consisting  in  the  combination  of  fibrous  and  cartilaginous  tis- 
sues in  variable  proportions.  It  is  found  in  joints  under  three  forms : — 
1.  Of  interarticular  fibro-cartilages.  2.  Of  fibro-cartilages  of  cir- 
cumference.    3.  Of  intervertebral  substance. 

The  interarticular  fibro-cartilages  (menisci,)  composed  chiefly  of 
cartilage,  are  found  in  the  articulations  of  the  lower  jaw,  sternal 
and  acromial  end  of  the  clavicle,  knee  and  wrist-joint.  The  trian- 
gular cartilage  of  the  wrist  is  not  admitted  by  Dr.  Todd*  among 
the  fibro-cartilages,  but  is  considered  by  him  to  be  merely  an  exten- 

*  Cyclopaedia  of  Anatomy  and  PJiysiolog-y :  article,  Articulation. 


STRUCTURE  OF  JOINTS.  103 

sion  of  the  cartilaginous  incrustation  of  the  inferior  extremity  of  the 
radius. 

The Jibro-cartilages  of  circumference  contain  a  large  proportion 
of  fibrous  tissue ;  they  are  situated  upon  the  margins  of  the  glenoid 
and  cotyloid  cavities,  and  serve  to  deepen  those  articulations,  and 
at  the  same  time  to  protect  the  edges  from  injurious  pressure. 

The  intervertebral  substance  is  composed  of  concentric  lamellae  of 
fibrous  structure,  surrounding,  tov^ards  the  centre,  a  soft  cartilagi- 
nous and  almost  pulpy  mass.  The  fibres  of  which  the  lamellae  are 
formed,  interlace  with  each  other  obliquely;  the  intervening  meshes 
being  filled  with  a  soft  cartilaginous  substance,  and  becoming  larger 
towards  the  central  pulp. 

Ligament  is  composed  of  numerous  straight  fibres  collected 
together,  and  arranged  into  short  bands  (fasciculi)  of  various 
breadth,  or  interwoven  so  as  to  form  a  broad  layer  w^hich  com- 
pletely surrounds  the  articular  extremities  of  the  bones,  and  consti- 
tutes a  capsular  hgament. 

All  the  ligaments  of  the  joints  consist  of  fibres  of  this  kind,  which 
are  white,  glistening  and  inelastic.  But  besides  these  there  are 
other  ligaments,  which  are  composed  of  yellow  elastic  tissue,  and 
serve  to  connect  parts  which  are  subject  to  frequent  and  conside- 
rable separation,  as  the  arches  of  the  vertebrae,  where  they  form 
the  ligamenta  subflava. 

The  synovial  membrane  is  a  thin  membranous  layer,  which  invests 
the  articular  cartilages  of  the  bones,  and  is  thence  reflected  upon 
the  surfaces  of  the  ligaments  which  surround  and  enter  into  the 
composition  of  a  joint.  It  resembles  the  serous  membranes  in  being 
a  shut  sac,  and  secretes  a  transparent  and  viscous  fluid,  which  is 
named  synovia.  Synovia  is  an  alkaline  secretion,  containing 
album„en,  which  is  coagulable  at  a  boiling  temperature.  The  con- 
tinuation of  this  membrane  over  the  surface  of  the  articular  carti- 
lage, a  much  agitated  question,  has  lately  been  decided  by  the  inte- 
resting discoveries  of  Henle,  who  has  ascertained  the  existence  of  an 
epithelium  upon  cartilage  identical  with  that  secreted  by  the  reflected 
portion  of  the  membrane.  In  some  of  the  joints  the  synovial  mem- 
brane is  pressed  into  the  articular  cavity  by  a  cushion  of  fat,  which 
serves  the  purpose  of  facilitating  the  movements  of  the  surfaces.  This 
mass  was  called  by  Havers  the  synovial  gland,  from  an  incorrect 
supposition  that  it  was  the  source  of  the  synovia.  It  is  found  in  the 
hip  and  in  the  knee-joint.  In  the  knee-joint,  moreover,  the  synovial 
membrane  forms  folds,  which  are  most  improperly  named  ligaments, 
— as  the  mucous  and  alar  ligaments, — the  two  latter  being  an 
appendage  to  the  cushion  of  fat.  Besides  the  synovial  membranes 
entering  into  the  composition  of  joints,  there  are  numerous  smaller 
sacs  of  a  similar  kind  interposed  between  surfaces  which  move 
upon  each  other  so  as  to  cause  friction ;  they  are  often  associated 
with  the  articulations.  These  are  the  hurscp,  mucosce ;  they  are 
shut  sacs,  analogous  in  structure  to  synovial  membranes,  and 
secreting  a  similar  synovial  fluid. 


104  LIGAMENTS  OF  THE  TRUNK. 


ARTICULATIONS. 

The  joints  may  be  arranged,  according  to  a  natural  division, 
into  those  of  the  trunk,  those  of  the  upper  extremity,  and  those  of 
the  lower  extremity. 

LiGAME\TS  OF  THE  Trunk. — The  articulatious  of  the  trunk  are 
divisible  into  nine  groups,  viz. — 

1 .  Of  the  vertebral  column. 

2.  Of  the  atlas  with  the  occipital  bone. 

3.  Of  the  axis,  with  the  occipital  bone. 

4.  Of  the  atlas,  with  the  axis. 

5.  Of  the  lower  jaw. 

6.  Of  the  ribs,  with  the  vertebras. 

7.  Of  the  ribs,  with  the  sternum,  and  with  each  other. 

8.  Of  the  vertebral  column,  with  the  pelvis. 

9.  Of  the  pelvis. 

1.  Articulation  of  the  Vertebral  Column. — The  ligaments  connect- 
ing together  the  different  pieces  of  the  vertebral  column,  admit  of 
the  same  arrangement  with  that  of  the  vertebras  themselves.  Thus 
the  ligaments 

Of  the  bodies  are  the —         Anterior  common  ligament. 

Posterior  common  ligament. 

Intervertebral  substance. 
Of  the  arches, —  Ligamenta  subflava. 

Of  the  articular  processes, — Capsular  ligaments. 

Synovial  membranes. 
Of  the  spinous  processes, —  Inter-spinous. 

Supra-spinous. 
Of  the  transverse  processes, — Inter-transverse. 

Bodies. — The  anterior  common  ligament  is  a  broad  and  riband- 
like band  of  ligamentous  fibres,  extending  along  the  front  surface  of 
the  vertebral  column,  from  the  axis  to  the  sacrum.  It  is  intimately 
connected  with  the  intervertebral  substances,  and  less  closely  with 
the  bodies  of  the  vertebras. 

The  anterior  common  ligament  is  thicker  in  the  dorsal  than  in 
the  cervical  and  lumbar  regions,  and  consists  of  a  median  and  two 
lateral  portions  separated  from  each  other  by  a  series  of  openings 
for  the  passage  of  vessels.  The  ligament  is  composed  of  fibres  of 
various  length  closely  interwoven  with  each  other ;  the  deeper  and 
shorter  crossing  the  intervertebral  substances  from  one  vertebra  to 
the  next;  and  the  superficial  and  longer  fibres  crossing  three  or 
four  vertebra:. 

Relations. — The  anterior  common  ligament  is  in  relation  by  its 
posterior  or  vertebral  surface,  with  the  intervertebral  substances,  the 


LIGAMENTS  OF  THE  VERTEBRAL  COLUMN. 


105 


'-^1^ 


bodies  of  the  vertebrae  and  with  the  vessels,  principally  veins, 
which  separate  its  central  from  its  lateral  portions.  By  its  ante- 
rior or  visceral  surface  it  is  in  relation  in  the  neck,  with  the  longus 
colli  muscles,  the  pharynx  and  the 
cEsophagus ;  in  the  thoracic  re- 
gion, with  the  aorta,  the  venae 
azygos,  and  thoracic  duct ;  and  in 
the  lumbar  region,  with  the  aorta, 
right  renal  artery,  right  lumbar 
arteries,  arteria  sacra  media,  vena 
cava  inferior,  left  lumbar  veins, 
receptaculum  chyli,  the  com- 
mencement of  the  thoracic  duct, 
and  the  tendons  of  the  lesser  mus- 
cle of  the  diaphragm  with  the 
fibres  of  which  the  ligamentous  fibres  interlace. 

The  posterior  common  ligament  lies  upon  the  posterior  surface  of 
the  bodies  of  the  vertebrae,  and  extends  from  the  axis  to  the  sacrum. 
It  is  broad  opposite  the  intervertebral  substances,  to  which  it  is 
closely  adherent ;  and  narrow  and  thick  over  the  bodies  of  the  ver- 
tebra, from  which  it  is  separated  by  the  veins  of  the  base  of  the 
vertebrae.  It  is  composed  like  the  anterior  ligament  of  shorter  and 
longer  fibres  which  are  disposed  in  a  similar  manner. 

Relations. — The  posterior  common  ligament  is  in  relation  by  its 
anterior  surface  with  the  intervertebral  substances,  the  bodies  of 
the  vertebrae,  and  with  the  venae  basis  vertebrae ;  and  by  its  poste- 
rior surface  with  the  dura  mater  of  the  spinal  cord,  some  loose 
cellular  tissue  and  numerous  small  veins  being  interposed. 

The  intervertebral  substance  is  a  lenticular  disc  of  fibro-cartilage, 
interposed  between  each  of  the  vertebrae  from  the  axis  to  the 
sacrum,  and  retaining  them  firmly  in  connexion  with  each  other. 
It  differs  in  thickness  in  different  parts  of  the  column,  and  varies  in 
depth  at  different  points  of  its  extent ;  thus,  it  is  thickest  in  the  lum- 
bar region,  deepest  in  front  in  the  cervical  and  lumbar  regions, 
and  behind  in  the  dorsal  region;  and  contributes,  in  a  great 
measure,  to  the  formation  of  the  natiu'al  curves  of  the  vertebral 
column. 

Arches. — The  ligamenta  suhflava  are  composed  of  yellow  elastic 
tissue,  and  are  situated  between  the  arches  of  the  vertebrae,  from  the 
axis  to  the  sacrum.  From  the  imbricated  position  of  the  laminae 
they  are  attached  to  the  posterior  surface  of  the  vertebra  below,  and 
to  the  anterior  surface  of  the  arch  of  the  vertebra  above,  and  are 
separated  from  each  other  at  the  middle  line  by  a  slight  fissure. 
They  counteract,  by  their  elasticity,  the  eflbrts  of  the  flexor  muscles 


*  The  anterior  ligaments  of  the  vertebrse,  and  ligaments  of  the  ribs.  1.  The  ante- 
rior common  ligament.  2.  The  anterior  costo-vertebral  or  stellate  ligament.  3.  The 
anterior  costo-transverse  ligament.  4.  The  interarticular  ligament  connecting  the 
head  of  the  rib  to  the  intervertebral  substance,  and  separating  the  two  synovial  mem- 
branes of  this  articulation. 

14 


106 


LIGAMENTS  OF  THE  VERTEBRAL  COLUMN. 


of  the  trunk ;  and  by  preserving  the  upright  position  of  the  spine, 
Umit  the  expenditure  of  muscular  force.  They  are  longer  in  the  cer- 
vical than  in  the  other  regions  of  the  spine,  and  are  thickest  in  the 
lumbar  region. 

Fig.  40* 


Relations. — The  ligamenta  subflava  are  in  relation  by  both  sur- 
faces with  the  meningo-rachidian  veins,  and  internally  they  are 
separated  from  the  dura  mater  of  the  spinal  cord  by  those  veins  and 
some  loose  cellular  tissue. 

Articular  Processes.' — The  ligaments  of  the  articular  processes 
of  the  vertebrae,  are  loose  synovial  capsules  which  surround  the 
articulating  surfaces.  They  are  protected  on  their  external  side  by 
a  thin  layer  of  ligamentous  fibres. 

Spinous  Processes. — The  inter-spinous  hgaments  are  thin  and 
membranous,  and  are  extended  between  the  spinous  processes  in  the 
dorsal  and  lumbar  regions.  They  are  thickest  in  the  latter  region; 
and  are  in  j^elation  with  the  multifidus  spinae  muscle  at  each  side. 

The  supraspinous  ligament  (fig.  49)  is  a  strong  and  inelastic 
fibrous  cord,  which  extends  from  the  apex  of  the  spinous  process  of 
the  last  cervical  vertebra  to  the  sacrum,  being  attached  to  each 
spinous  process  in  its  course ;  it  is  thickest  in  the  lumbar  region. 
The  continuation  of  this  ligament  upwards  to  the  tuberosity  of  the 
occipital  bone,  constitutes  the  rudimentary  ligamentum  nuchse  of 
man.  It  is  strengthened,  as  in  animals,  by  a  thin  slip  from  the 
spinous  process  of  each  of  the  cervical  vertebra). 

Transverse  Processes. — The  inter-transverse  ligaments  are  thin 


*  A  ])osl.nrior  view  of  the  bodies  of  three  dorsal  vcrtobrro,  connected  by  their  inter- 
vertcbr;il  substance  1,1.  The  lamina)  (2)  have  been  sawn  away  near  to  the  bodies  of 
the  vertebra-,  and  tlic  arches  and  processes  removed,  in  order  to  show  (3)  the  posterior 
common  lijrament.  A  part  of  one  of  the  opening's  in  tlie  posterior  surface  of  the  verte- 
bra, for  the  transmission  of  the  vena  basis  vertebra;,  is  seen  at  4,  by  the  side  of  the 
narrow  and  unattached  portion  of  the  lig-ament. 

t  An  internal  view  of  the  arches  of  the  vcrtebrfc.  To  obtain  this  view  the  laminse 
have  been  divided  tliroii;rh  their  pedicles.  1.  One  of  tlic  ligamenta  subflava.  2.  The 
capsular  ligament  of  one  side. 


LIGAMENTS  OF  THE  VERTEBRAL  COLUMN. 


107 


and  membranous ;  they  are  found  only  between  the  transverse  pro- 
cesses of  the  lower  dorsal  vertebrse. 

2.  Articulation  of  the  Atlas  loith  the  Occipital  bone. — The  ligaments 
of  this  articulation  are  seven  in  number. 

Two  anterior  occipito-atloid. 

Posterior  occipito-atloid. 

Lateral  occipito-atloid. 

Two  capsular. 
Of  the  two  anterior  ligaments  one  is  a  rounded  cord,  situated  in 
the  middle  line,  and  superficially  to  the  other.  It  is  attached  above, 
to  the  basilar  process  of  the  occipital  bone ;  and  below,  to  the  an- 
terior tubercle  of  the  atlas.  The  deeper  ligament  is  a  broad  mem- 
branous layer,  attached  above,  to  the  margin  of  the  occipital  fora- 
men; and  below,  to  the  whole  length  of  the  anterior  arch  of  the 
atlas.  It  is  in  relation  in  front  with  the  recti  antici  minores  and  be- 
hind with  the  dura  mater. 


Fig.  42.* 


Fig.  43.t 


The  posterior  ligament  is  extremely  thin  and  membranous;  it  is 
attached  above,  to  the  margin  of  the  occipital  foramen ;  and  below, 
to  the  posterior  arch  of  the  atlas.  It  is  closely  adherent  to  the  dura 
mater,  by  its  inner  surface ;  and  forms  a  ligamentous  arch  at  each 
side,  for  the  passage  of  the  vertebral  arteries  and  first  cervical  nerves. 
It  is  in  relation  posteriorly  with  the  recti  postici  minores. 

The  lateral  ligaments  are  strong  fasciculi  of  liijamentous  fibres. 


*  An  anterior  view  of  the  ligaments  connecting  the  atlas,  the  axis,  and  the  occipital 
bone.  A  transverse  section  has  been  carried  through  the  base  of  the  skull,  dividing 
the  basilar  process  of  the  occipital  bone  and  the  petrous  portions  of  the  temporal  bones. 
1.  The  anterior  round  occipito-atloid  ligament.  2,  2.  The  anterior  broad  occipito- 
atloid  ligament.  3.  The  commencement  of  the  anterior  common  ligament.  4.  The  an- 
terior atlo-axoid  ligament,  which  is  continuous  inferiorly  with  the  commencement  of 
the  anterior  common  ligament.  5.  One  of  the  atlo-axoid  capsular  ligaments ;  the  one 
on  the  opposite  side  (6)  has  been  removed,  to  show  the  approximated  surfices  of  the  ar- 
ticular process.  7.  One  of  the  occipito-atloid  capsular  ligaments.  The  most  external 
of  these  fibres  constitute  the  lateral  occipito-atloid  ligament. 

t  The  posterior  ligaments  of  the  occipito-atloid,  and  atlo-axoid  articulations.  1.  Tlie 
atlas.  2,  The  axis.  3.  The  posterior  ligament  of  the  occipito-atloid  articulation.  4,4. 
The  c.ipsular  and  lateral  ligaments  of  this  articulation.  5.  The  posterior  ligaments  of 
the  atlo-axoid  articulation.  6,6.  Its  capsular  ligaments.  7.  The  first  of  the  ligamenta 
subflava  passing  between  the  axis  and  the  third  cervical  vertebra.  8, 8.  Their  capsular 
ligaments. 


108 


LIGAMENTS  OF  THE  VERTEBRAL  COLUMN. 


attached  below,  to  the  base  of  the  transverse  process  of  the  atlas  at 
each  side,  and  above  to  the  transverse  process  of  the  occipital  bone. 
With  a  ligamentous  expansion  derived  from  the  vaginal  process  of 
the  temporal  bone,  these  ligaments  form  a  strong  sheath  around  the 
vessels  and  nerves  which  pass  through  the  carotid  and  jugular  fora- 
men. 

The  capsular  ligaments  are  the  thin  and  loose  ligamentous  cap- 
sules, which  surround  the  synovial  membranes  of  the  articulations, 
between  the  condyles  of  the  occipital  bone  and  the  superior  articular 
processes  of  the  atlas.  The  ligamentous  fibres  are  most  numerous 
upon  the  anterior  and  external  part  of  the  articulation. 

The  movements  taking  place  between  the  cranium  and  atlas,  are 
those  of  flexion  and  extension,  giving  rise  to  the  forward  nodding  of 
the  head.  When  this  motion  is  increased  to  any  extent  the  whole  of 
the  cervical  region  concurs  in  its  production. 

3.  Articulation  of  the  Axis  ivit/i  the  Occipital  bone. — The  ligaments 
of  this  articulation  are  three  in  number, — 

Occipito-axoid, 
Two  odontoid. 

The  occipito-axoid  ligament  (appa- 
ratus ligamentosus  colh)  is  a  broad 
band,  which  covers  in  the  odontoid 
process  and  its  ligaments.  It  is  at- 
tached below  to  the  body  of  the  axis, 
and  is  continuous  with  the  posterior 
common  ligament;  superiorly  it  is 
inserted  by  a  broad  expansion,  into 
the  basilar  groove  of  the  occipital 
bone.  It  is  firmly  connected  oppo- 
site the  body  of  the  axis,  with  the 
dura  mater.  It  is  sometimes  de- 
scribed as  consisting  of  a  central  and  two  lateral  portions ;  this  how- 
ever is  an  unnecessary  refinement. 

The  odontoid  ligaments  (alar)  are  two  short  and  thick  fasciculi  of 
fibres,  which  pass  outwards  from  the  apex  of  the  odontoid  process, 
to  the  sides  of  the  occipital  foramen  and  condyles.  A  third  and 
smaller  fasciculus  also  proceeds  from  the  apex  of  the  odontoid  pro- 
cess, to  the  anterior  margin  of  the  foramen  magnum.f 

These  ligaments  serve  to  limit  the  extent  to  which  rotation  of  the 
head  maybe  carried,  hence  they  are  termed  check  ligaments. 

4.  Articulation  of  the  Atlas  ivith  the  Axis. — The  ligaments  of  this 
articulation  dire  five  in  number: — 


Fig.  44.* 


*The  upper  part  of  the  vertebral  canal,  opened  from  behind  in  order  to  show  the 
occipito-axoid  lifjaincnt.  1.  The  basilar  portion  of  the  sphenoid  bone.  2.  Section  of 
the  occipital  bone.  3.  The  atlas,  its  posterior  arch  removed.  4.  The  axis,  the  posterior 
arch  also  removed.  5.  The  occipito-axoid  ligament,  rendered  prominent  at  its  middle 
by  the  projection  of  the  odontoid  process.  6.  Lateral  and  capsular  ligament  of  the  oc- 
cipito-atloid  articulation.  7.  Capsular  ligament  between  tlie  articulating  process  of  the 
atlas  and  axis. 

+  Called  middle  straight  ligament, — G. 


LIGAMENTS  OF  THE  VERTEBRAL  COLUMN. 


109 


Anterior  atlo-axoid. 
Posterior  atlo-axoid. 


Two  capsular. 

Transverse. 


Fig.  45.+ 


The  anterior  ligament  consists  of  ligamentous  fibres,  which  pass 
from  the  anterior  tubercle  and  arch  of  the  atlas  to  the  base  of  the 
odontoid  process  and  body  of  the  axis,  where  they  are  continuous 
with  the  commencement  of  the  anterior  common  ligament.* 

The  -posterior  ligament  is  a  thin  and  membranous  layer,  passing 
between  the  posterior  arch  of  the  atlas  and  the  lamiuce  of  the  axis. 

The  capsular  ligaments  surround 
the  articular  processes  of  the  atlas 
and  axis  ;  they  are  loose,  to  permit 
of  the  freedom  of  movement  which 
subsists  between  the  atlas  and  axis. 
The  hgamentous  fibres  are  most 
numerous  on  the  outer  and  anterior 
part  of  the  articulation,  and  the 
synovial  membrane  usually  commu- 
nicates with  the  synovial  cavity  be- 
tween the  transverse  ligament  and 
the  odontoid  process. 

The  transverse  ligament  is  a  strong  Hgamentous  band,  which 
arches  across  the  area  of  the  ring  of  the  atlas  from  a  rough  tubercle 
upon  the  inner  surface  of  one  articular  process  to  a  similar  tubercle 
on  the  other.  It  serves  to  retain  the  odontoid  process  of  the  axis 
in  connexion  with  the  anterior  arch  of  the  atlas.  As  it  crosses  the 
odontoid  process,  some  fibres  are  sent  downwards  to  be  attached  to 
the  body  of  the  axis,  and  others  pass  upwards  to  be  inserted  into 
the  basilar  process  of  the  occipital  bone  ;J  hence  the  hgament  has  a 
cross-like  appearance,  and  has  been  denominated  cruciform.  A 
synovial  membrane  is  situated  between  the  transverse  ligament  and 
the  odontoid  process ;  and  another  between  that  process  and  the 
inner  surface  of  the  anterior  arch  of  the  atlas. 

Actions. — It  is  the  peculiar  disposition  of  this  ligament  in  relation 
to  the  odontoid  process,  that  enables  the  atlas,  and  with  it  the  entire 
cranium,  to  rotate  upon  the  axis  ;  the  perfect  freedom  of  movement 
between  these  bones  being  ensured  by  the  two  synovial  membranes. 
The  lower  part  of  the  ring,  formed  by  the  transverse  ligament  with 
the  atlas,  is  smaller  than  the  upper,  while  the  summit  of  the  odontoid 
process  is  larger  than  its  base ;  so  that  the  process  is  still  retained  in 


*  Usually  considered  a  part  of  the  anterior  vertebral  ligament. — G. 

+  A  posterior  view  of  the  ligaments  connecting  the  atlas,  the  axis,  and  the  occipital 
bone.  The  posterior  part  of  the  occipital  bone  has  been  sawn  away,  and  the  arches  of 
the  atlas  and  axis  removed.  1.  The  superior  part  of  the  occipito-axoid  ligament, 
which  has  been  cut  away  in  order  to  show  the  ligaments  beneath.  2.  The  transverse 
ligament  of  the  atlas.  3,  4.  The  ascending  and  descending  slips  of  the  transverse  liga- 
ment,  which  have  obtained  for  it  the  title  of  cruciform  ligament.  5.  One  of  the  odon- 
toid ligaments.  6.  One  of  the  occipito-atloid  capsular  ligaments.  7.  One  of  the  atlo- 
axoid  capsular  ligaments. 

t  These  bands  are  called  the  appendices  of  the  transverse  ligament. — G. 


110 


LIGAMENTS  OF  THE  LOWER  JAW. 


its  position  by  the  transverse  ligament,  when  the  other  Hgaments  are 
cut  throuD-h.  The  extent  to  which  the  rotation  of  the  head  upon  the 
axis  can  be  carried  is  determined  by  the  odontoid  hgaments.  The 
odontoid  process  with  its  hgaments  is  covered  in  by  the  occipito- 
axoid  hgament. 

5.  Articulation  of  the  Lower  Jaw. — The  lower  jaw  has  properly 
but  one  ligament,  the  external  lateral;  the  ligaments  usually  described 
are  three  in  number;  to  which  may  be  added,  as  appertaining  to  the 
mechanism  of  the  joint,  an  interarticular  fibro-cartilage,  and  two 
synovial  membranes : — 

External  lateral, 
Internal  lateral, 
Capsular. 

Interarticular  fibro-cartilage, 

Two  synovial  membranes. 

The  external  lateral  ligament  is  a  short  and  thick  band  of  fibres, 
passing  obhquely  forwards  from  the  tubercle  of  the  zygoma,  to  the 

external  surface  of  the  neck  of  the 
Fig,  46.*  lower  jaw.     It  is  in  relation,  exter- 

nally with  the  integument  of  the 
face,  and  internally  with  the  syno- 
vial membranes  of  the  articulation, 
and  with  the  interarticular  fibro-car- 
tilage. The  external  lateral  ligament 
acts  conjointly  with  its  fellow  of  the 
opposite  side  of  the  head  in  the  move- 
ments of  the  jaw. 

The  internal  lateral  ligament  has 
no  connexion  with  the  articulation 
of  the  lower  jaw,  and  is  incorrectly 
named  in  relation  to  the  joint ;  it  is  a  thin  aponeurotic  expansion 
extending  from  the  extremity  of  the  spinous  process  of  the  sphenoid 
bone  to  the  margin  of  the  dental  foramen.  It  is  pierced  at  its  inser- 
tion, by  the  mylo-hyoidean  nerve. 

A  triano-ular  space  is  left  between  the  internal  lateral  ligament  and 
the  neck  of  the  jaw,  in  which  are  situated  the  internal  maxillary 
artery  and  auricular  nerve,  the  inferior  dental  artery  and  nerve,  and 
a  part  of  the  external  pterygoid  muscle ;  internally  it  is  in  relation 
with  the  internal  pterygoid. 

The  capsular  ligament  consists  of  a  few  irregular  ligamentous 
fibres,  which  pass  from  the  edge  of  the  glenoid  cavity  to  the  neck 
of  the  lower  jaw,  upon  the  inner  and  posterior  side  of  the  articula- 

»  An  external  view  of  Uie  articulation  of  the  lower  jaw,  1.  The  zygomatic  arch. 
2.  The  tubercle  of  the  zygoma.  3.  The  ramus  of  the  lower  jaw.  4.  The  mastoid 
portion  of  the  teitiijoral  bone.  5.  The  external  lateral  ligament.  6,  The  stylo-maxil- 
lary  ligament. 


LIGAMENTS  OP  THE  LOWER  JAW. 


Ill 


^m^ 


Fig.  48.+ 


tion.     These  fibres  scarcely  deserve  consideration  as  a  distinct 
ligament. 

The  interarticular  fihro- cartilage  is  a  thin  oval  plate,  thicker  at 
the  edges  than  in  the  centre,  and  placed  horizontally  between  the 
head  of    the   condyle   of    the 
lower  jaw  and  the  glenoid  ca-  Fig-  47.* 

vity.  It  is  connected  by  its 
outer  border  with  the  external 
lateral  ligament,  and  in  front 
receives  some  fibres  of  inser- 
tion of  the  external  pterygoid 
muscle.  Occasionally  it  is  in- 
complete in  the  centre.  It 
divides  the  joint  into  two  dis- 
tinct cavities,  the  one  being 
above  and  the  other  below  the 
cartilage. 

The  synovial  membranes  are  situated  the  one  above,  the  other 
below  the  fibro-cartilage,  the  former  being  the  larger  of  the  two. 
When  the  fibro-cartilage  is  perforate,  the  synovial  membranes  com- 
municate with  each  other. 

Besides  the  lower  jaw,  there  are 
several  other  joints  provided  with  a 
complete  interarticular  fibro-cartilage, 
and  consequently,  with  two  synovial 
membranes ;  they  are,  the  sterno-clavi- 
cular  articulation,  the  acromio-clavi- 
cular,  and  the  articulation  of  the  ulna 
with  the  cuneiform  hone. 

The  interarticular  fibro-cartilages 
of  the  knee-joint  are  partial,  and 
there  is  but  one  synovial  membrane. 

The  articulations  of  the  heads  of  the 
ribs  with  the  vertebra  have  two  syno- 
vial membranes,  separated  by  an  interarticular  ligament  without 
fibro-cartilage. 

Actions. — The  movements  of  the  lower  jaw  are  depression  by 

*  An  internal  view  of  the  articulation  of  the  lower  jaw.  1.  A  section  through  the 
petrous  portion  of  the  temporal  bone  and  spinous  process  of  the  sphenoid.  2.  An 
internal  view  of  the  ramus,  and  part  of  the  body  of  the  lower  jaw.  3.  The  internal 
portion  of  the  capsular  ligament.  4.  The  internal  lateral  ligament.  5.  A  small  interval 
at  its  insertion  through  which  the  mylo-hyoidean  nerve  passes,  6.  The  stylo-maxillary 
ligament,  a  process  of  the  deep  cervical  fascia. 

+  In  this  sketch  a  section  has  been  carried  through  the  joint,  in  order  to  show  the 
natural  position  of  the  interarticular  fibro-cartilage,  and  the  manner  in  which  it  is 
adapted  to  the  difference  of  form  of  the  articulating  surfaces.  1.  The  glenoid  fossa. 
2.  The  emincntia  articularis.  3.  The  interarticular  fibro-cartilage.  4.  The  superior 
synovial  cavity.  5.  The  inferior  synovial  cavity.  6.  An  interarticular  fibro-cartilage, 
removed  from  the  joint,  in  order  to  show  its  oval  and  concave  form;  it  is  seen  from 
below. 


112  LIGAMENTS  OF  THE  RIBS. 

which  the  mouth  is  opened ;  elevation,  by  which  it  is  closed;  a.  for- 
ward and  hachrard  movement,  and  a  movement  from  side  to  side. 

In  the  movement  of  depressioJi  the  interarticular  cartilage  glides 
forwar  dson  the  eminentia  articularis,  carrying  with  it  the  condyle. 
If  this  movement  be  carried  too  far,  the  superior  synovial  membrane 
is  ruptured,  and  dislocation  of  the  fibro-cartilage  with  its  condyle 
into  the  zygomatic  fossa  occurs.  In  elevation  the  fibro-cartilage 
and  condyle  are  returned  to  their  original  position.  The  forward 
and  hachoard  movement  is  a  gliding  of  the  fibro-cartilage  upon  the 
glenoid  articular  surface,  in  the  antero-posterior  direction  ;  and  the 
movement  from  side  to  side,  in  the  lateral  direction. 

6.  Articulation  of  the  Ribs  with  the  Vertehrce. — The  ligaments  of 
these  articulations  are  so  strong  as  to  render  dislocation  impossible, 
the  neck  of  the  rib  would  break  before  displacement  could  occur ; 
they  are  divisible  into  two  groups  : — 1.  Those  connecting  the  head 
of  the  rib  with  the  vertebrcs ;  and  2.  Those  connecting  the  neck  and 
tubercle  of  the  rib  with  the  transverse  processes.     They  are 

1st  Group. 

Anterior  costo-vertebral  or  stellate, 

Capsular, 

Interarticular  ligament, 

Two  synovial  membranes. 

2c?  Group. 

Anterior  costo-transverse. 
Middle  costo-transverse. 
Posterior  costo-transverse. 

The  anterior  costo-vertebral  or  stellate  ligament  (fig.  39)  consists 
of  three  short  bands  of  ligamentous  fibres  that  radiate  from  the 
anterior  part  of  the  head  of  the  rib.  The  superior  band  passes 
upwards,  and  is  attached  to  the  vertebra  above ;  the  middle  fasci- 
culus is  attached  to  the  intervertebral  substance ;  and  the  inferior, 
to  the  vertebra  below. 

In  the  first,  eleventh,  and  twelfth  ribs,  the  three  fasciculi  are 
attached  to  the  body  of  the  corresponding  vertebra. 

The  capsular  ligament  is  a  thin  layer  of  ligamentous  fibres  sur- 
rounding the  joint  in  the  interval  left  by  the  anterior  hgament;  it  is 
thickest  a})ove  and  below  the  articulation,  and  protects  the  synovial 
memjjrancs. 

The  interarticular  ligament  passes  between  the  sharp  crest  on  the 
head  of  the  rib  and  the  intervertebral  substance.  It  divides  the  joint 
into  two  cavities,  which  are  each  furnished  with  a  separate  synovial 
membrane.  The  first,  eleventh,  and  twelfth  ribs  have  no  interarticular 
ligament,  anrl  consequently  but  one  synovial  membrane. 

The  anterior  costo-transverse  ligament  is  a  broad  band  composed 


LIGAMENTS  OF  THE  RIBS. 


113 


Fig.  49  * 


of  several  fasciculi,  which  ascend  from  the  crest  upon  the  neck  of 
the  rib,  to  the  transverse  process  immediately  above.  This  liga- 
ment separates  the  anterior  from  the  posterior  branch  of  the  inter- 
costal nerves. 

The  middle  costo-transverse  ligament  is  a  very  strong  interosseous 
ligament,  passing  directly  betw^een  the  posterior  surface  of  the  neck 
of  the  rib,  and  the  transverse  process  against  which  it  rests. 

The  posterior  costo-transverse  ligament  is  a  small  but  strong  fasci- 
culus, passing  obliquely  from  the  tubercle  of  the  rib,  to  the  apex  of 
the  transverse  process.  The  articulation  between  the  tubercle  of  the 
rib  and  the  transverse  process  is  provided  with  a  small  synovial 
membrane. 

There  is  no  anterior  costo-transverse 
ligament  to  the  first  rib ;  and  only  rudi- 
mentary posterior  costo-transverse  to  the 
eleventh  and  twelfth  ribs. 

Actions. — The  movements  permitted  by 
the  articulations  of  the  ribs,  are  wptoards 
and  dowmvards,  and  slightly  forwards  and 
bachvards ;  the  movement  increasing  in 
extent  from  the  head  to  the  extremity  of 
the  rib.  The  forward  and  backward 
movement  is  very  trifling  in  the  seven 
superior,  but  greater  in  the  inferior  ribs ; 
the  eleventh  and  twelfth  are  very  mo- 
vable. 

7.  Articulation  of  the  Ribs  with  the  Sternum,  and  loith  each  other. 
— The  ligaments  of  the  costo-sternal  articulations  are, 

Anterior  costo  sternal. 
Posterior  costo-sternal, 
Superior  costo-sternal, 
Inferior  costo-sternal. 
Synovial  membranes. 

The  anterior  costo-sternal  ligament  is  a  thin  band  of  ligamentous 
fibres,  that  passes  in  a  radiated  direction  from  the  extremity  of  the 
costal  cartilage  to  the  anterior  surface  of  the  sternum,  and  inter- 
mingles its  fibres  with  those  of  the  ligament  of  the  opposite  side, 
and  with  the  tendinous  fibres  of  origin  of  the  pectoralis  major 
muscle. 

The  -posterior  costo-sternal  ligament  is  much  smaller  than  the  an- 
terior, and  consists  of  only  a  thin  fasciculus  of  fibres  situated  on  the 
posterior  surface  of  the  articulation. 

*  A  posterior  view  of  a  part  of  the  thoracic  portion  of  the  vertebral  column,  showing 
the  ligaments  connecting  the  vertebrte  with  each  other  and  the  ribs  with  the  vertebrae. 
1.  The  supra-spinous  ligament.  2,  2.  The  ligamenta  subflava,  connecting  the  laminffi. 
3.  The  anterior  costo-transverse  ligament.  4.  The  posterior  costo-transverse  liga- 
ments. 

15 


114  LIGAMENTS  OF  THE  PELVIS. 

The  superior  and  inferior  costo-sternal  ligaments  are  narrow  fas- 
ciculi corresponding  with  the  breadth  of  the  cartilage,  and  connect- 
ing its  superior  and  inferior  border  "svith  the  side  of  the  sternum. 

The  synovial  membrane  is  absent  in  the  articulation  of  the  first 
rib,  its  cartilage  being  usually  continuous  with  the  sternum ;  that  of 
the  second  rib  has  an  inter- articular  Hgament,  with  two  synovial 
membranes. 

The  sixth  and  seventh  ribs  have  several  fasciculi  of  strong  liga- 
mentous fibres,  passing  from  the  extremity  of  their  cartilages  to  the 
anterior  surface  of  the  ensiform  cartilage,  which  they  are  intended 
to  support.     They  may  be  named  the  coslo-xypJwid  ligaments. 

The  sixth,  seventh,  and  eighth,  and  sometimes  the  fifth  and  the 
ninth  costal  cartilages,  have  articulations  with  each  other,  and  a 
perfect  synovial  membrane.  They  are  connected  by  ligamentous 
fibres  which  pass  from  one  cartilage  to  the  other,  external  and 
internal  ligaments. 

The  ninth  and  tenth  are  connected  at  their  extremities  by  liga- 
mentous fibres,  but  have  no  synovial  membranes. 

Actions. — The  movements  of  the  costo-sternal  articulations  are 
very  trifling;  they  are  limited  to  a  slight  sliding  motion.  The  first 
rib  is  the  least,  and  the  second  the  most  movable. 

8.  Articulation  of  the  Vertebral  Column  with  the  Pelvis. — The  last 
lumbar  vertebra  is  connected  with  the  sacrum  by  the  same  liga- 
ments with  which  the  various  vertebrae  are  connected  to  each  other ; 
viz.  the  anterior  and  posterior  common  ligaments,  intervertebral  sub- 
stance, ligamenta  subflava,  capsular  ligaments,  and  inter  and  supra- 
spinous ligaments. 

There  are  only  tim  proper  ligaments  connecting  the  vertebral 
column  with  the  pelvis;  these  are,  the 

Lumbo-sacral, 
Lumbo-iUac. 

The  lumbo-sacral  ligament  is  a  thick  triangular  fasciculus  of  liga- 
mentous fibres,  connected  above,  with  the  transverse  process  of  the 
last  lumbar  vertebra ;  and  below,  with  the  posterior  part  of  the 
upper  border  of  the  sacrum. 

The  lumbo-iliac  ligament  passes  from  the  apex  of  the  transverse 
process  of  the  last  lumbar  vertebra  to  that  part  of  tlie  crest  of  the 
ilium  which  surmounts  the  sacro-iliac  articulation.  It  is  triangu- 
lar in  form. 

9.  The  Articulations  of  the  Pelvis. — The  ligaments  belonging  to 
the  articulations  of  the  pelvis  are  divisible  into  four  groups: — 1. 
Those  connecting  the  sacrum  and  ilium;  2,  those  passing  between 
the  sacrum  and  ischium;  3,  between  the  sacrum  and  coccyx;  and  4, 
between  the  two  pubic  bones. 

1st,  Between  the  sacrum  and  ilium. 

Sacro-iliac  anterior, 
Sacro-iliac  posterior. 


LIGAMENTS  OF  THE  PELVIS. 


115 


Fig.  50* 


2nd,  Between  the  sacrum  and  ischium. 
Sacro-ischiatic  anterior  (short), 
Sacro-ischiatic  posterior  (long). 

3rd,  Between  the  sacrum  and  coccyx. 
Sacro-coccygean  anterior, 
Sacro-coccygean  posterior. 

4th,  Between  the  ossa  pubis. 
Anterior  pubic, 
Posterior  pubic, 
Superior  pubic, 
Sub-pubic, 
Interosseous  fibro-cartilage. 

1.  Between  the  Sacrum  and  Ilium. — The  anterior  sacro-iliac  liga- 
ment consists  of  numerous  short  Hgamentous  fibres,  passing  from 
bone  to  bone  on  the  anterior  surface  of  the  joint. 

The  posterior  sacro-iliac  or  interos- 
seous ligament]  is  composed  of  nume- 
rous strong  fasciculi  of  Hgamentous 
fibres,  which  pass  horizontally  be- 
tween the  rough  surfaces,  in  the  pos- 
terior half  of  the  sacro-iliac  articula- 
tion, and  constitute  the  principal  I.. 
bond  of  connexion  between  the  sa- 
crum and  the  ilium.  One  fasciculus 
of  this  ligament,  longer  and  larger 
than  the  rest,  is  distinguished,  from 
its  direction,  by  the  name  of  the  ob- 
lique sacro-iliac  ligament.  It  is  at 
tached  by  one  extremity,  to  the  pos- 
terior superior  spine  of  the  ilium ; 
and  by  the  other,  to  the  third  trans- 
verse tubercle  on  the  posterior  sur- 
face of  the  sacrum. 

The  surfaces  of  the  two  bones 
forming  the  sacro-iliac  articulation,  are  partly  covered  with  carti- 
lage, and  partly  rough  and  connected  by  the  interosseous  ligament. 
The  anterior  or  auricular  half  is  coated  with  cartilage,  which  is 
thicker  on  the  sacrum  than  on  the  ilium.  The  surface  of  the  car- 
tilage is  irregular,  and  provided  with  a  very  delicate  synovial  mem- 

*The  lig^aments  of  the  pelvis  and  hip-joint.  1.  The  lower  part  of  the  anterior  com- 
mon ligament  of  the  vertebrae,  extending  downwards  over  the  front  of  tlie  sacrum.  2. 
The  himbo-sacral  ligament.  3.  The  lumbo-iliac  ligament.  4.  The  anterior  sacro-iliac 
ligaments.  5.  The  obturator  membrane.  6.  Poupart's  ligament.  7.  Gimbernat's 
ligament.  8.  The  capsular  ligament  of  the  hip-joint.  9.  Tlie  ilio-fcmoral  or  acces- 
sory ligament. 

t  This  includes  Horner's  sacro-spinous  ligament. — G. 


116  LIGAMENTS  OF  THE  PELVIS. 

brane,  which  cannot  be  demonstrated  in  the  adult ;  but  is  apparent 
in  the  young  subject,  and  in  the  female  during  pregnancy. 

2.  Between  the  Sacrum  and  Ischium. — The  anterior  or  lesser  sacro- 
ischiatic  ligament  is  thin,  and  triangular  in  form;  it  is  attached  by 

its  apex  to   the  spine  of  the 
Fig.  51  *  •      ischium ;  and  by  its  broad  ex- 

tremity to  the  side  of  the  sa- 
crum and  coccyx,  interlacing 
its  fibres  with  the  succeeding. 
The  anterior  sacro-ischiatic 
ligament  is  in  relation  in  front, 
with  the  coccygeus  muscle, 
and  behind  with  the  posterior 
ligament,  with  which  its  fibres 
are  intermingled.  By  its  up- 
per border  it  forms  a  part  of 
the  lower  boundary  of  the 
great  sacro-ischiatic  foramen, 
and  by  the  lower  a  part  of  the 
lesser  sacro-ischiatic  foramen. 
The  posterior  or  greater  sa- 
cro-ischiatic ligament,  consi- 
derably larger,  thicker,  and 
more  posterior  than  the  pre- 
ceding, is  narrower  in  the  middle  than  at  each  extremity.  It  is 
attached  by  its  smaller  end,  to  the  inner  margin  of  the  tuberosity 
and  ramus  of  the  ischium,  where  it  forms  a  falciform  process,  which 
protects  the  internal  pudic  artery,  and  is  continuous  with  the  ob- 
turator fascia.  By  its  larger  extremity  it  is  inserted  into  the  side  of 
the  coccyx,  sacrum,  and  posterior  inferior  spine  of  the  ilium. 

The  posterior  sacro-ischiatic  ligament  is  in  relation  in  front  with 
the  anterior  ligament,  and  behind  with  the  gluteus  maximus,  to  some 
of  the  fibres  of  which  it  gives  origin.  By  its  superior  border  it 
forms  part  of  the  lesser  ischiatic  foramen,  and  by  its  lower  border, 
a  part  of  the  boundary  of  the  perineum.  It  is  pierced  by  the  coc- 
cygeal branch  of  the  ischiatic  artery.  The  two  ligaments  convert 
the  sacro-ischiatic  notches  into  foramina. 

3.  Between  the  Sacrum  and  Coccyx. — The  anterior  sacro-coccy- 
geal  ligament  is  a  thin  fasciculus  passing  from  the  anterior  surface 
of  the  sacrum  to  the  front  of  the  coccyx. 

The  posterior  sacro-coccygean  ligament  is  a  thick  ligamentous  layer, 

*  Ligaments  of  the  pelvis  and  hip-joint.  The  view  is  taken  from  the  side.  1.  The 
oblique  sacro-iliac  ligament.  The  other  fasciculi  of  the  posterior  sacro-iliae  ligaments 
arc  not  seen  in  this  view  of  the  pelvis.  2.  Tlic  posterior  sacro-ischiatic  ligament.  3. 
The  anterior  sacro-ischiatic  ligament.  4.  The  great  sacro-iscliiatie  foramen.  5.  The 
lesser  sacro-ischiatie  foramen.  6.  The  cotyloid  ligament  of  the  acetabulum.  7.  The 
ligamcntum  teres.  8.  The  cut  edge  of  the  capsular  ligament,  showing  its  extent  pos- 
teriorly as  compared  with  its  anterior  attachment.  9.  The  obturator  membrane  only 
partly  seen. 


LIGAMENTS  OF  THE  PELVIS,  117 

which  completes  the  lower  part  of  the  sacral  canal,  and  connects 
the  sacrum  with  the  coccyx  posteriorly,  extending  as  far  as  the  apex 
of  the  latter  bone. 

Between  the  two  bones  is  a  thin  disc  of  a  soft  intervertebral  sub- 
stance. In  females  there  is  frequently  a  small  synovial  membrane. 
This  articulation  admits  of  a  certain  degree  of  movement  backwards 
during  parturition. 

The  ligaments  connecting  the  different  pieces  of  the  coccyx  con- 
sist of  a  few  scattered  anterior  and  'posterior  fibres,  and  a  thin  disc 
of  intervertebral  substance ;  they  exist  only  in  the  young  subject,  in 
the  adult  the  pieces  become  ossified. 

4.  Between  the  Ossa  Pubis. — The  anterior  pubic  ligament  is  com- 
posed of  ligamentous  fibres,  which  pass  obUquely  across  the  union  of 
the  two  bones  from  side  to  side,  and  form  an  interlacement  in  front  of 
the  symphysis. 

The  posterior  pubic  ligament  consists  of  a  few  irregular  fibres 
uniting  the  pubic  bones  posteriorly. 

The  superior  pubic  ligament  is  a  thick  band  of  fibres  connecting 
the  angles  of  the  pubic  bones  superiorly,  and  filling  the  inequalities 
upon  the  surface  of  the  bones. 

The  sub-pubic  ligament  is  a  thick  arch  of  fibres  connecting  the 
two  bones  inferiorly,  and  forming  the  upper  boundary  of  the  pubic 
arch. 

The  interosseous  fibro-cartilage  unites  the  two  surfaces  of  the  pubic 
bones,  in  the  same  manner  that  the  intervertebral  substance  con- 
nects the  bodies  of  the  vertebra.  It  resembles  the  intervertebral 
substance  also  in  being  composed  of  oblique  fibres  disposed  in  con- 
centric layers,  which  are  more  dense  towards  the  surface  than  near 
the  centre.  It  is  broad  in  front,  and  narrow  behind.  A  thin  syno- 
vial membrane  is  sometimes  found  in  the  posterior  half  of  the  articu- 
lation. 

This  articulation  becomes  movable  towards  the  latter  term  of  preg- 
nancy, and  admits  of  a  slight  degree  of  separation  of  its  surfaces. 

The  obturator  ligament  or  membrane  is  not  a  ligament  of  articula- 
tion, but  simply  a  tendino-fibrous  membrane  stretched  across  the 
obturator  foramen.  It  gives  attachment  by  its  surfaces,  to  the  two 
obturator  muscles  ;  and  leaves  a  space  in  the  upper  part  of  the  fora- 
men, for  the  passage  of  the  obturator  vessels  and  nerve. 

The  numerous  vacuities  in  the  walls  of  the  pelvis,  and  their  clo- 
sure by  ligamentous  structures,  as  in  the  case  of  the  sacro-ischiatic 
fissures  and  obturator  foramina,  serve  to  diminish  very  materially 
the  pressure  of  the  soft  parts  during  the  passage  of  the  head  of  the 
foetus  through  the  pelvis  in  parturition. 


LIGAMENTS  OF  THE  UPPER  EXTREMITY. 

The  Ligaments  of  the  upper  extremity  may  be  arranged  in  the 
order  of  the  articulation  between  the  different  hones ;  they  are,  tlie 


118  STERNO-CLAVICULAR  LIGAMENTS. 

1.  Sterno-clavicular  articulation. 

2.  Scapulo-cla\'icular  articulation. 

3.  Ligaments  of  the  scapula. 

4.  Shoulder  joint. 

5.  Elbow  joint. 

6.  Radio-ulnar  articulation. 

7.  Wrist  joint. 

8.  Articulation  between  the  carpal  bones. 

9.  Carpo-metacarpal  articulation. 

10.  Metacarpo-phalangeal  articulation. 

11.  Articulation  of  the  phalanges. 

I.  Sterno-clavicular  Articulation. — The  sterno-clavicular  is  an 
arthrodial  articulation ;  its  ligaments  are, 

Anterior  sterno-clavicular, 
Posterior  sterno-clavicular, 
Inter-clavicular, 
Costo-clavicular  {rhomboid), 

Interarticular  fibro-cartilage, 

Two  synovial  membranes. 

The  anterior  sterno-clavicular  ligament  is  a  broad  ligamentous 
layer,  extending  obliquely  downwards  and  forwards,  and  covering 
the  anterior  aspect  of  the  articulation.  This  ligament  is  in  relation 
by  its  anterior  surface  with  the  integument  and  with  the  sternal 
origin  of  the  sterno-mastoid  muscle  ;  and  behind  with  the  interarti- 
cular fibro-cartilage  and  synovial  membranes. 

The  -posterior  sterno-clavicular  ligament  is  a  broad  fasciculus, 
covering  the  posterior  surface  of  the  articulation.  It  is  in  relation 
by  its  anterior  surface  with  the  interarticular  fibro-cartilage  and 
synovial  membranes,  and  behind  with  the  sterno-hyoid  muscle. 

The  two  ligaments  are  continuous  at  the  upper  and  lower  part 
of  the  articulation,  so  as  to  form  a  complete  capsule  around  the 
joint. 

The  inter-clavicular  ligament  is  a  cord-like  band  which  crosses 
from  the  extremity  of  one  clavicle  to  the  other,  and  is  closely  con- 
nected with  the  upper  border  of  the  sternum.  It  is  separated  by 
cellular  tissue  from  the  sterno-thyi'oid  muscles. 

The  costo-clavicular  ligament  {rhomboid)  is  a  thick  fasciculus  of 
fibres,  connecting  the  sternal  extremity  of  the  clavicle  with  the 
cartilage  of  the  first  rib.  It  is  situated  obliquely  between  the  rib 
and  the  under  surface  of  the  clavicle.  It  is  in  relation  in  front 
with  the  tendon  of  origin  of  the  subclavius  muscle,  and  behind 
with  the  subclavian  vein. 

Actions. — The  movements  of  the  sterno-clavicular  articulation, 
arc  a  gliding  movement  of  the  fibro-cartilage  with  the  clavicle,  upon 
the  articular  surface  of  the  sternum  in  the  directions  forwards, 
backwards,  upwards,  and  downwards;  and  circumduction.  This 
articulation  is  the  centre  of  the  movements  of  the  shoulder. 


SCAPULO-CLAVICULAR  LIGAMENTS, 


119 


ligament 


in   dislocation  of  the 


Fig.  52.* 


The  rupture  of  the  rhomboid 
sternal  end  of  the  clavicle,  gives 
rise  to  the  deformity  peculiar  to 
this  accident. 

The  interarticular  fibro-cartilage  is 
nearly  circular  in  form,  and  thicker 
at  the  edges  than  in  the  centre.  It 
is  attached  above,  to  the  clavicle ; 
below  to  the  cartilage  of  the  first 
rib ;  and  throughout  the  rest  of  its 
circumference  to  the  anterior  and 
posterior  sterno-clavicular  liga- 
ment ;  it  divides  the  joint  into  two 
cavities,  which  are  hned  by  distinct 
synovial  membranes.  This  cartilage  is  sometimes  pierced  through 
its  centre,  and  not  unfrequently  absorbed  to  a  greater  or  less  extent, 
particularly  at  its  lower  part. 

2.  Scapulo-claviculai'  Articulation. — The  ligaments  of  the  scapular 
end  of  the  clavicle  are,  the 

Superior  acromio-clavicular. 
Inferior  acromio-clavicular, 
Coraco-clavicular  (trapezoid  and  conoid), 

Interarticular  fibro-cartilage, 

Two  synovial  membranes. 

The  superior  acromio-clavicular  ligament  is  a  moderately  thick 
plane  of  superimposed  fibres  passing  between  the  extremity  of  the 
clavicle  and  the  acromion,  upon  the  upper  surface  of  the  joint. 

The  inferior  acromio-clavicular  ligament  is  a  thin  plane  situated 
upon  the  under  surface.  These  two  hgaments  are  continuous  with 
each  other  in  front  and  behind,  and  form  a  complete  capsule  around 
the  joint. 

The  coraco-clavicular  ligament  (trapezoid,  conoid)  is  a  thick  fasci- 
culus of  ligamentous  fibres,  passing  obhquely  between  the  base  of  the 
coracoid  process  and  the  under  surface  of  the  clavicle,  and  holding 
the  end  of  the  clavicle  in  firm  connexion  with  the  scapula.  When  seen 
from  before,  it  has  a  quadrilateral  form :  hence  it  is  name  trapezoid: 
and,  examined  from  behind,  it  has  a  triangular  form,  the  base  being 
upwards ;  hence  another  name,  conoid. 

The  interarticular  fibro-cartilage  is  often  indistinct,  from  having 
partial  connexions  with  the  fibro-cartilaginous  surfaces  of  the  two 
bones  between  which  it  is  placed,  and  not  unfrequently  absent. 
When  partial,  it  occupies  the  upper  part  of  the  articulation.     The 

*The  ligaments  of  the  sterno-clavicular  and  costo-sternal  articulations.  1.  The 
anterior  sterno-clavicular  ligament.  2.  The  inter-clavicular  ligament.  3.  The  costo- 
clavicular or  rhomboid  ligament,  seen  on  both  sides.  4.  The  inter-articular  fibro- 
cartilage,  brought  into  view  by  the  removal  of  the  anterior  and  posterior  ligaments. 
5.  The  anterior  costo-sternal  ligaments  of  the  first  and  second  ribs. 


120 


SHOULDER  JOINT. 


Fiff.  53* 


synovial  me?nbranes  are  very  delicate.  There  is  only  one,  when  the 
fibro-cartilage  is  incomplete. 

Actions. — The  acromio-clavicular  articulation  admits  of  two  move- 
ments, the  gliding  of  the  surfaces  upon  each  other ;  and  the  rotation 
of  the  scapula,  upon  the  extremity  of  the  clavicle. 

3.  The  Proper  ligaments  of  the  Scapula  are  the 

Coraco-acromial, 
Transverse. 

The  coraco-acromial  ligament  is  a  broad  and  thick  triangular 
band,  which  forms  a  protecting  arch  over  the  shoulder  joint.  It  is 
attached  by  its  apex  to  the  point  of  the  acromion  process,  and  by 
its  base  to  the  external  border  of  the  coracoid  process  its  whole 
length.  This  ligament  is  in  relation  above  with  the  under  surface 
of  the  deltoid  muscle ;  and  below  with  the  tendon  of  the  supra-spi- 
natus  muscle,  a  bursa  mucosa  being  usually  interposed. 

The  transverse  or  coracoid  ligament  is 
a  narrow  but  strong  fasciculus  which 
crosses  the  notch  in  the  upper  border  of 
the  scapula,  from  the  base  of  the  cora- 
coid process,  and  converts  it  into  a  fora- 
men. The  supra-scapular  nerve  passes 
through  this  foramen. 

4.  Shoulder  Joint. — The  scapulo-hume- 
ral  articulation  is  an  enarthrosis,  or  ball 
and  socket  joint — its  ligaments  are,  the 
Capsular, 
Coraco-humeral, 
Glenoid. 
The  capsular  ligament  completely  en- 
circles the  articulating  head  of  the  sca- 
pula and  the  head  of  the  humerus,  and  is 
attached  to  the  neck  of  each  bone.     It  is 
thick   above,  where  resistance  is  most 
required,  and  is  strengthened  by  the  tendons  of  the  supra-spinatus, 
infra-spinatus,  teres  minor,  and  subscapularis  muscles :  below  it  is 
thin  and  loose.     The  capsule  is  incomplete  at  the  point  of  contact 
with  the  tendons,  so  that  they  obtain  upon  their  inner  surface  a 
covering  of  synovial  membrane 

The  _ 

obliquely  outwards  from  the  border  of  the  coracoid  process  to  the 
greater  tuberosity  of  the  humerus,  and  serves  to  strengthen  the 
superior  and  anterior  part  of  the  capsular  ligament. 

The  glenoid  ligament  is   the   prismoid  band  of  fibro-cartilage, 

*  The  lifrnmonts  of  tlie  scapula  and  shoulder  joint.  1.  The  superior  acromio-clavicu- 
lar ligament.  2.  The  coraco-clavicular  ligament;  this  aspect  of  the  ligament  is  named 
trapezoid.  3.  The  coraco-acromial  ligament.  4.  The  transverse  ligament.  5.  The 
capsular  ligament.  6.  The  coraco-humeral  ligament.  7.  The  long  tendon  of  the 
biceps  issuing  from  the  capsular  ligament,  and  entering  the  bicipital  groove. 


coraco-humeral  ligament  is  a  broad  band  which  descends 


ELKOW  JOINT.  121 

which  is  attached  around  the  margin  of  the  glenoid  cavity  for  the 
purpose  of  protecting  its  edges,  and  deepening  its  cavity.  It  divides 
superiorly  into  two  slips  which  are  continuous  with  the  long  tendon 
of  the  biceps ;  hence  the  ligament  is  frequently  described  as  being 
formed  by  the  spHtting  of  that  tendon.  The  cavity  of  the  articu- 
lation is  traversed  by  the  long  tendon  of  the  biceps  which  is 
enclosed  in  a  sheath  of  synovial  membrane  in  its  passage  through 
the  joint. 

The  synovial  membrane  of  the  shoulder  joint  is  very  extensive ;  it 
communicates  anteriorly  through  an  opening  in  the  capsular  liga- 
ment with  a  large  bursal  sac,  which  lines  the  under  surface  of  the 
tendon  of  the  subscapularis  muscle.  Superiorly,  it  frequently  com- 
municates through  another  opening  in  the  capsular  ligament  with 
a  bursal  sac  belonging  to  the  infra-spinatus  muscle ;  and  it  more- 
over forms  a  sheath  around  that  portion  of  the  tendon  of  the  biceps, 
which  is  included  within  the  joint. 

The  muscles  immediately  surrounding  the  shoulder  joint  are  the 
subscapularis,  supra-spinatus,  infra-spinatus,  teres  minor,  long  head 
of  the  triceps,  and  deltoid ;  the  long  tendon  of  the  biceps  is  within 
the  capsular  ligament. 

Actions. — The  shoulder  joint  is  capable  of  every  variety  of  motion, 
viz.  of  movement  forwards  and  backwards,  of  abduction,  and  adduc- 
tion, of  circumduction  and  rotation. 

5.  Elbow  Joint. — The  elbow  is  a  ginglymoid  articulation;  its 
Ugaments  Sirefour  in  number  : — 

Anterior, 
Posterior, 
Internal  lateral. 
External  lateral. 

The  anterior  ligament  is  a  broad  and  thin  membranous  layer, 
descending  from  the  anterior  surface  of  the  humerus,  immediately 
above  the  joint,  to  the  coronoid  process  of  the  ulna  and  orbicular 
ligament.  On  each  side  it  is  connected  with  the  lateral  Ugaments. 
It  is  composed  of  fibres  which  pass  in  three  different  directions, 
vertical,  transverse,  and  oblique,  the  latter  being  extended  from 
within  outwards  to  the  orbicular  ligament,  into  which  they  are 
attached  inferiorly.  This  ligament  is  covered  in  by  the  brachialis 
anticus  muscle. 

The  posterior  ligament  is  a  broad  and  loose  fold  passing  between 
the  posterior  surface  of  the  humerus  and  the  anterior  surface  of  the 
base  of  the  olecranon,  and  connected  at  each  side  with  the  lateral 
ligaments.     It  is  covered  in  by  the  tendon  of  the  triceps. 

The  internal  lateral  ligament  is  a  thick  triangular  layer,  attached 
above,  by  its  apex,  to  the  internal  condyle  of  the  humerus ;  and 
below,  by  its  expanded  border,  to  the  margin  of  the  greater  sig- 
moid cavity  of  the  ulna,  extending  from  the  coronoid  process  to 
the  olecranon.     At  its  insertion  it  is  intermingled  with  some  trans- 

16 


122 


ELBOW  JOINT. 


verse  fibres.     The  internal  lateral  ligament  is  in  relation  posteriorly 
with  the  ulnar  nerve. 


The  external  lateral  ligament  is  a  strong  and  narrow  band,  which 
descends  from  the  external  condyle  of  the  humerus,  to  be  inserted 
into  the  orbicular  ligament,  and  into  the  ridge  on  the  ulna,  with 
which  the  posterior  part  of  the  lateral  ligament  is  connected.  This 
ligament  is  closely  united  with  the  tendon  of  origin  of  the  supinator 
brevis  muscle. 

The  synovial  membrane  is  extensive,  and  is  reflected  from  the 
cartilaginous  surfaces  of  the  bones  upon  the  inner  surface  of  the 
ligaments.  It  surrounds  inferiorly  the  head  of  the  radius,  and 
forms  an  articulating  sac  between  it  and  the  lesser  sigmoid  notch. 

The  muscles  immediately  surrounding,  and  in  contact  with,  the 
elbow  joint,  are  in  front,  the  brachiahs  anticus  ;  to  the  inner  side, 
the  pronator  radii  teres,  flexor  sublimis  digitorum,  and  flexor  carpi 
ulnaris;    externally,  the  extensor    carpi  radiaUs  brevier,  extensor 

*  An  internal  view  of  the  ligaments  of  the  elbow  joint.  1.  The  anterior  ligament. 
2.  The  internal  lateral  ligament.  3.  The  orbicular  ligament.  4.  The  oblique  liga- 
ment. 5.  The  interosseous  ligament.  G.  The  internal  condyle  of  the  humerus,  which 
conceals  the  posterior  ligament. 

t  An  external  view  of  the  elbow  joint.  1.  The  humerus.  2.  The  ulna.  3.  The 
radius.  4.  The  external  lateral  ligament  inserted  inferiorly  into  (5)  the  orbicular  liga- 
ment.  6.  The  posterior  extremity  of  the  orbicular  ligiiment  spreading  out  at  its  inser- 
tion into  the  ulna.  7.  The  anterior  ligament,  scarcely  ap|)arcnt  in  this  view  of  the 
articulation.  8.  The  posterior  ligament,  thrown  into  folds  by  the  extension  of  the  joint. 


ELBOW  JOINT.  123 

communis  digitorum,  extensor  carpi  ulnaris,  anconeus,  and  supi- 
nator brevis  ;  and  behind,  the  triceps. 

Actions. — The  movements  of  the  elbow  joint  are  jlexion  and 
extension,  which  are  performed  with  remarkable  precision.  The 
extent  to  which  these  movements  are  capable  of  being  effected,  is 
limited,  in  front  by  the  coronoid  process,  and  behmd  by  the  ole- 
cranon. 

6.  The  Radio-ulnar  Articulation. — The  radius  and  ulna  are  firmly 
held  together  by  ligaments  which  are  connected  with  both  extre- 
mities of  the  bones,  and  with  the  shaft ;  they  are,  the 

Orbicular,      •  Anterior  inferior, 

Oblique,  Posterior  inferior, 

Interosseous,  Interarticular  fibro-cartilage. 

The  orbicular  ligament  {annular,  coronary)  is  a  firm  band  several 
lines  in  breadth,  which  surrounds  the  head  of  the  radius,  and  is 
attached  by  each  end  to  the  extremities  of  the  lesser  sigmoid  cavity. 
It  is  strongest  behind  where  it  receives  the  external  lateral  ligament, 
and  is  lined  on  its  inner  surface  by  a  reflection  of  the  synovial 
membrane  of  the  elbow  joint. 

The  rupture  of  this  ligament  permits  of  the  dislocation  of  the 
head  of  the  radius. 

The  oblique  ligament  is  a  narrow  slip  of  ligamentous  fibres, 
descending  obliquely  from  the  base  of  the  coronoid  process  of  the 
ulna  to  the  lower  part  of  the  tuberosity  of  the  radius. 

The  interosseous  ligament  is  a  broad  and  thin  plane  of  aponeurotic 
fibres  passing  obliquely  downwards  from  the  sharp  ridge  on  the 
radius  to  that  on  the  ulna.  It  is  deficient  superiorly,  is  broader  in 
the  middle  than  at  each  extremity,  and  is  perforated  at  its  lower 
part  for  the  passage  of  the  anterior  interosseous  artery.  The  pos- 
terior interosseous  artery  passes  backwards  between  the  oblique 
ligament  and  the  upper  border  of  the  interosseous  ligament.  This 
ligament  affords  an  extensive  surface  for  the  attachment  of  muscles. 

The  interosseous  ligament  is  in  relation,  in  front,  with  the  flexor 
profundus  digitorum,  the  flexor  longus  pollicis,  and  pronator  quad- 
ratus  muscle,  and  with  the  anterior  interosseous  artery  and  nerve ; 
and  behind  with  the  supinator  brevis,  extensor  ossis  metacarpi 
pollicis,  extensor  primi  internodii  pollicis,  extensor  secundi  inter- 
nodii  pollicis,  and  extensor  indicis  muscle,  and  near  the  wrist  "udth 
the  anterior  interosseous  artery  and  posterior  interosseous  nerve. 

The  anterior  inferior  ligament  is  a  thin  fasciculus  of  fibres,  passing 
transversely  between  the  radius  and  ulna. 

The  posterior  inferior  ligament  is  also  thin  and  loose,  and  has  the 
same  disposition  on  the  posterior  surface  of  the  articulation. 

The  interarticular,  or  triangular  fibro-cartilage,  acts  the  part  of  a 
ligament  between  the  lower  extremities  of  the  radius  and  ulna.  It 
is  attached  by  its  apex  to  a  depression  on  the  inner  surface  of  the 
styloid  process  of  the  ulna,  and  by  its  base  to  the  edge  of  the  radius. 
This  fibro-cartilage  is  lined  upon  its  upper  surface  by  a  synovial 


124 


CARPAL  ARTICULATIONS. 


membrane,  which  forms  a  diiplicature  between  the  radius  and  ulna, 
and  is  called  the  memhrana  sacciformis.  By  its  lower  surface  it 
enters  into  the  articulation  of  the  wrist-joint. 

Actions. — The  movements  taking  place  between  the  radius  and 
the  ulna,  are  the  rotation  of  the  former  upon  the  latter ;  rotation 
forwards  being  termed  pronation,  and  rotation  backwards  supina- 
tion. In  these  movements  the  head  of  the  radius  turns  upon  its 
own  axis,  within  the  orbicular  ligament  and  the  lesser  sigmoid 
notch  of  the  ulna ;  while  inferiorly  the  radius  presents  a  con- 
cavity which  moves  upon  the  rounded  head  of  the  ulna.  The 
"^^  movements    of ,  the    radius    are    chiefly 

limited  by  the  anterior  and  posterior  in- 
ferior ligaments,  hence  these  are  not  un- 
frequently  ruptured  in  great  muscular 
efforts. 

7.  Wrist  Joint — The  wrist  is  a  gingly- 
moid  articulation ;  the  articular  surfaces 
entering  into  its  formation  being  the  ra- 
dius and  under  surface  of  the  triangular 
fibro-cartilage  above,  and  the  rounded 
surfaces  of  the  scaphoid,  semilunar,  and 
cuneiform  bone  below ;  its  ligaments  are 
four  in  number. 


Fiff.  56  * 


Anterior, 
Posterior, 
Internal  lateral. 
External  lateral. 

The  anterior  ligament  is  a  broad  and 
membranous  layer  consisting  of  three  fas- 
ciculi, which  pass  between  the  lower  part 
of  the  radius,  and  the  scaphoid,  semilu- 
nar, and  cuneiform  bones. 

The  posterior  ligament,  also  thin  and 
loose,  passes  between  the  posterior  surface  of  the  radius,  and  the 
posterior  surface  of  the  semilunar  and  cuneiform  bones. 

*  The  ligaments  of  the  anterior  aspect  of  the  wrist  and  hand.  1.  The  lower  part 
of  the  interosseous  membrane.  2.  The  anterior  inferior  radio-ulnar  ligament.  3.  The 
anterior  ligament  of  the  wrist  joint.  4.  Its  external  lateral  ligament.  5.  Its  internal 
lateral  ligament.  6.  The  palmar  ligaments  of  the  carpus.  7.  The  pisiform  bone, 
with  its  ligaments.  8.  The  ligaments  connecting  the  second  range  of  carpal  bones 
with  the  metacarpal,  and  the  metacarpal  witli  each  other.  !3.  Tlie  capsular  ligament 
of  the  carpo-metacarpal  articulation  of  the  thumb.  10.  Anterior  ligament  of  the  meta- 
carpo-phalangeal  articulation  of  the  thumb.  11.  One  of  the  lateral  ligaments  of  that 
articulation.  12.  Anterior  ligament  of  the  metacarpo-phalangcal  articulation  of  the 
index  finger;  these  hgaments  have  been  removed  in  the  other  fingers.  13.  Lateral 
ligaments  of  the  same  articulation ;  the  corresponding  ligaments  are  seen  in  the 
other  articulations.  14.  Transverse  ligament  connecting  the  heads  of  the  metacarpal 
bones  of  the  index  and  middle  fingers  ;  the  same  ligament  is  seen  between  the  other 
fingers.  15.  Anterior  and  one  lateral  ligament  of  the  phalangeal  articulation  of  the 
thumb.  16.  Anterior  and  lateral  ligaments  of  the  phalangeal  articulations  of  the 
index  finger  ;  the  anterior  ligaments  arc  removed  in  the  other  fingers. 


WRIST  JOINT.  125 

The  internal  lateral  ligament  extends  from  the  styloid  process  of 
the  ulna  to  the  cuneiform  and  pisiform  bone. 

The  external  lateral  ligament  is  attached  by  one  extremity  to  the 
styloid  process  of  the  radius,  and  by  the  other  to  the  side  of  the 
scaphoid  bone.  The  radial  artery  rests  on  this  ligament  as  it 
passes  backwards  to  the  first  metacarpal  space. 

The  synovial  membrane  of  the  wrist  joint  lines  the  under  surface 
of  the  radius  and  interarticular  fibro-cartilage  above,  and  the  first 
row  of  bones  of  the  carpus  below. 

The  relations  of  the  wrist  joint  are  the  flexor  and  extensor  ten- 
dons by  which  it  is  surrounded,  and  the  radial  and  ulnar  artery. 

Actions. — The  movements  of  the  wrist  joint  ^xe  flexion,  extension, 
adduction,  abduction,  and  circumduction.  In  these  motions  the  arti- 
cular surfaces  glide  upon  each  other. 

Articulations  between  the  Carpal  Bones. — These  are  amphi-arthro- 
dial  joints,  with  the  exception  of  the  conjoined  head  of  the  os  mag- 
num and  unciforme,  which  is  received  into  a  cup  formed  by  the 
scaphoid,  semilunar,  and  cuneiform  bones,  and  constitutes  an  enar- 
throsis.     The  ligaments  are, 

Dorsal, 
Palmar, 
Interosseous, 
Anterior  annular. 

The  dorsal  ligaments,  are  ligamentous  bands,  that  pass  from  bone 
to  bone  in  every  direction,  upon  the  dorsal  surface  of  the  carpus. 

The  palmar  ligaments  are  fasciculi  of  the  same  kind,  but 
stronger  than  the  dorsal,  having  the  like  disposition  upon  the  palmar 
surface. 

The  interosseous  ligaments  are  situated  between  the  adjoining 
bones  in  each  range :  in  the  upper  range  they  close  the  upper 
part  of  the  spaces  between  the  scaphoid,  semilunar,  and  cuneiform 
bones ;  in  the  lower  range  they  are  stronger  than  in  the  upper,  and 
connect  the  os  magnum  on  the  one  side  to  the  unciforme,  on  the 
other  to  the  trapezoides,  and  leave  intervals  through  which  the 
synovial  membrane  is  continued  to  the  bases  of  the  metacarpal 
bones. 

The  anterior  annular  ligament  is  a  firm  ligamentous  band,  which 
connects  the  bones  of  the  two  sides  of  the  carpus.  It  is  attached 
by  one  extremity  to  the  trapezium  and  scaphoid,  and  by  the  other 
to  the  unciform  process  of  the  unciforme  and  the  base  of  the  pisi- 
form bone,  and  forms  an  arch  over  the  anterior  surface  of  the 
carpus,  beneath  which  the  tendons  of  the  long  flexors  and  the 
median  nerve  pass  into  the  palm  of  the  hand. 

The  articulation  of  the  pisifm^m  bone  with  the  cuneiform,  is  pro- 
vided with  a  distinct  synovial  membrane,  which  is  protected  by 
fasciculi  of  ligamentous  fibres,  forming  a  kind  of  capsule  around  the 
joint ;  they  are  inserted  into  the  cuneiforme,  unciforme,  and  base  of 
the  metacarpal  bone  of  the  little  finger. 


126 


CARPO-METACARPAL  ARTICULATION. 


Fig.  57. 


Synovial  membranes. — There  are  five  synovial  membranes  enter- 
ing into  the  composition  of  the  articulations  of  the  carpus : — 

The  -first  is  situated  between  the  lower  end  of  the  ulna  and  the 
interarticular  fibro-cartilage  ;  it  is  called  sacciform,  from  forming 
a  sacculus  between  the  lateral  articulation  of  the  ulna  with  the 
radius. 

The  second  is  situated  between  the  lower  surface  of  the  radius 
and  interarticular  fibro-cartilage  above,  and  the  first  range  of  bones 
of  the  carpus  below. 

The  third  is  the  most  extensive  of  the  synovial  membranes  of  the 
wrist ;  it  is  situated  between  the  two  rows  of  carpal  bones,  and 
passes  between  the  bones  of  the  second  range,  to  invest  the  carpal 
extremities  of  the  four  metacarpal  bones  of  the  fingers. 

The  fourth  is  the  synovial  membrane  of  the  articulation  of  the 
metacarpal  bone  of  the  thumb  with  the  trapezium. 

The  fifth  is  situated  between  the  pisiform  and  cuneiform  bone. 
Actions. — Very  little  movement  exists  between  the  bones  in  each 
range,  but  more  is  permitted  between  the  two  ranges.   The  motions 
in  the  latter  situation  are  those  of  flexion  and  extension. 

9.  The    Carpo-metacarpal   Articulation. — The    second  row   of 

bones  of  the  carpus  articulates  with 
the  metacarpal  bones  of  the  four  fin- 
gers by  dorsal  and  palmar  ligaments  ; 
and  the  metacarpal  bone  of  the  thumb 
with  the  trapezium  by  a  true  capsular 
ligament. 

The  dai^sal  ligaments  are  strong  fas- 
cicuh  which  pass  from  the  second 
range  of  carpal  to  the  metacarpal 
bones. 

The  palmar  ligaments  are  thin  fasci- 
culi arranged  upon  the  same  plan  on 
the  palmar  surface. 

The   synovial  membrane  is  a  con- 
tinuation of  the  great  synovial  mem- 
brane of  the  two  rows  of  carpal  bones. 
The  capsular  ligament  of  the  thumb 
is  one  of  the  three  true  capsular  liga- 
ments of  the  skeleton ;  the  other  two  being  the  shoulder-joint  and 
hip-joint.     The  articulation  has  a  proper  synovial  membrane. 

*  A  diagram  showing  the  disposition  of  the  five  synovial  membranes  of  the  wrist 
joint.  1.  Tiie  sacciform  membrane.  2.  The  second  synovial  membrane.  3,  3,  The 
third,  or  large  synovial  membrane.  4.  The  synovial  mcml)rane  between  the  pisiform 
bono  and  the  cunoiformc.  5.  The  synovial  membrane  of  tlie  metacarpal  articulation 
of  the  thumb.  6.  Tlie  lower  extremity  of  the  radius.  7.  The  lower  extremity  of  the 
ulna.  8.  The  interarticular  fibro-cartilage.  S.  The  scaphoid  bone.  L.  The  semi- 
lunarc.  C  The  cimeiibrme;  the  interosseous  ligaments  arc  seen  passing  between 
these  three  bones  and  separating  the  articulation  of  the  wrist  (2)  from  the  articulation 
of  the  carpal  bones  (3).  V.  The  pisiformc.  T.  Tlic  tra|)czium.  T=.  The  trapc- 
zoides.  M.  The  os  magnum.  U.  The  unciforme  ;  interosseous  ligaments  are  seen 
connecting  the  os  magnum  with  the  trapezoides  and  unciforme.  9.  The  base  of  the 
metacarpal  bone  of  the  thumb.     10,  10.  The  bases  of  the  other  metacarpal  bones. 


METACARPO-PHALANGEAL  ARTICULATION.  127 

The  metacarpal  hones  of  the  four  fingers  are  firmly  connected  at 
their  bases  by  means  of  dorsal  and  palmar  ligaments,  which  extend 
transversely  from  one  bone  to  the  other,  and  by  interosseous  Uga- 
ments  which  pass  between  their  contiguous  surfaces.  Their  lateral 
articular  facets  are  lined  by  a  reflection  of  the  great  synovial  mem- 
brane of  the  two  rows  of  carpal  bones. 

Actions. — The  movements  of  the  metacarpal  on  the  carpal  bones 
are  restricted  to  a  slight  degree  of  sliding  motion,  with  the  excep- 
tion of  the  articulation  of  the  metacarpal  bone  of  the  thumb  with 
the  trapezium.  In  the  latter  articulation,  the  movements  are, 
Jiexion,  extension,  adduction,  abduction,  and  circumduction. 

10.  Metacarpo-phalangeal  Articulation. — The  metacarpo-phalan- 
geal  articulation  is  a  ginglymoid  joint:  its  ligaments  are  four  in 
number. 

Anterior, 
Two  lateral, 
Transverse. 

The  anterior  ligaments  are  thick  and  fibro-cartilaginous,  and  form 
part  of  the  articulating  surface  of  the  joints.  They  are  grooved 
externally  for  the  lodgment  of  the  flexor  tendons,  and  by  their 
internal  aspect  form  part  of  the  articular  surface  for  the  head  of  the 
metacarpal  bone. 

The  lateral  ligaments  are  strong  narrow  fasciculi,  holding  the 
bones  together  at  each  side. 

The  transverse  ligaments  are  strong  ligamentous  bands  passing 
between  the  anterior  Ugaments,  and  connecting  together  the  heads 
of  the  metacarpal  bones  of  the  four  fingers. 

The  expansion  of  the  extensor  tendon  over  the  back  of  the  fingers 
takes  the  place  of  a  posterior  ligament. 

Actions. — This  articulation  admits  of  movement  in  four  different 
directions,  viz.  oi  Jiexion,  extension,  adduction,  and  abduction,  the 
two  latter  being  hmited  to  a  small  extent.  It  is  also  capable  of  cir- 
cumduction. 

11.  Articulation  of  the  Phalanges. — These  articulations  are  gingly- 
moid joints :  they  are  formed  by  three  Ugaments. 

Anterior, 
Two  lateral. 

The  anterior  ligament  is  firm  and  fibro-cartilaginous,  and  forms 
part  of  the  articular  surface  for  the  head  of  the  phalanges.  Exter- 
nally it  is  grooved  for  the  reception  of  the  flexor  tendons. 

The  lateral  ligaments  are  very  strong;  they  are  the  principal 
bond  of  connexion  between  the  bones. 

The  extensor  tendon  takes  the  place  and  performs  the  office  of  a 
posterior  ligament. 

Actions. — The  movements  of  the  phalangeal  joints  are  Jiexion  and 
extension,  these  movements  being  more  extensive  between  the  first 
and  second  phalanges  than  between  the  second  and  third. 


128  HIP  JOINT. 


LIGAMENTS  OF  THE  LOWER  EXTREMITV. 

The  ligaments  of  the  lower  extremity,  like  those  of  the  upper,  may 
be  arranged  m  the  order  of  the  joints  to  which  they  belong  ;  these 
are,  the 

1.  Hip  joint. 

2.  Knee  joint. 

3.  Articulation  between  the  tibia  and  fibula. 

4.  Ankle  joint. 

5.  Articulation  of  the  tarsal  bones. 

6.  Tarso-metatarsal  articulation. 

7.  Metatarso-phalangeal  articulation. 

8.  Articulation  of  the  phalanges. 

1.  Hij)  Joint. — The  articulation  of  the  head  of  the  femur  with  the 
acetabulum  constitutes  an  enarthrosis,  or  ball  and  socket  joint. 
The  articular  surfaces  are  the  cup-shaped  cavity  of  the  acetabulum 
and  the  rounded  head  of  the  femur;  the  ligaments  are  jive  in 
number,  viz. : 

Capsular, 

Ilio-femoral, 

Teres, 

Cotyloid, 

Transverse. 

The  capsular  ligament  (fig.  50,  8)  is  a  strong  ligamentous  cap- 
sule, embracing  the  acetabulum  superiorly,  and  inferiorly  the  neck 
of  the  femur,  and  connecting  the  two  bones  firmly  together.  It  is 
much  thicker  upon  the  upper  part  of  the  joint,  where  more  resist- 
ance is  required,  than  upon  the  under  part,  and  extends  farther  upon 
the  neck  of  the  femur  on  the  anterior  and  superior  than  on  the  pos- 
terior and  inferior  side,  being  attached  to  the  intertrochanteric  line 
in  front,  to  the  base  of  the  great  trochanter  above,  and  to  the  middle 
of  the  neck  of  the  femur  behind. 

The  ilio-femoral  ligament*  (fig.  50, 9)  is  an  accessory  and  radiating 
band,  which  descends  obliquely  from  the  anterior  inferior  spinous 
process  of  the  ilium  to  the  anterior  intertrochanteric  line,  and 
strengthens  the  anterior  portion  of  the  capsular  ligament. 

The  ligamentum  teres  (fig.  51,  7),  triangular  in  shape,  is  attached 
by  a  rounded  apex  to  the  depression  just  below  the  middle  of  the 
head  of  the  femur,  and  by  its  base,  which  divides  into  two  fasciculi, 
into  the  borders  of  the  notch  of  the  acetabulum.  It  is. formed  by  a 
fasciculus  of  fibres  of  variable  size,  surrounded  by  synovial  mem- 
brane ;  sometimes  the  synovial  membrane  alone  exists,  or  the  liga- 
ment is  wholly  absent. 

The  cotyloid  ligament  (fig.  51,  6)  is  a  prismoid  cord  of  fibro-car- 

*  Called  also  ligamenlum  adsciiiliuin. 


KA'EE  JOINT.  129 

tilage,  attached  around  the  margin  of  the  acetabulum,  and  serving 
to  deepen  the  cavity  and  protect  its  edges.  It  is  much  thicker  upon 
the  upper  and  outer  border  of  the  acetabukim  than  in  front,  and 
consists  of  fibres  which  arise  from  the  whole  circumference  of  the 
brim,  and  interlace  with  each  other  at  acute  angles. 

The  transverse  ligament  is  a  strong  fasciculus  of  ligamentous 
fibres,  continuous  with  the  cotyloid  ligament,  and  extended  across 
the  notch  in  the  acetabulum.  It  converts  the  notch  into  a  foramen, 
through  which  the  articular  branches  of  the  internal  circumflex  and 
obturator  arteries  enter  the  joint. 

The  fossa  at  the  bottom  of  the  acetabulum  is  filled  by  a  mass  of 
fat,  covered  with  synovial  membrane,  which  serves  as  an  elastic 
cushion  to  the  head  of  the  bone  during  its  movements.  This  was 
considered  by  Havers  as  the  synovial  gland. 

The  synovial  membrane  is  extensive ;  it  invests  the  head  of  the 
femur,  and  is  continued  around  the  ligamentum  teres  into  the  ace- 
tabulum ;  it  is  thence  reflected  upon  the  inner  surface  of  the  cap- 
sular hgament. 

The  muscles  immediately  surrounding  and  in  contact  with  the 
hip  joint  are,  in  front,  the  psoas  and  iliacus,  which  are  separated 
from  the  capsular  ligament  by  a  large  synovial  bursa ;  above, 
the  short  head  of  the  rectus,  and  the  gluteus  minimus  ;  behind,  the 
pyriformis,  gemellus  superior,  obturator  internus,  gemellus  inferior, 
and  quadratus  femoris ;  and  to  the  inner  side,  the  obturator  externus 
and  pectineus. 

Actions. — The  movements  of  the  hip  joint  are  very  extensive ; 
they  a.re  Jlexion,  extension,  adduction,  abduction,  circumduction,  and 
rotation. 

2.  Knee  Joint. — The  knee  is  a  ginglymoid  articulation  of  a  large 
size,  and  is  provided  with  numerous  ligaments  ;  they  are  thirteen  in 
number. 

Anterior  or  ligamentum  patellae, 

Posterior  or  ligamentum  posticum  Winslowi, 

Internal  lateral. 

Two  external  lateral, 

Anterior  or  external  crucial, 

Posterior  or  internal  crucial, 

Transverse, 

Two  coronary, 

Ligamentum  mucosum,  )    ^  , 
Ligamenta  alaria,  \  /^'^^* 

Two  semilunar  fibro-cartilages, 
Synovial  membrane. 

The  five  first  are  external  to  the  articulation;  the  ^we  next  are 
internal  to  the  articulation ;  the  three  remaining  are  mere  folds  of 
synovial  membrane,  and  have  no  title  to  the  name  of  ligaments.  In 
addition  to  the  ligaments,  there  are  two  fibro-cartilages,  wliich  are 
sometimes  very  erroneously  considered  among  the  ligaments ;  and 

17 


130  .  KNEE  JOINT, 

a  synovial  membrane,  which  is  still  more  improperly  named  the 
capsular  ligament. 

The  anterior  ligament  or  ligamentum  fatellce,  is  the  prolongation 
of  the  tendon  of  the  extensor  muscles  of  the  thigh  downwards  to  the 
tubercle  of  the  tibia.  It  is,  therefore,  no  ligament ;  and,  as  we  have 
before  stated,  that  the  patella  is  simply  a  sesamoid  bone,  developed 
in  the  tendon  of  the  extensor  muscles  for  the  defence  of  the  front  of 
the  knee  joint,  it  has  no  title  to  consideration,  either  as  a  ligament 
of  the  knee  joint  or  as  a  ligament  of  the  patella. 

A  small  bursa  mucosa  is  situated  between  the 
Fig.  58.*  ligamentum  patellae,  near  to  its  insertion,  and  the 

front  of  the  tibia,  and  another  of  larger  size  is 
placed  between  the  patella  and  the  fascia  lata, 
which  extends  over  its  anterior  surface. 

The  posterior  ligament — ligamentum  posticum 
Winslowi,^ — is  a  broad  expansion  of  ligamentous 
fibres  which  covers  the  whole  of  the  posterior 
part  of  the  joint.  It  is  divisible  into  two  lateral 
portions  which  invest  the  condyles  of  the  femur, 
and  a  central  portion  which  is  depressed  and 
formed  by  the  interlacement  of  fasciculi  passing 
in  different  directions.  The  strongest  of  these  fasci- 
culi is  that  which  is  derived  from  the  tendon  of  the 
semimembranosus  and  passes  obliquely  upwards 
and  outwards,  from  the  posterior  part  of  the  inner 
tuberosity  of  the  tibia  to  the  external  condyle.  Other  accessory 
fasciculi  are  given  off  by  the  tendon  of  the  popUteus  and  by  the 
heads  of  the  gastrocnemius.  The  middle  portion  of  the  ligament 
supports  the  popliteal  artery  and  vein,  and  is  perforated  by  several 
openings  for  the  passage  of  branches  of  the  azygos  articular  artery, 
and  for  the  nerves  of  the  joint. 

The  internal  lateral  ligament  is  a  broad  and  trapezoid  layer  of 
ligamentous  fibres,  attached  above  to  the  tubercle  on  the  internal 
condyle  of  the  femur,  and  below  to  the  side  of  the  inner  tuberosity 
of  the  tibia.  It  is  crossed  at  its  lower  part  by  the  tendons  of  the 
inner  hamstring  from  which  it  is  separated  by  a  synovial  bursa,  and 
it  covers  in  the  anterior  slip  of  the  semi-membranosus  tendon  and 
the  inferior  internal  articular  artery. 

External  lateral  ligaments. — The  long  external  lateral  ligament  is 
a  strong  rounded  cord,  which  descends  from  the  posterior  part  of 
the  tubercle  upon  the  external  condyle  of  the  femur  to  the  outer 

*  The  anterior  view  of  the  lignments  of  the  knee-joint.  1.  The  tendon  of  the 
quadriceps  extensor  muscle  of  the  leg.  2.  Tlie  patella.  3.  The  anterior  ligament,  or 
ligamentum  patellse,  near  its  insertion.  4,  4.  The  synovial  memhrane.  5.  Tlie  internal 
lateral  ligament.  6.  The  long  external  lateral  ligament,  7.  The  anterior  superior 
tibio-fihular  ligament. 

t  In  a  recent  dissection  in  Sydenham  College,  Mr.  Joseph  Chapman  observed  a  small 
fleshy  muscle,  connected  by  one  extremity  with  the  external  condyle  of  tlie  femur,  and 
inserted  by  the  otlier  into  that  portion  of  this  ligament  which  is  derived  from  the  tendon 
of  the  semimembranosus. 


KNEE  JOIXT. 


131 


Fig.  59. 


part  of  the  head  of  the  fibula.     The  shm^t  external  lateral  ligament 

is  an  irregular  fasciculus  situated  behind  the  pre- 
ceding, arising  from  the  external  condyle  near 

the   origin  of  the   head   of  the  gastrocnemius 

muscle,  and  inserted  into  the  posterior  part  of 

the  head  of  the  fibula.     It  is  firmly  connected 

with  the  external  semilunar  fibro-cartilage,  and 

appears   principally   intended   to    connect   that 

cartilage  with   the    fibula.     The   lono;  external 

lateral  ligament  is  covered  in  by  the  tendon  of 

the  biceps,  and  has  passing  beneath  it  the  tendon 

of  the  origin  of  the  popliteas  muscle,  and  the  in- 
ferior external  articular  artery. 

The  true  ligaments  ivit/iin  the  joint  are  the 

crucial,  transverse  and  coronary. 

The   anterior   or    external   crucial  ligament, 
arises  from  the  depression  upon  the  head  of  the 

tibia  in  front  of  the  spinous  process,  and  passes  upwards  and  back- 
wards to  be  inserted  into  the  inner  surface  of  the  outer  condyle  of 
the  femur,  as  far  as  its  posterior  border.  It  is  smaller  than  the 
posterior. 

The  posterior,  or  internal  crucial  ligament,  arises  from  the  depres- 
sion upon  the  head  of  the  tibia,  behind  the  spinous  process,  and 
passes  upwards  and  forwards  to  be  inserted  into  the  inner  condyle 
of  the  femur.  This  ligament  is  less  obhque  and  larger  than  the 
anterior. 

The  transverse  ligament  is  a  small  slip  of  fibres  which  extends 
transversely  from  the  external  semilunar  fibro-cartilage,  near  its 
anterior  extremity,  to  the  anterior  convexity  of  the  internal  car- 
tilage. 

The  coronary  ligaments  are  the  short  fibres  by  which  the  convex 
borders  of  the  semilunar  cartilages  are  connected  to  the  head  of  the 
tibia,  and  to  the  ligaments  surrounding  the  joint. 

The  semilunar  fibro-cartilagss,  are  two  falciform  plates  of  fibro- 
cartilage,  situated  around  the  margin  of  the  head  of  the  tibia,  and 
serving  to  deepen  the  surface  of  articulation  for  the  condyles  of  the 
femur.  They  are  thick  along  their  convex  border,  and  thin  and 
sharp  along  the  concave  edge. 

The  internal  semilunar  fibro-cartilage  forms  an  oval  cup  for  the 
reception  of  the  internal  condyle  ;  it  is  connected  by  its  convex 
border  to  the  head  of  the  tibia,  and  to  the  internal  and  posterior 


*  A  posterior  view  of  the  ligaments  of  the  knee-joint.  1.  Tlie  fasciculus  of  the  liga- 
mentum  posticum  Winslowi,  which  is  derived  from,  2.  Tiie  tendon  of  the  semi-mera- 
branosus  muscle  ;  the  latter  is  cut  short.  3.  The  process  of  the  tendon  which  spreads 
out  in  the  fascia  of  the  popliteus  muscle.  4.  The  process  which  is  sent  inwards  beneath 
the  internal  lateral  ligament.  5.  The  posterior  part  of  the  internal  lateral  ligament.  6. 
The  long  external  lateral  ligament.  7.  The  short  external  lateral  ligament.  8.  The 
tendon  of  the  popliteus  muscle  cut  short.  9.  The  posterior  superior  tibio-fibular 
ligament. 


132 


KNEE  JOINT. 


ligaments,  by  means  of  its  coronary^ligament ;  and  by  its  two 
extremities  is  firmly  implanted  into  the  depression  in  front  and 
behind  the  spinous  process.     The  external  semilunar  fihro-cartilage 


Fiff.  60* 


Fig.  61.t 


bounds  a  circular  fossa  for  the  external  condyle ;  it  is  connected  by 
its  convex  border  with  the  head  of  the  tibia,  and  to  the  external  and 
posterior  hgaments,  by  means  of  its  coronary  hgament ;  by  its  two 
extremities  it  is  inserted  into  the  depression  between  the  two  pro- 
jections which  constitute  the  spinous  process  of  the  tibia.     The  two 


*  The  right  knee  joint  laid  open  from  the  front,  in  order  to  show  the  internal  liga- 
ments. 1.  The  cartilaginous  surface  of  the  lower  extremity  of  the  femur  with  its 
two  condyles ;  the  figure  5  rests  upon  the  external ;  the  figure  3  upon  the  internal 
condyle.  2.  The  anterior  crucial  ligament.  3.  The  posterior  crucial  ligament.  4, 
The  transverse  ligament.  5.  The  attachment  of  the  ligamentum  mucosum,  the  rest 
has  been  removed.  6.  T)ie  internal  semilunar  fibro-cartilage.  7.  The  external  fibro- 
cartilage.  8.  A  part  of  the  ligamentum  patellae  turned  down.  9.  The  bursa,  situated 
between  the  ligamentum  patelte  and  the  head  of  the  tibia  ;  it  has  been  laid  open.  10. 
The  anterior  superior  tibio-fibular  ligament.  11.  The  upper  part  of  the  interosseous 
membrane,  the  opening  above  this  membrane  is  for  the  passage  of  the  anterior  tibial 
artery. 

t  A  longitudinal  section  of  the  left  knee  joint,  showing  the  reflections  of  its  synovial 
membrane.  1.  The  cancellous  structure  of  the  lower  part  of  the  femur.  2.  The 
tendon  of  the  extensor  muscles  of  the  leg.  3.  Tlie  patella.  4.  The  ligamentum 
patellse.  5.  The  cancellous  structure  of  tlie  head  of  the  tibia.  6.  A  bursa  situated 
between  the  ligamentum  patcllce  and  the  head  of  the  tibia.  7.  The  mass  of  fat  pro- 
jecting into  the  cavity  of  the  joint  below  the  patella.  *  *  The  synovial  membrane. 
y.  The  pouch  of  synovial  membrane  which  ascends  between  tlic  tendon  of  the  extensor 
muscles  of  the  leg,  and  the  front  of  the  lower  extremity  of  the  femur.  9.  One  of  the  alar 
ligaments  ;  the  other  has  been  removed  with  tlie  opposite  section.  10.  I'jie  ligamentum 
mucosum  left  entire  ;  the  section  being  made  to  its  inner  side.  11.  TJie  anterior  or 
external  crucial  ligament.  12.  The  posterior  ligament.  The  scheme  of  the  synovial 
membrane  which  is  here  presented  to  the  student,  is  divested  of  all  unnecessary  com- 
plications.  It  may  be  traced  from  the  sacculus  (at  8),  along  the  inner  surface  of  the 
patella  ;  then  over  the  adipose  mass  (7)  from  whidi  it  throws  off  tlie  mucous  ligament 
(10) ;  then  over  the  head  of  the  tibia,  forming  a  sheath  to  the  crucial  ligaments  ;  then 
upwards  along  the  posterior  ligament  and  condyles  of  the  femur,  to  the  sacculus  whence 
its  examination  commenced. 


KNEE  JOINT,  133 

extremities  of  the  external  cartilage  being  inserted  into  the  same 
fossa,  form  almost  a  complete  circle,  and  the  cartilage  being  some- 
what broader  than  the  internal,  nearly  covers  the  articular  surface  of 
the  tibia.  The  external  semilunar  fibro-cartilage  besides  giving  off  a 
fasciculus  from  its  anterior  border  to  constitute  the  transverse  liga- 
ment, is  continuous  by  some  of  its  fibres  with  the  extremity  of  the 
anterior  crucial  ligament ;  posteriorly  it  divides  into  three  slips,  one, 
a  strong  cord,  ascends  obhquely  forwards  and  is  inserted  into  the 
anterior  part  of  the  inner  condyle  in  front  of  the  posterior  crucial 
ligament ;  another  is  the  fasciculus  of  insertion  into  the  fossa  of  the 
spinous  process ;  and  the  third,  of  small  size,  is  continuous  with  the 
posterior  part  of  the  anterior  crucial  ligament. 

The  ligamenium  mucosum  is  a  slender  conical  process  of  syno- 
vial membrane  enclosing  a  few  ligamentous  fibres  which  proceed 
from  the  transverse  ligament.  It  is  connected  by  its  apex,  with  the 
anterior  part  of  the  condyloid  notch,  and  by  its  base  is  lost  in  the 
mass  of  fat  which  projects  into  the  joint  beneath  the  patella. 

The  alar  ligaments  are  two  fringed  folds  of  synovial  membrane, 
extending  from  the  ligamentum  mucosum,  along  the  edges  of  the 
mass  of  fat  to  the  sides  of  the  patella. 

The  synovial  membrane  of  the  knee  joint  is  by  far  the  most  exten- 
sive in  the  skeleton.  It  invests  the  cartilaginous  surface  of  the 
condyles  of  the  femur,  of  the  head  of  the  tibia,  and  of  the  inner 
surface  of  the  patella ;  it  covers  both  surfaces  of  the  semilunar 
fibro-cartilages,  and  is  reflected  upon  the  crucial  ligaments,  and 
upon  the  inner  surface  of  the  ligaments  which  form  the  circum- 
ference of  the  joint.  On  each  side  of  the  patella,  it  lines  the  tendi- 
nous aponeuroses  of  the  vastus  internus  and  vastus  externus  muscles, 
and  forms  a  pouch  of  considerable  size  between  the  extensor  tendon 
and  the  front  of  the  femur.  It  also  forms  the  folds  in  the  interior  of 
the  joint,  called  "  ligamentum  mucosum,"  and  "  hgamenta  alaria." 
The  superior  pouch  of  the  synovial  membrane  is  supported  and 
raised  during  the  movements  of  the  limb  by  a  small  muscle,  the 
subcrureus  which  is  inserted  into  it. 

Beneath  the  ligamentum  patelljs  and  the  synovial  membrane  is 
a  considerable  mass  of  fat,  which  presses  the  membrane  towards 
the  interior  of  the  joint,  and  occupies  the  fossa  between  the  two 
condyles. 

Besides  the  proper  Ugaments  of  the  articulation,  the  joint  is  pro- 
tected on  its  anterior  part  by  the  fascia  lata,  which  is  thicker  upon 
the  outer  than  upon  the  inner  side,  by  a  tendinous  expansion  from 
the  vastus  internus,  and  by  some  scattered  ligamentous  fibres  w^hich 
are  inserted  into  the  sides  of  the  patella. 

Actions. — The  Imee  joint  is  one  of  the  strongest  of  the  articulia- 
tions  of  the  body,  while  at  the  same  time  it  admits  of  the  most  per- 
fect degree  of  movement  in  the  directions  o^  flexion  and  extension. 
During  flexion  the  articular  surface  of  the  tibia  glides  forward  on 
the  condyles  of  the  femur,  the  lateral  ligaments,  the  posterior,  and 
crucial  ligaments  are  relaxed,  while  the  ligamentum  patellce  being 


134  TIBIO-FIBULAR  ARTICULATION. 

put  upon  the  stretch,  serves  to  press  the  adipose  mass  into  the  vacuity 
formed  in  the  front  of  the  joint.  In  extension  all  the  ligaments  are 
put  upon  the  stretch  with  the  exception  of  the  ligamentum  patellas. 
When  the  knee  is  semi-flexed,  a  partial  degree  of  rotation  is 
permitted. 

3.  Articulation  between  the  Tibia  and  Fibula. — The  tibia  and 
fibula  are  held  firmly  connected  by  means  of  seven  hgaments,  viz. 

Anterior,  )    i 

-n    t    ■       ?  above. 

rostenor,  ) 

Interosseous  membrane, 
Interosseous  inferior, 

Anterior,  )  i    i 
-r,    ,    •   M  below, 
rostenor,  ) 

Transverse. 

The  anterior  superior  ligament  is  a  strong  fasciculus  of  parallel 
fibres  passing  obliquely  downwards  and  outwards  from  the  inner 
tuberosity  of  the  tibia,  to  the  anterior  surface  of  the  head  of  the 
fibula. 

The  'posterior  superior  ligament  is  disposed  in  a  similar  manner 
upon  the  posterior  surface  of  the  articulation. 

There  is  a  distinct  synovial  membrane  in  this  articulation. 

The  interosseous  membrane  or  superior  interosseous  ligament  is  a 
broad  layer  of  aponeurotic  fibres  passing  obliquely  downwards  and 
outwards,  from  the  sharp  ridge  on  the  tibia,  to  the  inner  edge  of  the 
fibula  and  crossed  at  an  acute  angle  by  a  few  fibres  passing  in  the 
opposite  direction.  The  ligament  is  deficient  above,  leaving  a  con- 
siderable interval  between  the  bones,  through  which  the  anterior 
tibial  artery  takes  its  course  forwards  to  the  anterior  aspect  of  the 
leg,  and  near  its  lower  third  there  is  an  opening  for  the  anterior 
peroneal  artery  and  vein. 

The  interosseous  membrane  is  in  relation^  in  front,  with  the 
tibiahs  anticus,  extensor  longus  digitorum,  and  extensor  proprius 
pollicis  muscle,  with  the  anterior  tibial  vessels  and  nerve,  and  with 
the  anterior  peroneal  artery ;  and  behind  with  the  tibialis  posticus, 
and  flexor  longus  digitorum  muscle,  and  with  the  posterior  peroneal 
artery. 

The  inferior  interosseous  ligament  consists  of  short  and  strong 
fibres,  which  hold  the  bones  firmly  together,  inferior ly,  where  they 
are  nearly  in  contact.  This  articulation  is  so  firm  that  the  fibula 
is  likely  to  be  broken  in  the  attempt  to  rupture  the  ligament. 

The  anterior  inferior  ligament  is  a  broad  band,  consisting  of  two 
fasciculi  of  parallel  fibres  that  pass  obliquely  across  the  anterior  as- 
pect of  the  articulation  of  the  two  bones  at  their  inferior  extremity, 
from  the  tibia  to  the  fibula. 

The  posterior  inferior  ligament  (fig.  G4.  2)  is  a  similar  band  upon 
the  posterior  surface  of  the  articulation.     Both  ligaments  project 


ANKLE  JOINT. 


135 


somewhat  below  the  margin  of  the  bones,  and  serve  to  deepen  the 
cavity  of  articulation  for  the  astragalus. 

The  transverse  ligament  (fig.  64.  3)  is  a  narrow  band  of  ligamen- 
tous fibres,  continuous  with  the  preceding,  and  passing  transversely 
across  the  back  of  the  ankle  joint  between  the  two  malleoli. 

The  synovial  membrane  of  the  inferior  tibio-fibular  articulation,  is 
a  duplicature  reflected  upwards  for  a  short  distance  between  the 
two  bones. 

Actions. — An  obscure  movement  exists  betM^een  the  tibia  and 
fibula,  which  is  principally  calculated  to  enable  the  latter  to  resist 
injury  by  yielding  for  a  trifling  extent  to  the  pressure  exerted. 

4.  Ankle  joint. — The  ankle  is  a  ginglymoid  articulation,  the  sur- 
faces entering  into  the  formation  of  the  joint  are  the  under  surface 
of  the  tibia  with  its  malleolus  and  the  malleolus  of  the  fibula,  above ; 
and  the  surface  of  the  astragalus  with  its  two  lateral  facets,  below. 
The  ligaments  are  three  in  number : — 
Anterior, 
Internal  lateral, 
External  lateral. 

The  anterior  ligament  is  a  thin  membranous  layer,  passing  from 
the  margin  of  the  tibia  to  the  astragalus  in  front  of  the  articular  sur- 
face.    It  is  in  relation,  in  front,  with  the  extensor  tendons  of  the 


Fig.  62.* 


Fig.  63.t 


great  and  lesser  toes,  with  the  tendon  of  the  tibialis  anticus  and  pero- 
neus  tertius,  and  with  the  anterior  tibial  vessels  and  nerve.  Pos- 
teriorly it  hes  in  contact  with  the  extra- synovial  adipose  tissue  and 
with  the  synovial  membrane. 

The  internal  lateral  ligament  or  deltoid,  is  a  triangular  layer  of 

*  An  internal  view  of  the  ankle  joint.  1.  The  internal  malleolus  of  the  tibia,  2,  2. 
Part  of  the  astragalus;  the  rest  is  concealed  by  the  ligaments.  3.  The  os  calcis.  4. 
The  scaphoid  bone.  5.  The  internal  cuneiform  bone.  6.  The  internal  lateral  or  del- 
toid ligament.  7,  The  anterior  ligament.  8.  The  tendo  Achillis ;  a  small  bursa  is 
seen  interposed  between  this  tendon  and  the  tuberosity  of  the  os  calcis. 

t  An  external  view  of  the  ankle  joint.  1.  Tlie  tibia.  2.  The  external  malleolus  of 
the  fibula.  3,  3.  The  astragalus.  4.  The  os  calcis.  5.  The  cuboid  bone.  6.  The  an- 
terior fasciculus  of  the  external  lateral  ligament  attached  to  the  astragalus.  7.  Its 
middle  fasciculus,  attached  to  the  os  calcis.  8.  Its  posterior  fasciculus,  attached  to  the 
astragalus.     9.  The  anterior  ligament  of  the  ankle. 


136  TARSAX   AKTICULATION. 

fibres  attached  superiorly  by  its  apex  to  the  internal  malleolus,  and 
inferiorly  by  an  expanded  base  to  the  astragalus,  os  calcis,  and  sca- 
phoid bone.  Beneath  the  superficial  layer  of  this  ligament  is  a  much 
stronger  and  thicker  fasciculus  of  fibres,  which  connects  the  apex  of 
the  internal  malleolus  with  the  side  of  the  astragalus. 

This  internal  lateral  ligament  is  covered  in  and  partly  concealed 
by  the  tendon  of  the  tibialis  posticus,  and  at  its  posterior  part  is  in 
relation  with  the  tendon  of  the  flexor  longus  digitorum,  and  of  the 
flexor  longus  pollicis. 

The  external  lateral  ligament  consists  of  three  strong  fasciculi, 
which  proceed  from  the  inner  side  of  the  external  malleolus,  and 
diverge  in  three  different  directions.  The  anterior  fasciculus  passes 
forwards,  and  is  attached  to  the  astragalus ;  the  posterior,  back- 
w^ards,  and  is  connected  with  the  astragalus  posteriorly;  and  the 
middle,  longer  than  the  other  two,  descends  to  be  inserted  into  the 
outer  side  of  the  os  calcis. 

"  It  is  the  strong  union  of  this  bone,"  says  Sir  Astley  Cooper,  with 
the  tarsal  bones  by  means  of  the  external  lateral  ligaments,  "  which 
leads  to  its  being  more  frequently  fractured  than  dislocated." 

The  transverse  ligament  of  the  tibia  and  fibula  occupies  the  place 
of  a  posterior  ligament.  It  is  in  relation,  behind,  with  the  posterior 
tibial  vessels  and  nerve,  and  with  the  tendon  of  the  tibialis  posticus 
muscle ;  and  in  front,  with  the  extra-synovial  adipose  tissue,  and 
synovial  membrane. 

The  Synovial  membrane  invests  the  cartilaginous  surfaces  of  the 
tibia  and  fibula,  sending  a  duplicature  upwards  between  their  lower 
ends ;  and  the  upper  surface  and  two  sides  of  the  astragalus.  It  is 
then  reflected  upon  the  anterior  and  lateral  ligaments,  and  upon  the 
transverse  ligament  posteriorly. 

Actions. — The  movements  of  the  ankle  joint  are  flexion  and  ex- 
tension only,  without  lateral  motion. 

5.  Articulation  of  the  Tarsal  Bones. — The  ligaments  which  con- 
nect the  seven  bones  of  the  tarsus  to  each  other  are  of  three  kinds, — 

Dorsal, 

Plantar, 

Interosseous. 

The  dorsal  ligaments  are  small  fasciculi  of  parallel  fibres,  which 
pass  from  each  bone  to  all  the  neighbouring  bones  with  which  it 
articulates.  The  only  dorsal  ligaments  deserving  of  particular 
mention  are,  the  external  and  posterior  calcaneo-astragaloid, 
which,  with  the  interosseous  ligament,  complete  the  articulations 
of  the  astragalus  with  the  os  calcis ;  the  superior  and  internal 
calcaneo-cuboid  ligaments ;  and  the  superior  astragalo-scaphoid 
ligament.  The  internal  calcaneo-cuboid  and  the  superior  calcaneo- 
scaphoid  ligament,  which  are  closely  united  posteriorly  in  the  deep 
groove  which  intervenes  between  the  astragalus  and  os  calcis, 
separate  anteriorly  to  reach  their  respective  bones,  and  form  the 
principal  bond  <)[  connexion  between  the  first  and  second  range  of 


TARSAL    ARTICULATIONS. 


137 


Fig.  64.* 


bones  of  the  foot.  It  is  the  division  of  this  portion  of  these  hga- 
ments  that  demands  the  especial  attention  of  the  surgeon  in  per- 
forming Chopart's  operation. 

The  plantar  ligaments  have  the  same  disposition  on  the  plantar 
surface  of  the  foot ;  three  of  them,  however,  are  of  large  size  and 
have  especial  names,  viz.  the 

Calcaneo-scaphoid, 
Long  calcaneo-cuboid, 
Short  calcaneo-cuboid. 

The  inferior  calcaneo-scaphoid  ligament  is  a  broad  and  fibro- 
cartilaginous band  of  hgament,  which  passes  for- 
wards from  the  anterior  and  inner  border  of  the  os 
calcis  to  the  edge  of  the  scaphoid  bone.  In  addition 
to  connecting  the  os  calcis  and  scaphoid,  it  sup- 
ports the  astragalus,  and  forms  part  of  the  cavity  in 
which  its  rounded  head  is  received.  It  is  Hned 
upon  its  upper  surface  by  the  synovial  membrane  of 
the  astragalo-scaphoid  articulation. 

The  firm  connexion  of  the  os  calcis  with  the 
scaphoid  bone,  and  the  feebleness  of  the  astragalo- 
scaphoid  articulation  are  conditions  favourable  to 
the  occasional  dislocation  of  the  head  of  the  astra- 
galus. 

The  long  calcaneo-cuboid,  or  ligamentum  longum 
plantcB,  is  a  long  band  of  ligamentous  fibres,  which 
proceeds  from  the  under  surface  of  the  os  calcis  to  the  rough  sur- 
face on  the  under  pai't  of  the  cuboid  bone,  its  fibres  being  continued 
onwards  to  the  bases  of  the  third  and  fourth  metatarsal  bones. 

This  ligament  forms  the  inferior  boundary  of  a  canal  in  the 
cuboid  bone,  through  which  the  tendon  of  the  peroneus  longus 
passes  to  its  insertion  into  the  base  of  the  metatarsal  bone  of  the 
great  toe. 

The  short  calcaneo-cuboid,  or  ligamentum  breve  plantcs,  is  situated 
nearer  to  the  bones  than  the  long  plantar  ligament,  from  which  it 
is  separated  by  adipose  tissue ;  it  is  broad  and  extensive,  and  ties 
the  under  surface  of  the  os  calcis  and  cuboid  bone  firmly  together. 

The  interosseous  ligaments  are  five  in  number;  they  are  short 
and  strong  ligamentous  fibres  situated  between  adjoining  bones, 
and  firmly  attached  to  their  rough  surfaces.  One  of  these,  the 
calcaneo-astragaloid,  is  lodged  in  the  groove  between  the  upper 
surface  of  the  os  calcis,  and  the  lower  of  the  astragalus.  It  is 
large  and  very  strong,  consists  of  vertical  and  oblique  fibres,  and 
serves  to  unite  the  os  calcis  and  astragalus  solidly  together.     The 


*  A  posterior  view  of  the  ankle  ioint.  1.  Tlie  lower  part  of  the  interosseous  mem- 
brane.  2.  The  posterior  inferior  ligament  connecting  the  tibia  and  fibula.  3.  The 
transverse  ligament.  4.  The  internal  lateral  ligament.  5.  The  posterior  fasciculus 
of  the  external  lateral  ligament.  G.  The  middle  fasciculus  of  the  external  ligament. 
7.  The  synovial  membrane  of  the  ankle  joint.     8.  The  os  calcis. 

18 


138 


TARSO-METATARSAL  ARTICULATION. 


Fig.  65/ 


second  interosseous  ligament,  also  very  strong,  is  situated  between 
the  sides  of  the  scaphoid  and  cuboid  bone ;  while  the  three  remain- 
ing ligaments  connect  strongly  together  the  three  cuneiform  bones 
and  the  cuboid. 

The  synovial  membranes  of  the  tarsus  are  four  in  number  ;  one, 
for  the  posterior  calcaneo-astragaloid  articulation;  a  second,  for  the 
anterior  calcaneo-astragaloid  and  astragalo-scaphoid  articulation. 
Occasionally  an  additional  small  synovial  membrane  is  found  in 
the  anterior  calcaneo-astragaloid  joint ;  a  third,  for  the  calcaneo- 
cuboid articulation ;  and  a  fourth,  the  large  tarsal  synovial  mem- 
brane for  the  articulations  between  the  scaphoid  and  three  cunei- 
form bones,  the  cuneiform  bones  with  each  other,  the  external 
cuneiform  bone  with  the  cuboid,  and  the  two  external  cuneiform 
bones  with  the  bases  of  the  second  and  third  metatarsal  bones. 
The  prolongation  which  reaches  the  metatarsal  bones  passes  for- 
wards between  the  internal  and  middle  cuneiform  bones.  A  small 
synovial  membrane  is  sometimes  met  with  between  the  contiguous 
surfaces  of  the  scaphoid  and  cuboid  bone. 

Actions. — The  movements  permitted  by  the  ar- 
ticulation between  the  astragalus  and  os  calcis,  are 
a  shght  degree  of  gliding,  in  the  directions /onoarrfs 
and  backwards  and  laterally  from  side  to  side. 
The  movements  of  the  second  range  of  tarsal 
bones  are  very  trifling,  being  greater  between  the 
scaphoid  and  three  cuneiform  bones  than  in  the 
other  articulations.  The  movements  occurring 
between  the  first  and  second  range  are  the  most 
considerable ;  they  are  adduction  and  abduction, 
and,  in  a  minor  degree,  Jlexion,  which  increases 
the  arch  of  the  foot,  and  extension,  which  flattens 
the  arch. 

6.   Tarso-metatarsal   Articulations. — The    liga- 
ments of  this  articulation  are, 
Dorsal, 
Plantar, 
Interosseous. 
The    dorsal  ligaments  connect   the  metatarsal 
to  the  tarsal  bones,  and  the  metatarsal  bones  with 
each  other. 

The  plantar  ligaments  have  the  same  disposition  on  the  plantar 
surface. 


*  The  ligaments  of  the  sole  of  the  foot.  1.  Tlic  os  calcis.  2.  The  astragalus.  3. 
The  tuberosity  of  the  scaphoid  bone.  4.  Tlic  long  calcanco-cuboid  ligament.  5  Part 
of  the  short  calcaneo-cuboid  ligament.  G.  'J'hc  calcaneo-scaphoid  ligament.  7.  The 
plantar  tarsal  ligiimcnts.  8,8.  The  tendon  of  the  peroneus  longus  muscle.  9,9.  Plantar 
tarso-motatarsa]  ligaments.  10.  Plantar  ligament  of  the  metatarso-phalangeal  articula- 
tion of  the  great  toe;  the  same  ligament  is  seen  upon  the  other  toes.  11.  Lateral 
ligaments  of  tiie  metiilarso-jjhalangeal  articulation.  12.  Transverse  ligament.  13. 
The  lateral  ligaments  of  the  phalanges  of  the  great  toe ;  the  same  ligaments  are  seen 
upon  the  other  toes. 


METATARSO-PHALANGEAL  ARTICULATION.  139 

The  interosseous  ligaments  are  situated  between  the  bases  of  the 
metatarsal  bones  of  the  four  lesser  toes,  and  also  between  the  base 
of  the  second  metatarsal  bone,  and  the  internal  and  external  cunei- 
form bone. 

The  metatarsal  bone  of  the  second  toe  is  implanted  by  its  base 
between  the  internal  and  external  cuneiform  bones,  and  is  the  most 
strongly  articulated  of  all  the  metatarsal  bones.  This  disposition 
must  be  recollected  in  amputation  at  the  tarso-metatarsal  articula- 
tion. 

The  synovial  membranes  of  this  articulation  are  three  in  number : 
one  for  the  metatarsal  bone  of  the  great  toe ;  one  for  the  second  and 
third  metatarsal  bones,  which  is  continuous  with  the  great  tarsal 
synovial  membrane ;  and  one  for  the  fourth  and  fifth  metatarsal 
bones. 

Actions. — The  movements  of  the  metatarsal  bones  upon  the  tarsal, 
and  upon  each  other  are  very  slight;  they  are  such  only  as  contri- 
bute to  the  strength  of  the  foot  by  permitting  a  certain  degree  of 
yielding  to  opposing  forces. 

7.  Metatarso-phalangeal  Articulation. — The  ligaments  of  this  ar- 
ticulation, like  those  of  the  articulation  between  the  first  phalanges 
and  metacarpal  bones  of  the  hand,  are. 

Anterior  or  plantar. 
Two  lateral, 
Transverse. 

The  anterior  or  plantar  ligaments  are  thick  and  fibro-cartilagi- 
nous,  and  form  part  of  the  articulating  surface  of  the  joint. 

The  lateral  ligaments  are  short  and  very  strong,  and  situated  on 
each  side  of  the  joints. 

The  transverse  ligaments  are  strong  bands,  which  pass  trans- 
versely between  the  anterior  ligaments. 

The  expansion  of  the  extensor  tendon  supplies  the  place  of  a  dor- 
sal ligament. 

Actions. — The  movements  of  the  first  phalanges  upon  the  rounded 
heads  of  the  metatarsal  bones,  are  Jlexion,  extension,  adduction  and 
abduction. 

8.  Articulation  of  the  Phalanges. — The  ligaments  of  the  phalanges 
are  the  same  as  those  of  the  fingers,  and  have  the  same  disposition; 
their  actions  are  also  similar.     They  are, 

Anterior  or  plantar, 
Two  lateral. 


CHAPTER      III. 

ON  THE  MUSCLES. 

Muscles  are  the  moving  organs  of  the  animal  frame :  they  con- 
stitute by  their  size  and  number  the  great  bulk  of  the  body,  upon 
which  they  bestow  form  and  symmetry.  In  the  limbs  they  are  situated 
around  the  bones,  which  they  invest  and  defend,  while  they  form  to 
some  of  the  joints  a  principal  protection.  In  the  trunk  they  are  spread 
outto  enclose  cavities,  and  constitute  a  defensive  wall  capable  of  yield- 
ing to  internal  pressure,  and  again  returning  to  its  original  form. 

Their  colour  presents  the  deep  red  which  is  characteristic  of 
flesh,  and  their  form  is  variously  modified,  to  execute  the  varied 
range  of  movements  which  they  are  required  to  effect. 

Muscle  is  composed  of  a  number  of  parallel  fibres  placed  side  by 
side,  and  supported  and  held  together  by  a  delicate  web  of 
cellular  tissue  ;  so,  that  if  it  were  possible  to  remove  the  muscular 
substance,  we  should  have  remaining  a  beautiful  cellular  frame- 
work, possessing  the  exact  form  and  size  of  the  muscle  without  its 
colour  and  soUdity.  Towards  the  extremity  of  the  organ  the  mus- 
cular fibre  ceases,  and  the  cellular  structure  becomes  aggregated 
and  modified,  so  as  to  constitute  those  glistening  fibres  and  cords 
by  which  the  muscle  is  tied  to  the  surface  of  bone,  and  which  are 
called  tendons.  Almost  every  muscle  in  the  body  is  connected 
with  bone,  either  by  tendinous  fibres,  or  by  an  aggregation  of  those 
fibres  constituting  a  tendon ;  and  the  union  is  so  firm,  that,  under 
extreme  violence,  the  bone  itself  rather  breaks  than  permits  of  the 
separation  #f  the  tendon  from  its  attachment.  In  the  broad  muscles 
the  tendon  is  spread  so  as  to  form  an  expansion,  called  aponeurosis 
(atfo,  long ;  vsugov*  nervus — a  nerve  widely  spread  out). 

Muscles  present  various  modifications  in  the  arrangement  of  their 
fibres  in  relation  to  their  tendinous  structure.  Sometimes  they  are 
completely  longitudinal,  and  terminate  at  each  extremity  in  tendon, 
the  entire  muscle  being  fusiform  in  its  shape ;  in  other  situations 
they  are  disposed  like  the  rays  of  a  fan,  converging  to  a  tendinous 
point,  as  the  temporal,  pectoral,  glutei,  &c.,  and  constitute  a  radiate 
muscle.  Again,  they  are  penniform,  converging  like  the  plumes  of 
a  pen  to  one  side  of  a  tendon  which  runs  the  whole  length  of  the 
muscle,  as  in  the  peronei ;  or  bipenniform,  converging  to  both  sides 
of  the  tendon.  In  other  muscles  the  fibres  pass  obliquely  from  the 
surface  of  a  tendinous  expansion  spread  out  on  one  side,  to  that  of 
another  extended  on  the  opposite  side,  as  in  the  semi-membranosus ; 
or  they  arc  composed  of  penniform  or  bipenniform  fasciculi  as  in  the 
deltoid,  and  constitute  a  compound  muscle. 

The  nomenclature  of  the  muscles  is  defective  and  confused,  and 
is  generally  derived  from  some  prominent  character  which  each 

*  The  ancients  named  all  the  white  fibres  of  the  body  v««ga ;  the  term  has  since  been 
limited  to  the  nervoB. 


STRUCTURE  OP  MUSCLE. 


141 


muscle  presents  :  thus,  some  are  named  from  their  situation,  as  the 
tibialis,  pei'oneus ;  others  from  their  uses,  as  the  flexors,  extensors, 
adductors,  abductors,  levators,  tensors,  &c.  Some  again  from  their 
form,  as  the  trapezius,  triangularis,  deltoid,  &c.;  and  others  from 
their  direction,  as  the  rectus,  obliquus,  transversalis,  &c.  Some 
muscles  have  received  names  expressive  of  their  attachments,  as  the 
sterno-mastoid,  sterno-hyoid,  &c. ;  and  others,  of  their  divisions,  as 
the  biceps,  triceps,  digastricus,  complexus,  &c. 

In  the  description  of  a  muscle 
we   express  its  attachment  by  Fig.  66.* 

the  vv^ords  "  origin"  and  "  inser- 
tion;" the  term  or?^m  being  gene- 
rally applied  to  the  more  fixed 
or  central  attachment,  or  to  the 
point  towards  which  the  motion 
is  directed,  while  insertion  is  as- 
signed to  the  more  movable  point, 
or  to  that,  most  distant  from  the 
centre ;  but  there  are  many  ex- 
ceptions to  this  principle,  and 
as  many  muscles  pull  equally 
by  both  extremities,  the  use  of 
such  terms  must  be  regarded  as  purely  arbitrary. 

In  structure,  muscle  is  composed  of  bundles  of  fibres  of  variable 
size  called  fasciculi,  which  are  enclosed  in  a  cellular  membranous 
investment  or  sheath,  and  the  latter  is  continuous  with  the  cellular 
framework  of  the  fibres.  Each  fasciculus  is  composed  of  a  number 
of  smaller  bundles,  and  these  of  single  fibres,  which,  from  their  minute 
size  and  independent  appearance,  have  been  distinguished  by  the 
name  of  ultimate  fibres.  The  ultimate  fibre  is  found  by  microsco- 
pic investigation,  to  be  itself  made  up  of  a  number  of  ultimate  fibrils 
enclosed  in  a  delicate  sheath  or  myolemma.f  Two  kinds  of  ulti- 
mate muscular  fibre  exist  in  the  animal  economy ;  viz.,  that  of 
voluntary  or  animal  life,  and  that  of  involuntary  or  organic  life. 

*  A.  A  muscular  fibre  of  animal  life  enclosed  in  its  myolemma ;  the  transverse  and 
longitudinal  striae  are  seen. 

B,  An  ultimate  fibril  of  muscular  fibre  of  animal  life. 

c.  A  muscular  fibre  of  animal  life,  similar  to  a  but  more  highly  magnified.  Its 
myolemma  is  so  thin  and  transparent  as  to  permit  the  ultimate  fibrils  to  be  seen  through. 
The  true  nature  of  the  longitudinal  striae  is  seen  in  this  fibre  as  well  as  the  mode  of  for- 
mation of  the  transverse  striae. 

D.  A  muscular  fibre  of  organic  life  from  the  urinary  bladder,  magnified  600  times, 
linear  measure.     Two  of  the  nuclei  are  seen. 

E,  A  muscular  fibre  of  organic  life,  from  the  stomach,  magnified  600  times.  The 
diameter  of  this  and  of  the  preceding  fibre,  midway  between  the  nuclei,  was  1 -4750th 
of  an  inch. 

t  In  the  summer  of  1836,  while  engaged  with  Dr.  Jones  Quain  in  the  examination 
of  the  animal  tissues  with  a  simple  dissecting  microscope,  constructed  by  Powell,  I 
first  saw  that  the  ultimate  fibre  of  muscle  was  invested  by  a  proper  slieatli,  for  which 
I  proposed  the  term  "  Myolemma ;"  a  term  which  was  adopted  by  Dr.  Quain  in  the 
fourth  edition  of  his  "  Elements  of  Anatomy."  We  at  that  time  believed  that  the  trans- 
verse folding  of  that  sheath  gave  rise  to  the  appearance  of  transverse  striae,  an  opinion 
which  subsequent  examinations  proved  to  be  incorrect,  Mr.  Bowman  employs  the 
term  "  Sarcolemma"  as  synonymous  with  Myolemma. 


142 


STRUCTURE  OF  MUSCLE. 


The  -fibre  of  animal  life  is  recognised  from  being  marked  by 
transverse  and  slightly  waving  striae.  The  fibre  of  organic  life  has 
no  transverse  stride,  and  is  much  smaller  than  the  fibre  of  animal 
life.  It  is  polygonal  in  form  or  nearly  cylindrical,  and  appears  to 
consist  of  a  number  of  minute  parallel  filaments  enclosed  in  a  myo- 
lemma.  The  most  remarkable  character  of  the  organic  fibre  is  the 
existence  from  point  to  point  of  swellings  somewhat  larger  than  the 
diameter  of  the  fibre,  and  produced  by  the  nuclei  of  the  original 
nucleated  cells  from  which  the  fibre  was  developed. 

The  ultimate  fibrils  are  minute  beaded  filaments  in  the  fibre  of 
animal  life,  and  cylindrical  and  uniform  in  the  organic  fibre. 

According  to  the  researches  of  Mr.  Bowman*  the  ultimate  fibres 
(primitive  fasciculi)  are  polygonal,  a  form  which  is  well  suited  to 
admit  of  their  being  collected  into  bundles.  In  size  they  are  very 
variable,  not  only  in  the  different  classes  and  genera  of  animals, 
but  also  in  the  same  animal  and  even  in  the  same  muscle.  He 
has  observed,  moreover,  that  they  are  somewhat  smaller  in  the 
female  than  in  the  male ;  thus  the  average  diameter  of  the  ultimate 
fibre  in  the  female,  is  ^-i^;  in  the  male  ^i^;  the  average  of 
both  being  -^i-j.  In  the  different  classes  of  animals  examined 
by  Mr.   Bowman,   the   largest    ultimate   fibre  was   met  with  in 

fishes,  in  which  the  average  diameter 
is  2 1 2- '  ^6^t  in  man  ;  and  then  in  other 
classes  in  the  following  order :  insects, 
■^\-g',  reptiles,  ^^;  mammalia,  ^i-^ ; 
birds,  ^iy. 

The  ultimate  fibrils  (primitive  fibrillse) 
consist  of  segments  separated  from 
each  other  by  constrictions,  which 
give  to  the  entire  fibril  the  appearance 
of  a  string  of  beads.  The  constric- 
tions are  narrower  than  the  segments, 
and  their  component  substance  is  pro- 
bably less  dense  than  that  which  forms 
the  segments.  An  ultimate  fibre  con- 
sists of  a  bundle  of  fibrils,  which  are  so 
disposed  that  all  the  segments  and  all 
the  constrictions  correspond,  and  these 
give  rise  to  the  alternate  light  and  dark 
lines  of  the  transverse  strise.f  The 
fibrils  are  connected  together  with  very 
different  degrees  of  closeness  in  different 

*  On  the  Minute  Structure  and  Movements  of  Voluntary  Muscle,  By  Wm.  Bow- 
man, Esq.     From  the  Philosophical  Transactions  for  1840. 

F.  Transverse  section  of  ultimate  fibres  of  the  biceps,  copied  from  the  illustrations 
to  Mr.  Bowman's  paper.  In  this  figure  the  polygonal  form  of  the  fibres  is  seen,  and 
their  composition  of  ultimate  fibrils. 

G.  An  ultimate  fibre,  in  which  ihc  transverse  splitting  into  discs,  in  the  direction  of 
the  constrictions  of  the  ultimate  fibrils  is  seen.     From  Mr.  Bowman's  paper. 

t  According  to  (Jerhr.r  the  transverse  strise  on  the  ultimate  fibres  are  produced  by  a 
delicate  thread  of  cellular  tissue  wound  spirally  around  the  ultimate  fibrils  so  as  to 
hold  tlicrn  in  a  bundle,  and  my  own  observations  corroborate  his,  G, 


STRUCTURE  OF  MUSCLE,  143 

animals ;  in  man  they  are  but  slightly  adherent,  and  distinct  lon- 
gitudinal lines  of  junction  may  be  observed  between  them, — they 
also  separate  very  easily  when  macerated  for  some  time.  Besides 
the  more  usual  separation  of  the  ultimate  fibre  into  fibrils,  it  breaks, 
when  stretched,  into  transverse  sections,  corresponding  with  the 
dark  line  of  the  strias,  and  consequently  with  the  constrictions  of 
the  fibrillae.  When  this  division  occurs  with  the  greatest  facility, 
the  longitudinal  lines  are  indistinct  or  scarcely  perceptible.  "  In 
fact,"  says  Mr.  Bowman,  "  the  primitive  fasciculus  seems  to  consist 
of  primitive  component  segments  or  particles,  arranged  so  as  to 
form,  in  one  sense,  fibrillae,  and  in  another  sense,  discs  ;  and  which 
of  these  two  may  happen  to  present  themselves  to  the  observer,  will 
depend  on  the  amount  of  adhesion,  endways  or  sideways,  existing 
between  the  segments.  Generally,  in  a  recent  fasciculus,  there  are 
transverse  striae,  showing  divisions  into  discs,  and  longitudinal 
striae,  marking  its  composition  by  fibrillae." 

Mr.  Bowman  has  observed  that  in  the  substance  of  the  ultimate 
fibre  there  exist  minute  "  oval  or  circular 
discs,  frequently  concave  on  one  or  both 
surfaces,    and    containing,    somewhere  ^ 

near  the  centre,  one,  two  or  three  minute       ^^=^  _gi^^-Z^^^" 
dots   or  granules."     Occasionally   they        ~=3;;;;z^^^^^'^^^^ 
are  seen  to  present  irregularities  of  form,      i^^^g-^^^^^=-^ 
which  Mr.  Bowman  is  inclined  to  regard     J^^^^^^^^^T^]^^ 
as  accidental.     They   are   situated  be-    -'^jg=r:-"^^_~I!^"^=- 
tween,    and   are    connected    with    the     ^^^    -,=  -  \^^^s 
fibrils,    and    are    distributed    in    pretty      -^^^^^^^^^J' 
equal  numbers  through  the  fibre.    These 
corpuscles  are  the  nuclei  of  the  nucle- 
ated cells  from  which  the  muscular  fibre  was  originally  developed. 
From   observing,  however,   that   their   "absolute   number   is    far 
greater  in  the  adult  than  in  the  foetus,  while  their  number,  rela- 
tively to  the  bulk  of  the  fasciculi,  at  these   two  epochs,  remains 
nearly  the  same,"  Mr.  Bowman  regards  it  as  certain,  that  "  during 
developement,  and  subsequently,  a  further  and  successive  deposit  of 
corpuscles"  takes  place.     The  corpuscles  are  only  brought  into 
view  when  the  muscular  fibre  is  acted  upon  by  a  solution  of  "  one 
of  the  milder  acids,  as  the  citric." 

Muscles  are  divided  into  two  great  classes,  voluntary  and 
involuntary,  to  which  may  be  added  as  an  intermediate  and  con- 
necting link,  the  muscle  of  the  vascular  system,  the  heart. 

The  voluntary,  or  system  of  animal  life,  is  developed  from  the 
external  or  serous  layer  of  Ihe  germinal  membrane,  and  compre- 
hends the  whole  of  the  muscles  of  the  limbs  and  of  the  trunk.  The 
involuntary  or  organic  system  is  developed  from  the  internal  or 
mucous  layer,  and  constitutes  the  thin  muscular  structure  of  the 

H.  Mass  of  ultimate  fibres  from  tlie  pectoralis  major  of  the  human  foetus,  at  nine 
months,  Tliese  fibres  have  been  immersed  in  a  solution  of  tartaric  acid,  and  their 
"  numerous  corpuscules,  turned  in  various  directions,  some  presenting  nucleoli,"  are 
shewn.     From  Mr.  Bowman's  paper. 


144  HUSCLES  OF  THE  HEAD  AND  NECK. 

intestinal  canal,  bladder,  and  internal  organs  of  generation.  At  the 
commencement  of  the  aUmentary  canal  in  the  oesophagus,  and 
near  its  termination  in  the  rectum,  the  muscular  coat  is  formed  by 
a  blending  of  the  fibres  of  both  classes.  The  heart  is  developed 
from  the  middle,  or  vascular  layer  of  the  germinal  membrane ;  and 
although  involuntary  in  its  action,  is  composed  of  ultimate  fibres 
havdng  the  transverse  striae  of  the  muscle  of  animal  life. 

The  muscles  may  be  arranged  in  conformity  with  the  general 
division  of  the  body  into, — 1.  Those  of  the  head  and  neck.  2. 
Those  of  the  trunk.  3.  Those  of  the  upper  extremity.  4.  Those 
of  the  lower  extremity. 

1.    MUSCLES  OF  THE  HEAD  AND  NECK. 

The  muscles  of  the  head  and  neck  admit  of  a  subdivision  into 
those  of  the  head  and  face,  and  those  of  the  neck. 

Muscles  of  the  Head  and  Face. — These  muscles  may  be  divided 
into  groups  corresponding  with  the  natural  regions  of  the  head  and 
face  ;  the  groups  are  eight  in  number,  viz. — 

1 .  Cranial  group.  5.  Superior  labial  group. 

2.  Orbital  group.  6.  Inferior  labial  group. 

3.  Ocular  group.  7.  Maxillary  group. 

4.  Nasal  group.  8.  Auricular  group. 

The  muscles  of  each  of  these  groups  may  be  thus  arranged — 

1.  Cranial  growp.  Levator    labii    superioris    pro- 
Occipito-frontalis.  prius, 

_.    ^  , .    ,  Levator  anguli  oris, 

2.  Orbital  group.  Zygomaticus  major, 

Orbicularis  palpebrarum,  Zygomaticus  minor, 

Corrugator  supercilii.  Depressor  labii  superioris  alse- 

Tensor  tarsi.  que  nasi. 

3.  Ocular  growp.  6.  Inferior  labial  group. 
Levator  palpebral,  (Orbicularis  oris),* 
Rectus  superior.  Depressor  labii  inferioris, 
Rectus  inferior.  Depressor  anguli  oris, 
Rectus  internus.  Levator  labii  inferioris. 
Rectus  externus,  „    n/r     -n 

Obliquus  superior,  ^'  ^^^^^^^ry  group. 

Obiiquus  inferior.  Masseter, 

.     ,,      ,  Temporalis, 

4.  Nasal  group.  Buccinator, 

Pyramidalis  nasi,  Pterygoideus  externus, 

Compressor  nasi.  Pterygoideus  internus. 

5.  Superior  labial  group.  8.  Auricular  group. 
(Orbicularis  oris),                            Attolens  aurem. 
Levator  labii  superioris  alsequc     Attrahcns  aurem, 

nasi,  Rctrahcns  aurem. 

*  The  orbicularis  oris,  from  encircling  llic  mouth,  belongs  necessarily  to  both  the 
superior  and  inferior  labial  regions ;  it  is  therefore  enclosed  within  brackets  in  both. 


OCCIPITO-FRONTALIS. 


145 


Fig.  68* 


Dissection. — The  occipito-frontalis  is  to  be  dissected  by  making  a 
longitudinal  incision  along  the  vertex  of  the  head,  from  the  tubercle 
on  the  occipital  bone  to  the  root  of  the  nose ;  and  a  second  incision 
along  the  forehead  and  around  the  side  of  the  head,  to  join  the  two 
extremities  of  the  preceding.  Dissect  the  integument  and  superficial 
fascia  carefully  outwards,  beginning  at  the  anterior  angle  of  the 
flap,  where  the  muscular  fibres  are  thickest,  and  remove  it  alto- 
gether. This  dissection  requires  care ;  for  the  muscle  is  very  thin, 
and  without  attention  would  be  raised  with  the  integument.  There 
is  no  deep  fascia  on  the  face  and  head,  nor  is  it  required ;  for  here 
the  muscles  are  closely  applied  against  the  bones  upon  which  they 
depend  for  support,  whilst  in  the  extremities  the  support  is  derived 
from  the  dense  layer  of  fascia  by  which  they  are  invested,  and 
which  forms  for  each  a  distinct  sheath. 

The  occipito  frontalis  is  a  broad 
musculo-tendinous  layer,  which 
covers  the  whole  of  one  side  of 
the  vertex  of  the  skull,  from  the 
occiput  to  the  eyebrow.  It  arises 
by  tendinous  fibres  from  the 
outer  two-thirds  of  the  superior 
curved  line  of  the  occipital  bone, 
and  from  the  mastoid  portion  of 
the  temporal;  it  is  inserted  into 
the  orbicularis  palpebrarum  muscle 
and  the  internal  angular  process 
of  the  frontal  bone.  The  muscle 
is  fleshy  in  front  over  the  frontal 
bone  and  behind  over  the  occipi- 
tal, the  portions  being  connected 
by  a  broad  aponeurosis.  The  two 
muscles  cover  the  whole  of  the 
vertex  of  the  skull,  hence  their 
designation  galea  capitis ;  they  are 

loosely  adherent  to   the  pericranium,  but  very  closely  to  the  in- 
tegument, particularly  over  the  forehead. 

*  The  muscles  of  the  head  and  face.  1.  The  frontal  portion  of  the  occipito-frontalis. 
2.  Its  occipital  portion.  3.  Its  aponeurosis.  4.  The  orbicularis  palpebrarum,  which 
conceals  the  corrugator  supercilii  and  tensor  tarsi.  5.  The  pyramidalis  nasi.  6.  The 
compressor  nasi.  7.  The  orbicularis  oris.  8.  The  levator  labii  superioris  alajque  nasi. 
The  figure  is  placed  on  the  nasal  portion.  9.  The  levator  labii  superioris  proprius ; 
the  lower  part  of  the  levator  anguli  oris  is  seen  between  the  muscles  10  and  11.  10. 
The  zygomaticus  minor.  11.  The  zygomaticus  major.  12.  The  depressor  labii  infe- 
rioris.  13.  The  depressor  anguli  oris.  14.  The  levator  labii  inferioris.  15.  The  su- 
perficial portion  of  the  masseter.  16.  Its  deep  portion.  17.  The  attrahens  aurem.  18. 
The  buccinator.  19.  The  attolens  aurem.  20.  The  temporal  fascia  which  covers  in 
the  temporal  muscle.  21.  The  retrahens  aurem.  22.  The  anterior  belly  of  the  digas- 
tricus  muscle  ;  tlie  tendon  is  seen  passing  tln-ough  its  aponeurotic  pulley.  23.  The 
stylo-hyoid  muscle  pierced  by  the  posterior  belly  of  the  digastricus.  24.  The  mylo- 
hyoideus  muscle.  25.  The  upper  part  of  the  sterno-mastoid.  26.  The  upper  part  of  the 
trapezius.    The  muscle  between  25  and  26  is  the  splenius. 

19 


146  ORBITAL  GROUP. 

Relations. — This  muscle  is  in  relation  by  its  external  surface  from 
before  backwards,  with  the  frontal  and  supra-orbital  vessels,  the 
supra-orbital  and  facial  nerve,  the  temporal  vessels  and  nerve,  the 
occipital  vessels  and  nerves,  and  with  the  integument,  to  which  it 
is  very  closely  adherent.  Its  under  surface  is  attached  to  the  peri- 
cranium by  a  loose  cellular  tissue  which  admits  of  considerable 
movement. 

Action. — To  raise  the  eyebrows,  thereby  throwing  the  integument 
of  the  forehead  into  transverse  wrinkles.  Some  persons  have  the 
power  of  moving  the  entire  scalp  upon  the  pericranium  by  means 
of  these  muscles. 

Dissection. — The  dissection  of  the  face  is  to  be  effected  by  con- 
tinuing the  longitudinal  incision  of  the  vertex  of  the  previous  dis- 
section onwards  to  the  tip  of  the  nose,  and  thence  downwards  to  the 
margin  of  the  upper  lip  ;  then  carry  an  incision  along  the  margin 
of  the  lip  to  the  angle  of  the  mouth,  and  transversely  across  the 
face  to  the  angle  of  the  lower  jaw.  Lastly,  divide  the  integument 
in  front  of  the  external  ear  upwards  to  the  transverse  incision 
which  was  made  for  exposing  the  occipito-frontalis.  Dissect  the 
integument  and  superficial  fascia  carefully  from  the  whole  of  the 
region  included  by  these  incisions,  and  the  three  next  groups  of 
muscles  will  be  brought  into  view. 

2.  Orbital  growp. — Orbicularis  palpebrarum, 
Corrugator  supercilii, 
Tensor  tarsi. 

The  orbicularis  palpebrarum  is  a  sphincter  muscle,  surrounding 
the  orbit  and  eyelids.  It  arises  from  the  internal  angular  process 
of  the  frontal  bone,  from  the  nasal  process  of  the  superior  maxillary, 
and  from  a  short  tendon  {tendo  oculi)  which  extends  between  the 
nasal  process  of  the  superior  maxillary  bone,  and  the  inner  ex- 
tremities of  the  tarsal  cartilages  of  the  eyelids.  The  fibres  encircle 
the  orbit  and  eyelids,  forming  a  broad  and  thin  muscular  plane, 
which  is  inserted  into  the  lower  border  of  the  tendo  oculi  and  into 
the  nasal  process  of  the  superior  maxillary  bone.  Upon  the  eyelids 
the  fibres  are  very  thin  and  pale,  and  possess  an  involuntary  action. 
The  tendo  oculi,  in  addition  to  its  insertion  into  the  nasal  process  of 
the  superior  maxillary  bone,  sends  a  process  inwards  which  expands 
over  the  lachrymal  sac,  and  is  attached  to  the  ridge  of  the  lachry- 
mal bone ;  this  is  the  reflected  aponeurosis  of  the  tendo  oculi. 

Relations. — By  its  superficial  surface  it  is  closely  adherent  to  the 
integument,  from  which  it  is  separated  over  the  eyelids  by  a  loose 
serous  cellular  tissue.  By  its  deep  surface  it  lies  in  contact  above 
with  the  upper  border  of  the  orbit,  with  the  corrugator  supercilii 
muscle,  and  with  the  frontal  and  supra-orbital  vessels  and  supra- 
orbital nerve ;  below,  with  the  lachrymal  sac,  with  the  origins  of 
the  labii  supcrioris  ateque  nasi,  levator  labii  supcrioris  proprius, 


OCULAR  GROUP.  147 

zygomaticus  major  and  minor  muscles,  and  malar  bone  ;  and  exter- 
nally with  the  temporal  fascia.  Upon  the  eyelid  it  is  in  relation 
with  the  broad  tarsal  ligament  and  tarsal  cartilages,  and  by  its  upper 
border  gives  attachment  to  the  occipito-frontalis  muscle. 

The  corrugator  sicpsrcilii  is  a  small  narrow  and  pointed  muscle, 
situated  immediately  above  the  orbit  and  beneath  the  upper  segment 
of  the  orbicularis  palpebrarum  muscle.  It  caises  from  the  inner  ex- 
tremity of  the  superciliary  ridge  and  is  inserted  into  the  under 
^  surface  of  the  orbicularis  palpebrarum. 

Relations. — By  its  supefficial  surface,  with  the  pyramidalis  nasi, 
occipito-frontahs  and  orbicularis  palpebrarum  muscle ;  and  by  its 
deej)  surface  with  the  supra-orbital  vessels  and  nerve. 

The  tensor  tarsi  (Horner's*  muscle)  is  a  thin  plane  of  muscular 
fibres,  about  three  lines  in  breadth  and  six  in  length.  It  is  best  dis- 
sected by  separating  the  eyelids  of  the  eye,  and  turning  them  over 
the  nose  without  disturbing  the  tendo  oculi ;  then  dissect  away  the 
small  fold  of  mucous  membrane  called  plica  semilunaris,  and  some 
loose  cellular  tissue  under  which  the  muscle  is  concealed.  It  arises 
from  the  orbital  surface  of  the  lachrymal  bone,  and  passing  across 
the  lachrymal  sac  divides  into  two  slips,  which  are  inserted  into  the 
lachrymal  canals  as  far  as  the  puncta. 

Actions. — The  palpebral  portion  of  the  orbicularis  acts  involun- 
tarily in  closing  the  lids,  and  from  the  greater  curve  of  the  upper 
lid,  upon  that  principally.  The  entire  muscle  acts  as  a  sphincter, 
drawing  at  the  same  time,  by  means  of  its  osseous  attachment,  the 
integument  and  Uds  inwards  towards  the  nose.  The  corrugatores 
superciliorum  draw  the  eyebrows  downwards  and  inwards,  and 
produce  the  vertical  wrinkles  of  the  forehead.  The  tensor  tarsi,  or 
lachrymal  muscle,  draws  the  extremities  of  the  lachrymal  canals 
inwards,  so  as  to  place  the  puncta  in  the  best  position  for  receiving 
the  tears.  It  serves  also  to  keep  the  lids  in  relation  with  the  surface 
of  the  eye,  and  compresses  the  lachrymal  sac.  Dr.  Horner  is  ac- 
quainted with  two  persons  who  have  the  voluntary  power  of  draw- 
ing the  lids  inwards  by  these  muscles  so  as  to  bury  the  puncta  in 
the  angle  of  the  eye. 

3.  Ocular  group. — Levator  palpebrge. 
Rectus  superior. 
Rectus  inferior. 
Rectus  internus, 
Rectus  externus. 
Obliquus  superior, 
Obliquus  inferior. 

Dissection. — To  open  the  orbit  (the  calvarium  and  brain  havino- 
been  removed)  the  frontal  bone  must  be  sawn  through  at  the  inner 
extremity  of  the  orbital  ridge  ;  and,  externally,  at  its  outer  extremity. 

J*  W.  E.  Horner,  M.D.,  Professor  of  Anatomy  in  the  University  of  Pennsylvania. 
*rhe  notice  of  this  discovery  is  contained  in  a  work  published  in  Philadelphia  in  1827, 
entitled  "  Lessons  in  Practical  Anatomy." 


148  OCULAR  GROUP. 

The  roof  of  the  orbit  may  then  be  comminuted  by  a  few  hght  blows 
with  the  hammer ;  a  process  easily  accomplished,  on  account  of  the 
thinness  of  the  orbital  plate  of  the  frontal  bone  and  lesser  wing  of 
the  sphenoid.  The  superciliary  portion  of  the  orbit  may  now  be 
driven  forwards  by  a  smart  blow,  and  the  broken  fragments  of  the 
roof  of  the  orbit  removed.  The  periosteum  will  then  be  exposed 
unbroken  and  undisturbed.  Remove  the  periosteum  from  the  whole 
of  the  upper  surface  of  the  exposed  orbit,  and  the  muscles  may  then 
be  examined. 

The  levator  palpebrcB  is  a  long,  thin,  and  triangular  muscle ;  it 

arises  from  the  upper  margin  of 

Fig.  69.*  the  optic  foramen,  and  from  the 

^^^^.^^  fibrous  sheath  of  the  optic  nerve, 

^^;:::;^^^'    and   is   inserted   into   the  upper 

^^^^^^i^c,  border    of   the    superior    tarsal 

-^^^^^^^^^^^^j\  Relations. — By  its  upper  surface 

''^''\-'^^^^^^^^m^ %  m  with  the  fourth  nerve  the  supra- 

•■<2;^?"^s^^^^^^O^  7  orbital  nerve  and  artery,  the  peri- 

^^^^^^^^^  osteum  of  the  orbit,  and  in  front 

with  the  broad  tarsal  ligament.  By 

its  under  surface  it  rests  upon  the  superior  rectus  muscle,  and  the 

globe  of  the  eye ;  it  receives  its  nerve  and  artery  by  this  aspect, 

and  in  front  is  lined  for  a  short  distance  by  the  conjunctiva. 

The  rectus  superior  (attollens)  arises  from  the  upper  margin  of  the 
optic  foramen,  and  from  the  fibrous  sheath  of  the  optic  nerve,  and  is 
inserted  into  the  upper  surface  of  the  globe  of  the  eye  at  a  point 
somewhat  more  than  three  lines  from  the  margin  of  the  cornea. 

Relations. — By  its  upper  surface^Nii\i  the  levator palpebrse  muscle; 
and  by  the  iinder  surface  with  the  optic  nerve,  the  ophthalmic  artery 
and  nasal  nerve,  from  which  it  is  separated  by  a  layer  of  fascia  and 
by  the  adipose  tissue  of  the  orbit,  and  in  front  with  the  globe  of  the 
eye,  the  tendon  of  the  superior  oblique  muscle  being  interposed. 

The  rectus  inferior  (depressor)  arises  from  the  inferior  margin 
of  the  optic  foramen  by  a  tendon  (ligament  of  Zinn)  which  is 
common  to  it,  the  internal  and  the  external  rectus,  and  from  the 
fibrous  sheath  of  the  optic  nerve  ;  it  is  inserted  into  the  inferior  sur- 
face of  the  globe  of  the  eye  at  a  little  more  than  two  lines  from  the 
margin  of  the  cornea. 

Relations. — By  its  upper  surface  with  the  optic  nerve,  the  infe- 

*  The  muscles  of  the  eyeball ;  the  view  is  taken  from  the  outer  side  of  the  right 
orbit.  1.  A  small  fragment  of  the  sphenoid  hone  around  the  entrance  of  the  optic 
nerve  into  the  orbit,  y.  The  optic  nerve.  .3.  The  glol)e  of  the  eye.  4.  The  levator 
palpebrtc  muscle.  .'5.  The  superior  oblique  muscle.  6.  Its  cartilaginous  pulley.  7.  Its 
reflected  tendon.  8.  The  inferior  oblifiuo  muscle,  the  small  square  knob  at  its  com- 
mencement is  a  piece  of  its  bony  origin  broken  off.  9.  The  superior  rectus.  10.  The 
internal  rectus  ahnost  concealed  by  the  optic  nerve.  11.  Part  of  the  external  rectus, 
shovfing  its  two  heads  of  origin.  19.  The  extremity  of  the  external  rectus  at  its  in- 
sertion ;  the  intermediate  portion  of  tlie  muscle  having  been  removed.  13.  The  inferior 
rectus,  H.  The  tunica  albuginca,  formed  l)y  the  expansion  of  the  tendons  of  the  fbu^ 
recti. 


RECTI  OBLIQUI.  149 

rior  oblique  branch  of  the  third  nerve,  the  adipose  tissue  of  the 
orbit,  and  the  under  surface  of  the  globe  of  the  eye.  By  its  under 
surface  with  the  periosteum  of  the  floor  of  the  orbit,  and  with  the 
inferior  oblique  muscle. 

The  rectus  internus  (adductor),  the  thickest  and  shortest  of  the 
straight  muscles,  arises  from  the  common  tendon,  and  from  the 
fibrous  sheath  of  the  optic  nerve ;  and  is  inserted  into  the  inner 
surface  of  the  globe  of  the  eye  at  two  lines  from  the  margin  of  the 
cornea. 

Relations. — By  its  internal  surface  with  the  optic  nerve,  the  adi- 
pose tissue  of  the  orbit  and  the  eyeball.  By  its  outer  surface  with 
the  periosteum  of  the  orbit ;  and  by  its  upper  border  with  the  ante- 
rior and  posterior  ethmoidal  vessels,  the  nasal  and  supra-trochlear 
nerve. 

The  rectus  externus  (abductor),  the  longest  of  the  straight  mus- 
cles, arises  by  two  distinct  heads,  one  from  the  common  tendon,  the 
other  with  the  origin  of  the  superior  rectus  from  the  margin  of  the 
optic  foramen  ;  the  nasal,  third  and  sixth  nerves  passing  between  its 
heads.  It  is  inserted  into  the  outer  surface  of  the  globe  of  the  eye  at 
a  little  more  than  two  hnes  from  the  margin  of  the  cornea. 

Relations. — By  its  internal  surface  with  the  third,  the  nasal,  the 
sixth,  and  the  optic  nerve,  the  ciliary  ganglion  and  nerves,  the  oph- 
thalmic artery  and  vein,  the  adipose  tissue  of  the  orbit,  the  inferior 
oblique  muscle,  and  the  eyeball.  By  its  external  surface  with  the 
periosteum  of  the  orbit ;  and  by  the  wpper  border  with  the  lach- 
rymal vessels  and  nerve  and  the  lachrymal  gland. 

The  recti  muscles  present  several  characters  which  are  common 
to  all :  thus,  they  are  thin,  have  the  form  of  an  isosceles  triangle, 
bear  the  same  relation  to  the  globe  of  the  eye,  and  are  inserted  in 
a  similar  manner  into  the  sclerotica,  at  about  two  lines  from  the 
circumference  of  the  cornea.      The  points  of  difference  relate  to 
thickness  and  length ;  the  internal  rectus  is  the  thickest  and  most 
short,  the  external  rectus  the  longest  of  the  four,  and  the  superior 
rectus  the  most  thin.     The  insertion  of  the  four  recti  muscles  into 
the  globe  of  the  eye  forms  a  tendinous  expansion,  which  is  continued 
as  far  as  the  margin  of  the  cornea,  and  is  called  the  tunica  albuginea. 
The  obliquus  superior  (trochlearis)  is  a  fusiform  muscle  arising 
from  the  margin  of  the  optic  foramen,  and  from  the  fibrous  sheath 
of  the  optic  nerve ;  it  passes  forwards  to  the  pulley  beneath  the 
internal  angular  process  of  the  frontal  bone ;    its  tendon  is  then 
reflected  beneath  the  superior  rectus  muscle,  to  the  outer  and  poste- 
rior part  of  the  globe  of  the  eye,  where    it  is  inserted  into  the 
sclerotic  coat,  near  the  entrance  of  the  optic  nerve.     The  tendon  is 
surrounded  by  a  synovial  membrane,  while  passing  through  the 
cartilaginous  pulley. 

Relations. — By  its  superior  surface  with  the  fourth  nerve,  the 
supra-trochlear  nerve,  and  with  the  periosteum  of  the  orbit.  By  the 
inferior  surface  with  the   adipose   tissue  of  the  orbit,  the    upper 


150  OCULAR  GROUP. 

border  of  the  internal  rectus,  and  the  vessels  and  nerves  in  rela- 
tion with  that  border. 

The  obliquus  inferior,  a  thin  and  narrow  muscle,  arises  from  the 
inner  margin  of  the  superior  maxillary  bone,  immediately  external 
to  the  lachrymal  groove,  and  passes  beneath  the  inferior  rectus,  to 
be  inserted  into  the  outer  and  posterior  part  of  the  eyeball,  at  about 
two  lines  from  the  entrance  of  the  optic  nerve. 

Relations. — By  its  superior  surface  with  the  inferior  rectus  muscle 
and  with  the  eyeball ;  and  by  the  inferior  surface  with  the  perios- 
teum of  the  floor  of  the  orbit  and  the  external  rectus  muscle. 

According  to  Mr.  Ferrall*  the  muscles  of  the  orbit  are  separated 
from  the  globe  of  the  eyeball  and  from  the  structures  immediately 
surrounding  the  optic  nerve,  by  a  distinct  fascia,  which  is  continuous 
with  the  broad  tarsal  ligament  and  with  the  tarsal  cartilages.  This 
fascia  the  author  terms,  the  tunica  vaginalis  oculi;\  it  is  pierced 
anteriorly  for  the  passage  of  the  six  orbital  muscles,  by  six  openings 
through  which  the  tendons  of  the  muscles  play  as  tlirough  pulleys. 
The  use  assigned  to  it  by  Mr.  Ferrall  is  to  protect  the  eyeball  from 
the  pressure  of  its  muscles  during  their  action.  By  means  of  this 
structure  the  recti  muscles  are  enabled  to  impress  a  rotatory  move- 
ment upon  the  eyeball ;  and  in  animals  provided  with  a  retractor 
muscle,  they  also  act  as  antagonists  to  its  action. 

Actions. — The  levator  palpebrse  raises  the  upper  eyelid.  The  four 
recti,  acting  singly,  pull  the  eyeball  in  the  four  directions  of  upwards, 
downwards,  inwards,  and  outwards.  Acting  by  pairs,  they  carry 
the  eyeball  in  the  diagonal  of  these  directions,  viz.  upwards  and 
inwards,  upwards  and  outwards,  downwards  and  inwards,  or 
downwards  and  outwards.  Acting  altogether,  they  directly  retract 
the  globe  within  the  orbit.  The  superior  oblique  muscle,  acting 
alone,  rolls  the  globe  inv/ards  and  forwards,  and  carries  the  pupil 
outwards  and  downwards  to  the  lower  and  outer  angle  of  the  orbit. 
The  inferior  oblique,  acting  alone,  rolls  the  globe  outwards  and 
backwards,  and  carries  the  pupil  outwards  and  upwards  to  the 
upper  and  outer  angle  of  the  eye.  Both  muscles  acting  together, 
draw  the  eyeball  forwards,  and  give  the  pupil  that  slight  degree  of 
aversion  which  enables  it  to  admit  the  largest  field  of  vision. 


&^ 


4.  JVasal  Group. — -Pyramidalis  nasi,J 
Compressor  nasi. 

The  pyramidalis  nasi  is  a  small  pyramidal  slip  of  muscular  fibres 
sent  downwards  upon  the  nose  by  the  occipito-frontalis.  It  is 
inserted  into  the  tendinous  expansion  of  the  compressores  nasi. 

Relations. — By  its  upper  surface  with  the  integument;  by  its 
under  surface  with  the  periosteum  of  the  nasal  bone.     Its  outer 

*  In  a  paper  read  before  the  Royal  Society,  on  the  10th  of  June,  1841, 
t  This  faso-ia  was  first  described  by  Mr.  Dalrymple  in  his  work  on  the  "Anatomy 
of  the  Human  Eye."  1834. 

t  This  is  described  by  Horner  as  one  of  the  insertions  of  the  occipito-frontalis.  G. 


SUPERIOR  LABIAL  GROUP.  151 

border  corresponds  with  the  edge  of  the  orbicularis  palpebrarum, 
and  its  inner  border  with  its  fellow,  from  which  it  is  separated  by 
a  slight  interval. 

The  compressor  nasi  is  a  thin  and  triangular  muscle;  it  arises  by- 
its  apex  from  the  canine  fossa  of  the  superior  maxillary  bone,  and 
spreads  out  upon  the  side  of  the  nose  into  a  thin  tendinous  expan- 
sion, which  is  continuous  across  its  ridge  with  the  muscle  of  the 
opposite  side. 

Relations. — By  its  superficial  surface  with  the  levator  labii  supe- 
rioris  proprius,  the  levator  labii  superioris  aleeque  nasi,  and  the  inte- 
gument ;  by  its  deep  surface  with  the  superior  maxillary  and  nasal 
bone,  and  with  the  alar  and  lateral  cartilages  of  the  nose. 

Actions. — The  pyramidalis  nasi,  as  a  point  of  attachment  of  the 
occipito-frontalis,  assists  that  muscle  in  its  action:  it  also  draws 
down  the  inner  angle  of  the  eyebrow,  and  by  its  insertion  fixes  the 
aponeurosis  of  the  compressores  nasi.  The  compressores  nasi 
appear  to  act  in  expanding  rather  than  in  compressing  the  nares ; 
hence  probably  the  compressed  state  of  the  nares  from  paralysis  of 
these  muscles  in  the  last  moments  of  life,  or  in  compression  of  the 
brain. 

5.  Superior  Labial  Group. — Orbicularis  oris. 

Levator  labii  superioris  alseque  nasi, 
Levator  labii  superioris  proprius,* 
Levator  anguli  oris, 
Zygomaticus  major, 
Zygomaticus  minor, 
Depressor  labii  superioris  alsequenasi. 

The  orbicularis  oris  is  a  sphincter  muscle,  completely  surrounding 
the  mouth,  and  possessing  consequently  neither  origin  nor  insertion. 
It  is  composed  of  two  thick  semicircular  planes  of  fibres,  which  em- 
brace the  rima  of  the  mouth,  and  interlace  at  their  extremities, 
where  they  are  continuous  with  the  fibres  of  the  buccinator,  and  of 
the  other  muscles  connected  with  the  angle  of  the  mouth.  The 
upper  segment  is  attached  by  means  of  a  small  muscular  fasciculus 
(naso-labiahs)  to  the  columna  of  the  nose. 

Relations. — By  its  superficial  surface  with  the  integument  of  the 
lips  with  which  it  is  closely  connected.  By  its  deep  surface  with 
the  mucous  membrane  of  the  mouth,  the  labial  glands  and  coronary 
arteries  being  interposed.  By  its  circumference  with  the  numerous 
muscles  which  move  the  lips,  and  by  the  inner  border  with  the 
mucous  membrane  of  the  rima  of  the  mouth. 

The  levator  labii  superioris  alceque  nasi  is  a  thin  triangular  muscle; 
it  arises  from  the  nasal  process  of  the  superior  maxillary  bone;  and, 
becoming  broader  as  it  descends,  is  inserted  by  two  distinct  por- 
tions into  the  integument  of  the  ala  of  the  nose  and  upper  lip. 

Relations. — By  its  superficial  surface  with  a  part  of  the  orbicularis 

*  These  two  levators  are  described  as  one  by  Horner. — G. 


152  SUPERIOR  LABIAL  GROUP. 

palpebrarum  muscle,  the  facial  artery,  and  the  integument.  By  its 
deep  surface  with  the  compressor  nasi  and  alar  cartilage. 

The  levator  lahii  swperioris  proprius  is  a  thin  quadrilateral  muscle; 
it  nrises  from  the  lower  border  of  the  orbit,  and  is  inserted  into  the 
integument  of  the  upper  lip. 

Relations. — By  its  superficial  surface  with  the  lower  segment  of 
the  orbicularis  palpebrarum,  with  the  facial  artery,  and  Avith  the 
integument.  By  its  deep  surface  with  the  origins  of  the  compressor 
nasi  and  levator  anguli  oris  muscle,  and  with  the  infra-orbital  artery 
and  nerve. 

The  levator  anguli  oris  arises  from  the  canine  fossa  of  the  supe- 
rior maxillary  bone,  and  passes  outwards  to  be  inserted  into  the 
angle  of  the  mouth,  intermingling  its  fibres  with  those  of  the  orbicu- 
laris, zygomatici  and  depressor  anguli  oris. 

Relations. — By  its  superficial  surface  with  the  levator  labii  supe- 
rioris  proprius,  the  branches  of  the  infra-orbital  artery  and  nerve, 
and  inferiorly  with  the  integument.  By  its  deep  surface  with  the 
superior  maxillary  bone  and  buccinator  muscle. 

The  zygomatic  muscles  are  two  slender  fasciculi  of  fibres  which 
arise  from  the  malar  bone,  and  are  inserted  into  the  angle  of  the 
mouth,  where  they  are  continuous  with  the  other  muscles  attached 
to  this  part.  The  zygomaticus  minor  is  situated  in  front  of  the 
major,  and  is  continuous  at  its  insertion  with  the  levator  labii  supe- 
rioris  proprius  ;  it  is  not  unfrequently  wanting. 

Relations. — The  zygomaticus  tnajor  muscle  is  in  relation  by  its 
superficial  surface  with  the  lower  segment  of  the  orbicularis  palpe- 
brarum above,  and  the  fat  of  the  cheek  and  integument  for  the  rest 
of  its  extent.  By  its  deep  surface  with  the  malar  bone,  the  masseter, 
and  buccinator  muscle,  and  the  facial  vessels.  The  zygomaticus 
minor  being  in  front  of  the  major,  has  no  relation  with  the  masseter 
muscle,  while  inferiorly  it  rests  upon  the  levator  anguli  oris. 

The  depressor  labii  superioris  alaeque  nasi  (myrtiformis)  is  seen 
by  drawing  upwards  the  upper  lip,  and  raising  the  mucous  mem- 
brane. It  is  a  small  oval  slip  of  muscle,  situated  at  each  side  of  the 
frsenum,  arising  from  the  incisive  fossa,  and  passing  upwards  to  be 
inserted  into  the  upper  lip  and  ala  of  the  nose.  This  muscle  is  con- 
tinuous by  its  outer  border  with  the  edge  of  the  compressor  nasi. 

Relations. — By  its  superficial  surface  with  the  mucous  membrane 
of  the  mouth,  the  orbicularis  oris  and  levator  labii  superioris  alaeque 
nasi  muscle ;  and  by  its  deep  surface  with  the  superior  maxillary 
bone. 

Actions. — The  orbicularis  oris  produces  the  direct  closure  of  the 
lips  by  means  of  its  continuity  at  the  angles  of  the  mouth,  with  the 
fibres  of  the  buccinator.  When  acting  singly  in  the  forcible  closure 
of  the  mouth,  the  integument  is  thrown  into  wrinkles  in  consequence 
of  its  firm  connexion  with  the  surface  of  the  muscle.  The  levator 
labii  superioris  alseque  nasi  lifts  the  upper  lip  with  the  ala  of  the  nose, 
and  expands  the  opening  of  the  nares.  The  depressor  labii  superioris 
ala?que  nasi  is  the  antagonist  to  this  muscle,  drawing  the  upper  lip 


INFERIOR  LABIAL  GROUP.  153 

and  ala  of  the  nose  downwards,  and  diminishing  the  opening  of  the 
nares.  The  levator  labii  superioris  proprius  is  the  proper  elevator 
of  the  upper  Up ;  acting  singly,  it  draws  the  lip  a  little  to  one  side. 
The  levator  anguli  oris  lifts  the  angle  of  the  mouth  and  draws  it 
inwards,  while  the  zygomatici  pull  it  upwards  and  outwards,  as  in 
laughing. 

6.  hiferior  Labial  Group. — Depressor  labii  inferioris. 

Depressor  anguli  oris, 
Levator  labii  inferioris. 

Dissection. — To  dissect  the  inferior  labial  region,  continue  the  ver- 
tical section  from  the  margin  of  the  lower  lip  to  the  point  of  the 
chin.  Then  carry  an  incision  along  the  margin  of  the  lower  jaw  to 
its  angle.  Dissect  off  the  integument  and  superficial  fascia  from  the 
whole  of  this  surface,  and  the  muscles  of  the  inferior  labial  region 
will  be  exposed. 

The  depressor  labii  inferioris  (quadratus  menti)  arises  from  the 
oblique  line  by  the  side  of  the  symphysis  of  the  lower  jaw,  and  pass- 
ing upwards  and  inwards  \s  inserted  into  the  orbicularis  muscle  and 
integument  of  the  lower  lip. 

Relations. — By  its  superficial  surface  with  a  part  of  the  depressor 
anguli  oris,  and  with  the  integument  of  the  chin  with  which  it  is 
closely  connected.  By  the  deep  surface  with  the  levator  labii  in- 
ferioris, the  labial  glands  and  mucous  membrane  of  the  lower  lip, 
and  with  the  mental  nerve  and  artery. 

The  depressor  anguli  oris  (triangularis  oris)  is  a  triangular  plane  of 
muscle  arising  by  a  broad  base  from  the  external  oblique  ridge  of  the 
lower  jaw,  and  inserted  by  its  apex  into  the  angle  of  the  mouth,  where 
it  is  continuous  with  the  levator  anguli  oris  and  zygomaticus  major. 

Relations. — By  its  superficial  surface  with  the  integument,  and  by 
its  deep  surface  with  the  depressor  labii  inferioris,  the  platysma  my- 
oides,  the  buccinator  and  the  branches  of  the  mental  nerve  and  artery. 

The  levator  labii  inferioris  (levator  menti)  is  a  small  conical  slip 
of  muscle  arising  from  the  incisive  fossa  of  the  lower  jaw,  and 
inserted  into  the  integument  of  the  chin.  It  is  in  relation  with  the 
mucous  membrane  of  the  mouth,  with  its  fellow,  and  with  the 
depressor  labii  inferioris. 

Jlciions. — The  depressor  labii  inferioris  draws  the  lower  lip  di- 
rectly downwards,  and  at  the  same  time  a  little  outwards.  The 
depressor  anguli  oris,  from  the  radiate  direction  of  its  fibres,  will  pull 
the  angle  of  the  mouth  either  downwards  and  inwards,  or  down- 
wards and  outwards,  and  be  expressive  of  grief;  or  acting  with  the 
levator  anguli  oris  and  zygomaticus  major,  it  will  draw  the  angle 
of  the  mouth  directly  backwards.  The  levator  labii  inferioris  raises 
and  protrudes  the  integument  of  the  chin. 

7.  Maxillary  Group. — Masseter, 

TemporaUs, 
Buccinator, 
Pterygoideus  externus, 
Pterygoideus  internus. 
20 


154  MAXILLARY  GROUr. 

Dissection. — The  masseter  has  been  ah'eady  exposed  by  the  pre- 
ceding dissection. 

The  masseter  ((ji^atfCaofxai,  to  chew,)  is  a  short  and  thick  and  some- 
what quadrilateral  muscle,  composed  of  two  planes  of  fibres,  super- 
ficial and  deep.  The  superficial  layer  aiises  by  a  strong  aponeuro- 
sis from  the  tuberosity  of  the  superior  maxillary  bone,  and  from  the 
lower  border  of  the  malar  bone  and  zygoma,  and  passes  backwards 
to  be  inserted  into  the  ramus  and  angle  of  the  inferior  maxilla.  The 
deep  layer  arises  from  the  posterior  part  of  the  zygoma,  and  passes 
forwards,  to  be  inserted  into  the  upper  half  of  the  ramus.  This 
muscle  is  tendinous  and  muscular  in  its  structure. 

Relations. — By  its  external  surface  with  the  zygomaticus  major 
and  risorius  Santorini  muscle,  the  parotid  gland  and  Stenon's  duct, 
the  transverse  facial  artery,  the  pes  anserinus  and  the  integument. 
By  its  internal  surface  with  the  temporal  muscle,  the  buccinator, 
from  which  it  is  separated  by  a  large  mass  of  fat,  and  with  the 
ramus  of  the  lower  jaw.  By  its  posterior  harder  with  the  parotid 
gland ;  and  by  the  anterior  border  with  the  facial  artery  and  vein. 

Dissection. — Make  an  incision  along  the  upper  border  of  the 
zygoma,  for  the  purpose  of  separating  the  temporal  fascia  from  its 
attachment.  Then  saw  through  the  zygomatic  process  of  the  malar 
bone,  and  through  the  root  of  the  zygoma,  near  to  the  meatus  audi- 
torius.  Draw  down  the  zygoma,  and  with  it  the  origin  of  the  mas- 
seter, and  dissect  the  latter  muscle  away  from  the  ramus  and  angle 
of  the  inferior  maxilla.  Now  remove  the  temporal  fascia  from  the 
rest  of  its  attachment,  and  the  whole  of  the  temporal  muscle  will  be 
exposed. 

The  temporal  is  a  broad  and  radiating  muscle  occupying  a  consi- 
derable extent  of  the  side  of  the  head  and  filling  the  temporal  fossa. 
It  is  covered  in  by  a  very  dense  fascia  (temporal  fascia)  which  is 
attached  along  the  temporal  ridge  on  the  side  of  the  skull,  extending 
from  the  external  angular  process  of  the  frontal  bone  to  the  mastoid 
portion  of  the  temporal ;  inferiorly,  it  is  connected  to  the  upper 
border  of  the  zygoma.  The  muscle  arises  by  tendinous  fibres  from 
the  whole  length  of  the  temporal  ridge  and  by  muscular  fibres  from 
the  temporal  fascia,  and  from  the  entire  surface  of  the  temporal 
fossa.  Its  fibres  converge  to  a  strong  and  narrow  tendon,  which  is 
inserted  into  the  apex  of  the  coronoid  process,  and  for  some  way 
down  upon  its  inner  surface. 

Relations. — By  its  external  surface  with  the  temporal  fascia, 
which  separates  it  from  the  attollens  and  attrahcns  aurem  muscle, 
the  temporal  vessels  and  nerves ;  and  with  the  zygoma  and  masseter. 
By  its  internal  surface  with  the  bones  forming  the  temporal  fossa, 
the  external  pterygoid  muscle,  a  part  of  the  buccinator,  and  the  in- 
ternal maxillary  artery,  with  its  deep  temporal  branches. 

By  sawing  through  the  coronoid  process  near  to  its  base,  and  pull- 
ing it  upwards,  together  with  the  tein])oral  muscle,  which  may  be 
dissected  from  the  fossa,  we  obtain  a  view  of  the  entire  extent  of  the 
buccinator  and  of  the  external  pterygoid  muscle. 


BUCCINATOR PTERYGOIDEI.  155 

The  buccinator  {huccina,  a  trumpet),  the  trumpeter's  muscle, 
arises  from  the  alveolar  process  of  the  superior  maxillary  and  from 
the  external  oblique  line  of  the  inferior  maxillary  bone,  as  far  for- 
ward as  the  second  bicuspid  tooth,  and  from  the  pterygo-m axillary 
ligament.  This  ligament  is  the  raphe  of  union  between  the  bucci- 
nator and  superior  constrictor  muscle,  and  is  attached  by  one  extre- 
mity to  the  hamular  process  of  the  internal  pterygoid  plate,  and  by 
the  other  to  the  extremity  of  the  molar  ridge.  The  fibres  of  the 
muscle  converge  towards  the  angle  of  the  mouth  where  they  cross 
each  other,  the  superior  being  continuous  with  the  inferior  segment 
of  the  orbicularis  oris,  and  the  inferior  with  the  superior  segment. 
The  muscle  is  invested  externally  by  a  thin  fascia. 

Relations. — By  its  external  surface,  posteriorly  with  a  large  and 
rounded  mass  of  fat,  which  separates  the  muscle  from  the  ramus  of 
the  lower  jaw,  the  temporal,  and  the  masseter ;  anteriorly  with  the 
risorius  Santorini,  the  zygomatici,  the  levator  anguli  oris,  and  the 
depressor  anguh  oris.  It  is  also  in  relation  with  a  part  of  Stenon's 
duct  which  pierces  it  opposite  to  the  second  molar  tooth  of  the 
upper  jaw,  with  the  transverse  facial  artery,  the  branches  of  the 
facial  and  buccal  nerve,  and  the  facial  artery  and  vein.  By  its 
internal  surface  with  the  buccal  glands  and  mucous  membrane 
of  the  mouth. 

The  external  pterygoid  is  a  short  and  thick  muscle,  broader  at 
its  origin  than  at  its  insertion.  It  arises  by  two  heads,  one  from 
the  pterygoidr  idge  on  the  great  ala  of  the  sphenoid  ;  the  other  from 
the  external  pterygoid  plate  and  tuberosity  of  the  palate  bone.  The 
fibres  pass  backwards  to  be  inserted  into  the  neck  of  the  lower  jaw 
and  the  interarticular  fibro-cartilage.  The  internal  maxillary  artery 
frequently  passes  between  the  two  heads  of  this  muscle. 

Relations. — By  its  external  surface  with  the  ramus  of  the  lower 
jaw,  the  temporal  muscle,  and  the  internal  maxillary  artery ;  by  its 
internal    surface     with    the    internal 
pterygoid    muscle,    and    the    inferior  Fig.  70.* 

maxillary  nerve ;  and  by  its  upper 
border  with  the  muscular  branches  of 
the  inferior  maxillary  nerve ;  the  in- 
ternal maxillary  artery  passes  between 
the  two  heads  of  this  muscle,  and  its 
lower  origin  is  pierced  by  the  buccal 
nerve. 

The  external  pterygoid  muscle  must 
now  be  removed,  the  ramus  of  the 
lower  jaw  sawn  through  its  lower 
third,  and  the  head  of  the  bone  dislo- 
cated from  its  socket  and  withdrawn,  for  the  purpose  of  seeing  the 
pterygoideus  internus. 

*  The  two  pterygoid  muscles.  The  zygomatic  arch  and  greater  part  of  tlie  ramus 
of  the  lower  jaw  have  been  removed  in  order  to  bring  these  muscles  into  view.  1.  Tlic 
sphenoid  origin  of  the  external  pterygoid  muscle.  2.  Its  pterygoid  origin.  3.  The 
internal  pterygoid  muscle. 


156  AURICULAE  GROUP, 

The  inlerjial  pterygoid  is  a  thick  quadrangular  muscle.  It  arises 
from  the  pterygoid  fossa,  and  descends  obliquely  backwards,  to  be 
inserted  into  the  ramus  and  angle  of  the  lower  jaw  :  it  resembles 
the  masseter  in  appearance  and  direction,  and  was  named  by 
Winslow  the  internal  masseter. 

Relations. — By  its  external  surface  with  the  internal  pterygoid, 
the  inferior  maxillary  nerve  and  its  branches,  the  internal  maxillary 
artery  and  branches,  the  internal  lateral  ligament,  and  the  ramus  of 
the  lower  jaw.  By  its  internal  surface  with  the  tensor  palati  and 
superior  constrictor  of  the  pharynx  with  its  fascia ;  and  by  its  pos- 
terior border  with  the  parotid  gland. 

Actions. — The  maxillary  muscles  are  the  active  agents  in  masti- 
cation, and  form  an  apparatus  beautifully  fitted  for  that  office.  The 
buccinator  circumscribes  the  cavity  of  the  mouth,  and  with  the  aid 
of  the  tongue  keeps  the  food  under  the  immediate  pressure  of  the 
teeth.  By  means  of  its  connexion  with  the  superior  constrictor,  it 
shortens  the  cavity  of  the  pharynx,  from  before  backwards,  and 
becomes  an  important  auxiliary  in  deglutition.  The  temporal,  the 
masseter,  and  the  internal  pterygoid  are  the  bruising  muscles,  draw- 
ing the  lower  jaw  against  the  upper  with  great  force.  The  two 
latter,  by  the  obliquity  of  their  direction,  assist  the  external  ptery- 
goid in  grinding  the  food  by  carrying  the  lower  jaw  forward  upon 
the  upper ;  the  jaw  being  brought  back  again  by  the  deep  portion 
of  the  masseter  and  posterior  fibres  of  the  temporal.  The  whole  of 
these  muscles,  acting  in  succession,  produce  a  rotatory  movement 
of  the  teeth  upon  each  other,  which,  with  the  direct  action  of  the 
lower  jaw  against  the  upper,  effects  the  proper  mastication  of  the 
food. 

8.  Auricular  Group. — Attollens  aurem, 
Attrahens  aurem, 
Retrahens  aurem. 

Dissection. — The  three  small  muscles  of  the  ear  may  be  exposed 
by  removing  a  square  of  integument  from  around  the  auricula. 
This  operation  must  be  performed  with  care,  otherwise  the  muscles, 
which  are  extremely  thin,  will  be  raised  with  the  superficial  fascia. 

The  attollens  aurem  (superior  auris),  the  largest  of  the  three,  is  a 
thin  triangular  plane  of  muscular  fibres  arising  from  the  edge  of  the 
aponeurosis  of  the  occipito-frontalis,  and  inserted  into  the  upper 
part  of  the  concha. 

It  is  in  relation  by  its  external  surface  with  the  integument,  and 
by  the  internal  with  the  temporal  aponeurosis. 

The  attrahens  aurem  (anterior  auris,)  also  triangular,  arises  from 
the  edge  of  the  aponeurosis  of  the  occipito-frontalis  ;  and  is  inserted 
into  the  anterior  part  of  the  concha,  covering  in  the  anterior  and 
posterior  temyjoral  arteries. 

It  is  in  relation  by  its  external  surface  with  the  integument;  and 
by  the  internal  with  the  temporal  aponeurosis  and  with  tiie  temporal 
artery  and  veins. 


MUSCLES  OF  THE  NECK. 


157 


The  retrahens  aurem  (posterior  auris,)  arises  by  three  or  four 
muscular  shps  from  the  mastoid  process.  They  are  inserted  into 
the  posterior  surface  of  the  concha. 

It  is  in  relation  by  its  external  surface  with  the  integument,  and 
by  its  internal  surface  with  the  mastoid  portion  of  the  temporal  bone. 

Actions. — The  muscles  of  the  auricular  region  possess  but  little 
action  in  man ;  they  are  ■  the  analogues  of  important  muscles  in 
brutes.     Their  use  is  sufficiently  explained  by  their  names. 

Muscles  of  the  JVeck. — The  muscles  of  the  neck  may  be  arranged 
into  eight  groups  corresponding  with  the  natural  divisions  of  the 
region;  they  are  the — 

1.  Superficial  group. 

2.  Depressors  of  the  os  hyoides  and  larynx. 

3.  Elevators  of  the  os  hyoides  and  larynx. 

4.  Lingual  group. 

5.  Pharyngeal  group. 

6.  Soft  palate  group. 

7.  Prevertebral  group. 

8.  Proper  muscles  of  the  larynx. 

And  each  of  these  groups  consists  of  the  following  muscles : — viz. 
1.  Superficial  Group. 


Platysma  myoides, 
Sterno-cleido-mastoideus. 

2.  Depressors  of  the  os 
hyoides  and  larynx. 

Sterno-hyoideus, 
Sterno-thyroideus, 
Thyro-hyoideus, 
Omo-hyoideus. 

3.  Elevators  of  the  os 
hyoides  and  larynx. 

Digastricus, 

Stylo-hyoideus, 

Mylo-hyoideus, 

Genio-hyoideus, 

Genio-hyo-glossus. 

4.  Muscles  of  the  tongue. 

Genio-hyo-glossus, 

Hyo-glossus, 
Lingualis, 
Stylo-glossus, 
Palato-glossus.* 


5.  Muscles  of  the  Pharynx. 
Constrictor  inferior, 
Constrictor  medius, 
Constrictor  superior, 
Stylo-pharyngeus, 
Palato-pharyngeus. 

6.  Muscles  of  the  soft  Palate. 
Levator  palati, 

Tensor  palati, 
Azygos  uvulae, 
Palato-glossus,* 
Palato-pharyngeus, 

7.  Prcxvertehral  Group. 
Rectus  anticus  major. 
Rectus  anticus  minor, 
Scalenus  anticus. 
Scalenus  posticus, 
Longus  colli. 

8.  Muscles  of  the  Larynx. 
Crico-thyroideus, 
Crico-aryttenoideus,  posticus, 
Crico-aryt£enoideus,  lateralis, 
Thyro-arytasnoideus, 
Aryteenoideus. 


Described  by  Horner  as  the  Constrictor  isthmii  faucium. — G. 


158  STERNO-CLEIDO-MASTOIDEUS. 

Dissection. — The  dissection  of  the  neck  should  be  commenced  by 
making  an  incision  along  the  middle  line  of  the  neck  from  the  chin 
to  the  sternum,  and  bounding  it  superiorly  and  inferiorly  by  two 
transverse  incisions ;  the  superior  one  being  carried  along  the 
margin  of  the  lower  jaw,  and  across  the  mastoid  process  to  the 
tubercle  on  the  occipital  bone,  the  inferior  one  along  the  clavicle  to 
the  acromion  process.  The  square  flap  of  integument  thus  included 
should  be  turned  back  from  the  entire  side  of  the  neck,  which  brings 
into  view  the  superficial  fascia,  and  on  the  removal  of  a  thin 
layer  of  superficial  fascia  the  platysma  myoides  will  be  exposed. 

The  platysma  myoides  ("rrXarvs,  (xuj,  slSog,  broad  muscle-like  lamella,) 
is  a  thin  plane  of  muscular  fibres,  situated  between  the  two  layers 
of  the  superficial  cervical  fascia ;  it  arises  from  the  integument  over 
the  pectoralis  major  and  deltoid  muscles,  and  passes  obliquely  up- 
wards and  inwards  along  the  side  of  the  neck  to  be  inserted  into 
the  side  of  the  chin,  oblique  line  of  the  lower  jaw,  the  angle  of  the 
mouth,  and  into  the  cellular  tissue  of  the  face.  The  most  anterior 
fibres  are  continuous  beneath  the  chin,  with  the  muscle  of  the  op- 
posite side ;  the  next  interlace  with  the  depressor  anguh  oris,  and 
depressor  labii  inferioris,  and  the  most  posterior  fibres  are  disposed 
in  a  transverse  direction  across  the  side  of  the  face,  arising  in  the 
cellular  tissue  covering  the  parotid  gland,  and  inserted  into  the 
angle  of  the  mouth,  constituting  the  risorius  Santorini.  The  entire 
muscle  is  analogous  to  the  cutaneous  muscle  of  brutes,  the  pannicu- 
lus  carnosus. 

Relations. — By  its  external  surface  with  the  integument,  with 
which  it  is  closely  adherent  below,  but  loosely  above.  By  its  internal 
surface,  below  the  clavicle,  with  the  pectoralis  major  and  deltoid  ; 
in  the  neck,  with  the  external  jugular  vein  and  deep  cervical  fascia  ; 
on  the  face,  with  the  parotid  gland,  the  masseter,  the  facial  artery 
and  vein,  the  buccinator,  the  depressor  anguli  oris,  and  the  depres- 
sor labii  inferioris. 

On  raising  the  platysma  throughout  its  whole  extent,  the  sterno- 
mastoid  is  brought  into  view. 

The  sterno-cleido  mastoid  is  the  largest  oblique  muscle  of  the 
■neck,  and  is  situated  between  two  layers  of  the  deep  cervical  fascia. 
It  arises  as  implied  in  its  name  from  the  sternum  and  clavicle 
(3cXsi(5iov),  and  passes  obliquely  upwards  and  backwards  to  be  inserted 
into  the  mastoid  process  and  into  the  superior  curved  line  of  the 
occipital  bone.  The  sternal  portion  arises  by  a  rounded  tendon, 
increases  in  breadth  as  it  ascends,  and  spreads  out  to  a  considerable 
extent  at  its  insertion.  The  clavicular  portion  is  broad  and  fleshy, 
and  separate  from  the  sternal  portion  below,  but  becomes  gradually 
blended  with  its  posterior  surface  as  it  ascends. 

Relations. — By  its  superficial  surface  with  the  integument,  the 
platysma  myoides,  the  external  jugular  vein,  superficial  branches  of 
the  anterior  cervical  plexus  of  nerves,  and  the  anterior  layer  of  the 
deep  cervical  fascia.  By  its  deep  surface  with  the  deep  layer  of 
the  cervical  fascia ;  with  the  sterno-clavicular  articulation,  the 
sterno-hyoid,    stcrno-thyroid,   omo-hyoid,   scaleni,   levator    anguli 


STEKNO-CLEIDO-MASTOIDEUS. 


159 


scapulae,  splenii,  and  posterior  belly  of  the  digastric  muscle ;  with 
the  phrenic  nerve,  and  the  posterior,  and  supra-scapular  artery ;  with 
the  deep  lymphatic  glands,  the  sheath  of  the  common  carotid  arteiy 
and  internal  jugular  vein,  the  descendens  noni  nerve,  the  external 
carotid  artery  and  its  posterior  branches,  the  commencement  of  the 
internal  carotid  artery ;  with  the  cervical  plexus  of  nerves,  the 
pneumogastric,  the  spinal  accessory,  the  hypoglossal,  the  sympa- 
thetic and  the  facial  nerve,  and  with  the  parotid  gland.  It  is 
pierced  on  this  aspect  by  the  spinal  accessory  nerve  and  by  the 

Fig.  71  * 


branches  of  the  mastoid  artery.  The  anterior  border  of  the  muscle 
is  the  posterior  boundary  of  the  great  anterior  triangle,  the  other 
two  boundaries  being  the  middle  line  of  the  neck  in  front,  and  the 
lower  border  of  the  jaw  above.  It  is  the  guide  to  the  operations 
for  the  ligature  of  the  common  carotid  artery  and  arteria  innomi- 
nata,  and  for  ojsophagotomy.  The  posterior  border  is  the  anterior 
boundary  of  the  great  posterior  triangle ;  the  other  two  boundaries 
being  the  anterior  border  of  the  trapezius  behind,  and  the  clavicle 
below. 

Actions. — The  platysma  produces  a  muscular  traction  on  the 
integument  of  the  neck,  which  prevents  it  from  falling  so  flaccid  in 

*  The  muscles  of  the  anterior  aspect  of  the  neck ;  on  the  left  side  the  superficial 
muscles  are  seen,  and  on  the  right  the  deep.  1.  The  posterior  belly  of  the  digastricus 
muscle.  2.  Its  anterior  belly.  The  aponeurotic  pulley,  through  which  its  tendon  is 
seen  passing,  is  attached  to  the  body  of  the  os  hyoides  3.  4.  The  stylo-hyoidcus  mus- 
cle, transfixed  by  the  posterior  belly  of  the  digastricus.  5,  The  mylo-liyoideus.  6. 
The  genio-hyoideus.  7.  The  tongue.  8.  The  hyo-glossus.  9.  The  stylo-glossus. 
10.  The  stylo-pharyngeus.  11.  The  sterno-mastoid  muscle.  12.  Its  sternal  origin. 
13.  Its  clavicular  origin,  14.  The  sterno-hyoid.  15.  The  stcrno-thyroid  of  the  right 
side.  16.  The  thyro-hyoid.  17.  The  hyoid  portion  of  the  omo-hyoid.  18,  18.  Its 
scapular  portion  ;  on  the  left  side,  the  tendon  of  the  muscle  is  seen  to  be  bound  down 
by  a  portion  of  the  deep  cervical  fascia.  19.  The  clavicular  portion  of  the  trapezius. 
20.  The  scalenus  anticus,  of  the  right  side.     21.  The  scalenus  posticus. 


160  DEPRESSORS  OF  THE  OS  HYOIDES  AND  LAKYMX. 

old  persons  as  would  be  the  case  if  the  extension  of  the  skin  were 
the  mere  result  of  elasticity.  It  draws  also  upon  the  angle  of  the 
mouth,  and  is  one  of  the  depressors  of  the  lower  jaw.  The  trans- 
verse fibres  draw  the  angle  of  the  mouth  outwards  and  slightly 
upwards'.  The  sterno-mastoid  muscles  are  the  great  anterior  mus- 
cles of  connexion  between  the  thorax  and  the  head.  Both  mus- 
cles acting  together  will  bow  the  head  directly  forwards,  The 
clavicular  portions,  acting  more  forcibly  than  the  sternal,  give 
stability  and  steadiness  to  the  head  in  supporting  great  weights. 
Either  muscle  acting  single  would  draw  the  head  towards  the 
shoulder  of  the  same  side,  and  carry  the  face  towards  the  opposite 
side. 

Second  Group. — Depressors  of  the  Os  Hyoides  and  Larynx. 
Sterno-hyoid, 
Sterno-thyroid, 
Thyro-hyoid, 
Omo-hyoid. 

Dissection. — These  muscles  are  brought  into  view  by  removing 
the  deep  fascia  from  off  the  front  of  the  neck  between  the  two 
sterno-mastoid  muscles.  The  omo-hyoid  to  be  seen  in  its  whole 
extent  requires  that  the  sterno-mastoid  muscle  be  divided  from  its 
origin  and  turned  aside. 

The  sterno-hyoideus  is  a  narrow  riband-like  muscle,  arising  from 
the  posterior  surface  of  the  jRrst  bone  of  the  sternum  and  inner  ex- 
tremity of  the  clavicle.  It  is  inserted  into  the  lower  border  of  the 
body  of  the  os  hyoides.  The  sterno-hyoidei  are  separated  by  a  con- 
siderable interval  at  the  root  of  the  neck,  but  approach  each  other 
as  they  ascend ;  they  are  frequently  traversed  by  a  tendinous  inter- 
section. 

Relations. — By  its  external  surface  with  the  deep  cervical  fascia, 
the  platysma  myoides  and  sterno-mastoid  muscle;  by  its  internal 
surface  with  the  sterno-thyroid  and  thyro-hyoid  muscle,  the  thyroid 
gland,  and  the  superior  thyroid  artery. 

The  sterno-thyroideus,  broader  than  the  preceding  beneath  which 
it  lies,  arises  from  the  posterior  surface  of  the  upper  bone  of  the 
sternum,  and  from  the  cartilage  of  the  first  rib ;  and  is  inserted  into 
the  oblique  line,  on  the  great  ala  of  the  thyroid  cartilage.  The  inner 
borders  of  these  muscles  lie  in  contact  along  the  middle  line,  and 
they  are  generally  marked  by  a  tendinous  intersection  at  their  lower 
part. 

Relations. — By  its  external  surface,  with  the  sterno-hyoid,  omo- 
hyoid, and  sterno-mastoid  muscle ;  by  its  internal  surface,  with  the 
trachea  and  inferior  thyroid  veins,  with  the  thyroid  gland,  the  lower 
part  of  the  larynx,  the  sheath  of  the  common  carotid  artery  and 
internal  jugular  vein,  with  the  subclavian  vein  and  vena  innominata, 
and  on  the  right  side  with  the  arteria  innominata.  The  middle  thy- 
roid vein  lies  along  its  inner  border. 

The  Ihyro-hyoideus  is  tlic  continuation  upwards  of  the  sterno-thy- 
roid muscle.     It  arises  from  the  oblique  line  on  the  thyroid  cartilage. 


OMO-HYOIDEUS ELEVATORS  OF  THE  OS  HYOIDES.  161 

and  is  inserted  into  the  lower  border  of  the  body  and  great  cornu  of 
the  OS  hyoides. 

Relations. — By  its  external  surface  with  the  sterno-hyoid  and  omo- 
hyoid muscle;  by  its  internal  surf  ace  with  the  great  ala  of  the  thy- 
roid cartilage,  thethyro-hyoidean  membrane  and  the  superior  laryn- 
geal artery  and  nerve.^ 

The  omo-hyoideus  (uf^og,  shoulder)  is  a  double-bellied  muscle  pass- 
ing obliquely  across  the  neck  from  the  scapula  to  the  os  hyoides;  it 
forms  an  obtuse  angle  behind  the  sterno-mastoid  muscle,  by  means 
of  a  process  of  the  deep  cervical  fascia  which  is  connected  to  the 
inner  border  of  its  tendon.  It  arises  from  the  upper  border  of  the 
scapula,  and  from  the  transverse  ligament  of  the  supra-scapular 
notch,  and  is  inserted  into  the  lower  border  of  the  body  of  the  os 
hyoides. 

Relations. — By  its  superficial  surface  with  the  trapezius,  the  sub- 
clavius  and  clavicle,  the  deep  cervical  fascia  and  platysma  myoides, 
the  sterno-mastoid,  and  the  integument.  By  its  dee-p  surface  with 
the  brachial  plexus,  the  scaleni  muscles,  the  phrenic  nerve,  the  sheath 
of  the  common  carotid  artery  and  jugular  vein,  the  descendens  noni 
nerve,  and  the  sterno-thyroid,  and  thyro-hyoid  muscle.  The  scapu- 
lar portion  of  the  muscle  divides  the  great  posterior  triangle  into  a 
superior  or  occipital  triangle ;  and  an  inferior  or  subclavian  triangle, 
which  contains  the  subclavian  artery  and  brachial  plexus  of  nerves ; 
the  other  two  boundaries  of  the  latter  being  the  sterno-mastoid  in 
front  and  the  clavicle  below.  The  hyoid  portion  of  the  muscle, 
divides  the  great  anterior  triangle  into  an  inferior  carotid  triangle 
situated  below  the  muscle,  and  into  a  superior  triangle  which  lies 
above  the  muscle  and  is  again  subdivided  by  the  digastricus  muscle 
into  the  submaxillary  triangle  and  the  superior  carotid  triangle.  The 
other  two  boundaries  of  the  inferior  carotid  triangle,  are  the  middle 
line  of  the  neck  in  front  and  the  anterior  border  of  the  sterno-mas- 
toid behind.  The  other  boundaries  of  the  superior  carotid  triangle 
are  the  posterior  belly  of  the  digastricus  muscle  above  and  the  an- 
terior border  of  the  sterno-mastoid  behind. 

Actions. — The  four  muscles  of  this  group  are  the  depressors  of 
the  OS  hyoides  and  larynx.  The  three  former  drawing  these  parts 
downwards  in  the  middle  line,  and  the  two  omo-hyoidei  regulating 
their  traction  to  the  one  or  other  side  of  the  neck,  according  to  the 
position  of  the  head.  The  omo-hyoid  muscles  by  means  of  their 
connexion  with  the  cervical  fascia  are  rendered  tensors  of  that  por- 
tion of  the  deep  cervical  fascia  which  covers  in  the  lower  part  of 
the  neck,  between  the  two  sterno-mastoid  muscles. 

Third  Group. — Elevators  of  the  Os  Hyoides. 

Digastricus. 
Stylo-hyoid, 
Mylo-hyoid, 
Genio-hyoid, 
Genio-hyo-glossus. 
21 


162  ^  DIGASTEICUS STYLO-HYOIDEUS. 

Dissection. — These  are  best  dissected  by  placing  a  high  block  be- 
neath the  neck,  and  throwing  the  head  backwards.  The  integument 
has  been  already  dissected  away,  and  the  removal  of  the  cellular 
tissue  and  fat  brings  them  clearly  into  view. 

The  digastricus  {Slg,  twice,  yadrrj^  belly)  is  a  small  muscle  situated 
immediately  beneath  the  side  of  the  body  of  the  lower  jaw ;  it  is 
fleshy  at  each  extremity,  and  tendinous  in  the  middle.  It  arises 
from  the  digastric  fossa,  upon  the  inner  side  of  the  mastoid  process 
of  the  temporal  bone,  and  is  inserted  into  a  depression  on  the  inner 
side  of  the  lower  jaw,  close  to  the  symphysis.  The  middle  tendon 
is  held  in  connexion  with  the  body  of  the  os  hyoides  by  an  aponeu- 
rotic loop,  through  which  it  plays  as  through  a  pulley;  the  loop 
being  lubricated  by  a  synovial  membrane.  A  thin  layer  of  aponeu- 
rosis is  given  off  from  the  tendon  of  the  digastricus  at  each  side, 
which  is  connected  with  the  body  of  the  os  hyoides  and  forms  a 
strong  plane  of  fascia  between  the  anterior  portions  of  the  two  mus- 
cles.    This  fascia  is  named  the  supra-hyoidean. 

Relations. — By  its  superficial  surface  with  the  platysma  myoides, 
the  sterno-mastoid,  the  anterior  fasciculus  of  the  stylo-hyoid  muscle, 
the  parotid  gland,  and  submaxillary  gland.  By  its  deep  surface 
with  the  styloid  muscles,  the  hyo-glossus,  the  mylo-hyoid  muscle, 
the  external  carotid  artery,  the  lingual  and  the  facial  arteries,  the 
internal  carotid  artery,  the  jugular  vein,  and  the  hypoglossal  nerve. 
The  digastric  muscle  forms  the  two  inferior  boundaries  of  the  sub- 
maxillary triangle,  the  superior  boundary  being  the  side  of  the  body 
of  the  lower  jaw.  In  the  posterior  half  of  the  submaxillary  triangle 
is  situated  the  submaxillary  gland  and  the  facial  artery. 

The  stylo-hyoideus  is  a  small  and  slender  muscle  situated  in 
immediate  relation  with  the  posterior  belly  of  the  digastricus 
muscle,  being  pierced  by  its  tendon.  It  arises  from  the  middle  of 
the  styloid  process,  and  is  inserted  into  the  body  of  the  os  hyoides 
near  to  the  middle  hne. 

Relations. — By  its  superficial  surface  with  the  posterior  belly  of 
the  digastricus,  the  parotid  gland  and  submaxillary  gland ;  its 
deep  relations  are  similar  to  those  of  the  posterior  belly  of  the 
digastricus. 

The  digastricus  and  stylo-hyoideus  must  be  removed  from  their 
connexion  with  the  lower  jaw  and  os  hyoides,  and  turned  aside  in 
order  to  see  the  next  muscle. 

The  myh-hyoideus  (i^^vXyj,  mola,  i.  e.  attached  to  the  molar  ridge 
of  the  lower  jaw)  is  a  broad  triangular  plane  of  muscular  fibres, 
forming,  with  its  fellow  of  the  opposite  side,  the  inferior  wall  or 
floor  of  the  mouth.  It  arises  from  the  molar  ridge  on  the  lower 
jaw,  and  proceeds  obliquely  inwards  to  be  inserted  into  the  raphe 
of  the  two  muscles  and  into  the  body  of  the  os  hyoides  ;  the  raph^ 
is  sometimes  deficient  at  its  anterior  part. 

Relations. — By  its  superficial  or  inferior  surface,  with  the  pla- 
tysma myoides,  the  digastricus,  the  supra-hyoidean  fascia,  the  sub- 
maxillary gland  and  the  submental  artery.     By  its  deep  or  superior 


MUSCLES  OF  THE  TONGUE.  163 

surface,  with  the  genio-hyoideus,  the  genio-hyo-glossus,  the  hyo- 
glossus,  the  stylo-glossus,  the  gustatory  nerve,  the  hypo-glossal 
nerve,  Wharton's  duct,  the  subUngual  gland,  and  the  mucous  mem- 
brane of  the  floor  of  the  mouth. 

After  the  mylo-hyoideus  has  been  examined,  it  should  be  cut 
away  from  its  origin  and  insertion,  and  completely  removed.  The 
view  of  the  next  muscles  would  also  be  greatly  improved  by 
dividing  the  lower  jaw  a  little  to  one  side  of  the  symphysis,  and 
drawing  it  outwards,  or  by  removing  it  altogether  if  the  ramus 
have  been  already  cut  across  in  dissecting  the  internal  pterygoid 
muscle.  The  tongue  may  then  be  drawn  out  of  the  mouth  by 
means  of  a  hook. 

The  genio-hyoideus  (jivzm,  the  chin)  arises  from  a  small  tubercle 
upon  the  inner  side  of  the  symphysis  of  the  lower  jaw,  and  is  inserted 
into  the  upper  part  of  the  body  of  the  os  hyoides.  It  is  a  short  and 
slender  muscle,  very  closely  connected  with  the  border  of  the  fol- 
lowing. 

Relations. — By  its  superficial  or  inferior  surface,  with  the  mylo- 
hyoideus  ;  by  the  deep  or  superior  surface  with  the  lower  border  of 
the  genio-hyo-glossus. 

The  genio-hyo-glossus  (yXutftfa,  the  tongue)  is  a  triangular  muscle, 
narrow  and  pointed  at  its  origin  from  the  lower  jaw,  broad  and 
fan-shaped  at  its  attachment  to  the  tongue.  It  arises  from  a 
tubercle  immediately  above  that  of  the  genio-hyoideus,  and  spreads 
out  to  be  inserted  into  the  whole  length  of  the  tongue,  from  its  base 
to  the  apex,  and  into  the  body  of  the  os  hyoides. 

Relations. — By  its  inner  surface  with  its  fellow  of  the  opposite 
side.  By  its  outer  surface  with  the  mylo-hyoideus,  the  hyo-glossus, 
the  stylo-glossus,  lingualis,  the  subhngual  gland,  the  lingual  artery 
and  the  hypo-glossal  nerve.  By  its  upper  border  with  the  mucous 
membrane  of  the  floor  of  the  mouth,  by  the  side  of  the  frsenum 
linguae  ;  and  by  the  lower  border  with  the  genio-hyoideus. 

Actions. — The  whole  of  this  group  of  muscles  acts  upon  the  os 
hyoides,  when  the  lower  jaw  is  closed,  and  upon  the  lower  jaw 
when  the  os  hyoides  is  drawn  dowaiwards,  and  fixed  by  the 
depressors  of  the  os  hyoides  and  larynx.  The  genio-hyo-glossus  is, 
moreover,  a  muscle  of  the  tongue ;  its  action  upon  that  organ  shall 
be  considered  with  the  next  group. 

Fourth  Group. — Muscles  of  the  Tongue. 

Genio-hyo-glossus, 

Hyo-glossus, 

Lingualis, 

Stylo-glossus, 

Palato-o;lossus. 

These  are  already  exposed  by  the  preparation  we  have  just 
made;  there  remains,  therefore,  only  to  dissect  and  examine  them. 


164 


HYO-GLOSSUS LINGUALIS. 


i^,/ 


The  genio-hyo-glossus,  the  first  of  these  muscles,  has  been  described 
with  the  last  group. 

The  hijo-glossris  is  a  square-shaped  plane  of  muscle,  arising  from 
the  whole  length  of  the  great  cornu  and  from  the  body  of  the  os 
hyoides,and  inserted  between  the  stylo-glossus  and  lingualis  into 

the    side   of   the   tongue.     The 
^ig-  ■^'2*  direction    of  the  fibres  of  that 

portion  of  the  muscle  which 
arises  from  the  body  is  obliquely 
backwards ;  and  that  from  the 
great  cornu  obliquely  forwards  ; 
hence  they  are  described  by  Al- 
binus  as  two  distinct  muscles, 
under  the  names  of  the  basio- 
glossus,  and  cerato-glossus,  to 
which  he  added  a  third  fasci- 
culus, arising  from  the  lesser 
cornu,  and  spreading  along  the 
side  of  the  tongue,  the  chon- 
dro-glossus.  The  basio-glossus 
slightly  overlaps  the  cerato- 
glossus  at  its  upper  part,  and  is 
separated  from  it  by  the  trans- 
verse portion  of  the  stylo-glossus. 
Relations. — By  its  external 
surface  with  the  digastric  mus- 
cle, the  stylo-hyoideus,  stylo-glossus  and  mylo-hyoideus ;  with  the 
gustatory  nerve,  the  hypoglossal  nerve,  Wharton's  duct  and  the 
sublingual  gland.  By  its  internal  surface  with  die  middle  con- 
strictor of  the  pharynx,  and  Hngualis,  the  genio-hyo-glossus,  the 
lingual  artery,  and  the  glosso-pharyngeal  nerve. 

The  lingualis. — The  fibres  of  this  muscle  may  be  seen  towards 
the  apex  of  the  tongne,  issuing  from  the  interval  between  the  hyo- 
glossus  and  genio-hyo-glossus  ;  it  is  best  examined  by  removing  the 
preceding  muscle.  It  consists  of  a  small  fasciculus  of  fibres, 
running  longitudinally  from  the  base,  where  it  is  attached  to  the  os 
hyoides,  to  the  apex  of  the  tongue.  It  is  in  relation  by  its  under 
surface  with  the  ranine  artery. 

*  The  styloid  muscles  and  the  muscles  of  the  tongue.  1.  A  portion  of  the  temporal 
bone  of  the  left  side  of  the  skull,  including  the  styloid  and  mastoid  processes,  and  the 
meatus  auditorius  cxternus.  2,  2.  The  right  side  of  the  lower  jaw,  divided  at  its  sym- 
physis ;  the  left  side  having  been  removed.  3.  The  tongue.  4.  The  genio-hyoideus 
muscle.  .5.  The  genio-hyo-glossus.  6.  The  hyo-glossus  muscle ;  its  basio-glossus  por- 
tion. 7.  Its  cerato-glossus  portion.  8.  The  anterior  fibres  of  the  lingualis  issuing 
from  between  the  hyo-glossus  and  genio-hyo-glossus.  9.  The  stylo-glossus  muscle, 
with  a  small  portion  of  the  stylo-maxillary  ligament.  10.  The  stylo-hyoid.  11.  The 
stylo-pharyngeus  muscle.  12.  The  os  hyoides.  13.  The  thyro-hyoidean  membrane. 
14.  The  thyroid  cartilage.  1.5.  The  thyro-hyoideus  muscle  arising  from  the  oblique 
line  on  the  thyroid  cartilage.  16.  The  cricoid  cartilage.  17.  The  crico-lhyroidean 
rncmbranp,  through  which  the  operation  of  laryngotomy  is  performed.  18.  The 
trachea.     If).  The  commencement  of  the  oesophagus. 


MUSCLES  OF  THE  PHARYNX.  165 

The  stylo-glossus  arises  from  the  apex  of  the  styloid  process,  and 
from  the  stylo-maxillary  ligament ;  and  divides  upon  the  side  of  the 
tongue  into  two  portions,  one  transverse,  vv^hich  passes  transversely 
invs^ards  between  the  two  portions  of  the  hyo-glossus,  and  is  lost 
among  the  transverse  fibres  of  the  substance  of  the  tongue,  and 
another  longitudinal,  which  spreads  out  upon  the  side  of  the  tongue 
as  far  as  its  tip. 

Relations. — By  its  external  surface  with  the  internal  pterygoid 
muscle,  the  gustatory  nerve,  the  parotid  gland,  sublingual  gland,  and 
the  mucous  membrane  of  the  floor  of  the  tongue.  By  its  internal 
surface  with  the  tonsil,  the  superior  constrictor  muscle  of  the 
pharynx,  and  the  hyo-glossus  muscle. 

The  palaio-glossus*  passes  between  the  soft  palate,  and  the  side 
of  the  base  of  the  tongue,  forming  a  projection  of  the  mucous  mem- 
brane, which  is  called  the  anterior  pillar  of  the  soft  palate.  Its 
fibres  are  lost  superiorly  among  the  muscular  fibres  of  the  palato- 
pharyngeus,  and  inferiorly  among  the  fibres  of  the  stylo-glossus 
upon  the  side  of  the  tongue.  This  muscle  with  its  fellow  constitutes 
the  constrictor  isthmii  faucium. 

Actions, — The  genio-hyo-glossus  muscle  effects  several  movements 
of  the  tongue,  as  might  be  expected  from  its  extent.  When  the 
tongue  is  steadied  and  pointed  by  the  other  muscles,  the  posterior 
fibres  of  the  genio-hyo-glossus  would  dart  it  from  the  mouth,  while 
its  anterior  fibres  would  restore  it  to  its  original  position.  The 
whole  length  of  the  muscle  acting  upon  the  tongue,  would  render  it 
concave  along  the  middle  line,  and  form  a  channel  for  the  current 
of  fluid  towards  the  pharynx,  as  in  sucking.  The  apex  of  the 
tongue  is  directed  to  the  roof  of  the  mouth,  and  rendered  convex 
from  before  backwards  by  the  linguales.  The  hyo-glossi,  by 
drawing  down  the  sides  of  the  tongue,  render  it  convex  along  the 
middle  line.  It  is  drawn  upwards  at  its  base  by  the  palato-glossi, 
and  backwards  or  to  either  side  by  the  stylo-glossi.  Thus  the  whole 
of  the  complicated  movements  of  the  tongue  may  be  explained,  by 
reasoning  upon  the  direction  of  the  fibres  of  the  muscles,  and  their 
probable  actions. 

Fifth  Group. — Muscles  of  the  Pharynx. 

Constrictor  inferior. 
Constrictor  medius, 
Constrictor  superior, 
Stylo-pharyngeus, 
Palato-pharyngeus. 

Dissection. — To  dissect  the  pharynx,  the  trachea  and  oesophagus 
are  to  be  cut  through  at  the  lower  part  of  the  neck,  and  drawn 
upwards  by  dividing  the  loose  cellular  tissue  which  connects  the 

*  Called  also  constrictor  isthmii  faucium. — G. 


166  CONSTRICTORS  OF  THE  PHARYNX. 

pharynx  to  the  vertebral  column.  The  saw  is  then  to  be  applied 
behind  the  styloid  processes,  and  the  base  of  the  skull  sawn  through. 
The  vessels  and  loose  structures  should  be  removed  from  the  prepa- 
ration, and  the  pharynx  stuffed  with  tow  or  wool  for  the  purpose  of 
distending  it,  and  rendering  the  muscles  more  easy  of  dissection. 
The  pharynx  is  invested  by  a  proper  pharyngeal  fascia. 

The  constrictor  inferior,  the  thickest  of  the  three  muscles  of  this 
class,  arises  from  the  upper  rings  of  the  trachea,  from  the  cricoid 
and  the  side  of  the  thyroid  cartilage.  Its  fibres  spread  out  and  are 
inserted  into  the  fibrous  raphe  of  the  middle  of  the  pharynx,  the 
inferior  fibres  being  almost  horizontal,  and  the  superior  oblique, 
and  overlapping  the  middle  constrictor. 

Relations. — By  its  external  surface  Avith  the  anterior  surface  of 
the  vertebral  column,  the  longus  colli,  the  sheath  of  the  common 
carotid  artery,  the  sterno-thyroid  muscle,  the  thyroid  gland,  and 
some  lymphatic  glands.  By  its  internal  surface  with  the  middle 
constrictor,  the  stylo-pharyngeus,  the  palato-pharyngeus,  and  the 
mucous  membrane  of  the  pharynx.  By  its  lower  border,  near  to  the 
cricoid  cartilage,  it  is  in  relation  with  the  recurrent  nerve ;  and  by 
the  upper  border  with  the  superior  laryngeal  nerve. 

This  muscle  must  be  removed  before  the  next  can  be  examined. 

The  constrictor  medius  arises  from  the  great  cornu  of  the  os  hy- 
oides,  from  the  lesser  cornu,  and  from  the  stylo-hyoidean  ligament. 
It  radiates  from  its  origin  upon  the  side  of  the  pharynx,  the  lower 
fibres  descending  and  being  overlapped  by  the  constrictor  inferior, 
and  the  upper  fibres  ascending  so  as  to  cover  in  the  constrictor 
superior.  It  is  inserted  into  the  raphe  and  by  a  fibrous  aponeurosis 
into  the  basilar  process  of  the  occipital  bone. 

Relations. — By  its  external  surf  ace -with,  the  vertebral  column,  the 
longus  colli,  rectus  anticus  major,  the  carotid  vessels,  infeiior  con- 
strictor, hyo-glossus  muscle,  lingual  artery,  pharyngeal  plexus  of 
nerves,  and  some  lymphatic  glands.  By  its  internal  surface,  with 
the  superior  constrictor,  stylo-pharyngeus,  palato-pharyngeus,  and 
mucous  membrane  of  the  pharynx. 

The  upper  portion  of  this  muscle  must  be  turned  down,  to  bring 
the  whole  of  the  superior  constrictor  into  view ;  in  so  doing,  the 
stylo-pharyngeus  muscle  will  be  seen  passing  beneath  its  upper 
border. 

The  constrictor  superior  is  a  thin  and  quadrilateral  plane  of  muscu- 
lar fibres  arising  from  the  extremity  of  the  molar  ridge  of  the  lower 
jaw,  from  the  ptery go-maxillary  ligament,  and  from  the  lower  half 
of  the  internal  pterygoid  plate,  and  inserted  into  the  raphe  and 
basilar  process  of  the  occipital  bone.  Its  superior  fibres  are  arched 
and  leave  an  interval  between  its  upper  border  and  the  basilar  pro- 
cess which  is  deficient  in  muscular  fibres,  and  it  is  overlapped  in- 
feriorly  by  the  middle  constrictor.  Between  the  side  of  the  pharynx 
and  the  ramus  of  the  lower  jaw  is  a  triangular  interval,  the  maxillo- 
pharyngeal  space,  which  is  bounded  on  the  inner  side  by  the  supe- 


STYLO-PHARYNGETJS. 


167 


Fig-.  73* 


rior  constrictor  muscle ;  on  the  outer  side  by  the  internal  pterygoid 
muscle;  and  behind  by  the  rectus  anticus  major  and  vertebral 
column.  In  this  space  are  situated  the  internal  carotid  artery,  the 
internal  jugular  vein,  and  the  glosso-pharyngeal,  pneumogastric, 
spinal  accessory,  and  hypoglossal  nerve. 

Relations. — By  its  external  surface  with,  the  vertebral  column  and 
its  muscles,  behind;  with  the  vessels  and  nerves  contained  in  the 
maxil/o-pharyngeal  space  laterally,  the  middle  constrictor,  stylo- 
pharyngeus,  and  tensor  palati  muscle.  By  its  internal  surface  with 
the  levator  palati,  palato-pharyngeus,  tonsil,  and  mucous  membrane 
of  the  pharynx,  the  pharyngeal  fascia  being  interposed. 

The  stylo-pharyngeus  is  a  long  and 
slender  muscle  arising  from  the  inner 
side  of  the  base  of  the  styloid  process : 
it  descends  between  the  superior  and 
middle  constrictor  muscles,  and  spreads 
out  beneath  the  mucous  membrane  of 
the  pharynx,  its  inferior  fibres  being 
inserted  into  the  posterior  border  of  the 
thyroid  cartilage. 

Relations. — By  its  external  surface 
with  the  stylo-glossus  muscle,  external 
carotid  artery,  parotid  gland,  and  the 
middle  constrictor.  By  its  internal 
surface  with  the  internal  carotid  artery, 
internal  jugular  vein,  superior  constric- 
tor, palato-pharyngeus,  and  mucous 
membrane.  Along  its  lower  border  is 
seen  the  glosso-pharyngeal'nerve  which 
crosses  it,  opposite  the  root  of  the  tongue. 

The  palato-pharyngeus  is  described  with  the  muscles  of  the  soft 
palate.  It  arises  from  the  soft  palate,  and  is  inserted  into  the  inner 
surface  of  the  pharynx,  and  posterior  border  of  the  thyroid -carti- 
lage. 

Actions. — The  three  constrictor  muscles  contract  upon  the  morsel 
of  food  as  soon  as  it  is  received  by  the  pharynx,  and  convey  it 
gradually  downwards  into  the  oesophagus.  The  stylo-pharyngei 
draw  the  pharynx  upwards  and  widen  it  laterally.  The  palato- 
pharyngei  also  draw  it  upwards,  and  narrow  the  opening  of  the 
fauces. 


*  A  side  view  of  the  muscles  of  the  pharynx.  1.  The  trachea.  2,  Tlie  cricoid  car- 
tilag^e.  3.  The  crico-thyroid  membrane.  4.  The  thyroid  cartilage.  5.  The  thyro- 
hyoidean  membrane.  6.  The  os  hyoides.  7.  The  stylo-hyoidean  ligament.  8.  The 
(Esophagus.  9.  The  inferior  constrictor.  10.  The  middle  constrictor.  11.  The  supe- 
rior constrictor.  12.  The  stylo-pharyngeus  muscle  passing  down  between  the  superior 
and  middle  constrictor.  13.  The  upper  concave  border  oftlie  superior  constrictor;  at 
this  point  the  muscular  fibres  of  the  pharynx  are  deficient.  14.  The  ptery go-maxillary 
ligament.  15.  The  buccinator  muscle.  16.  The  orbicularis  oris.  ]7.  The  mylo- 
hyoideus. 


168 


MUSCLES  OF  THE  SOFT  PALATE. 


Fig.  74.* 


Sixth,  Group. — Muscles  of  the  soft  Palate. 

Levator  palati, 
Tensor  palati, 
Azygos  uvulae, 
Palato-glossus, 
Palato-pharyngeus. 

Dissection. — To  examine  these  muscles,  the  pharnyx  must  be 
opened  from  behind,  and  the  mucous  membrane  carefully  removed 
from  off  the  posterior  surface  of  the  soft  palate. 

The  levator  palati,  a  moderately  thick  muscle,  arises  from  the 
extremity  of  the  petrous  bone  and  from  the  posterior  and  inferior 
aspect  of  the  Eustachian  tube,  and  passing  down  by  the  side  of  the 
posterior  nares  spreads  out  in  the  structure  of  the  soft  palate  as  far 
as  the  middle  line. 

Relations. — Externally  with  the  tensor  palati  and  superior  con- 
strictor muscle ;  internally  and  posteriorly  with  the  mucous  mem- 
brane of  the  pharynx  and  soft  palate ;  and  by  its  lower  border  with 
the  palato-pharyngeus. 

This  muscle  must  be  turned  down  from  its  origin  on  one  side, 

and  removed,  and  the  superior  con- 
strictor dissected  away  from  its 
pterygoid  origin,  to  bring  the  next 
muscle  into  view. 

The  tensor  palati  (circumflexus)  is 
a  slender  and  flattened  muscle ;  it 
arises  from  the  scaphoid  fossa  at  the 
base  of  the  internal  pterygoid  plate 
and  from  the  anterior  aspect  of  the 
Eustachian  tube.  It  descends  to  the 
hamular  process  around  which  it 
turns,  and  expands  into  a  tendinous 
aponeurosis,  which  is  inserted  into 
the  transverse  ridge  on  the  horizontal 
portion  of  the  palate  bone,  and  into  the  raphe. 

Relations. — By  its  external  surface  with  the  internal  pterygoid 

*The  muscles  of  the  soft  palate.  1.  A  transverse  section  through  the  middle  of  the 
base  of  the  skull,  dividing  the  basilar  process  of  the  occipital  bone  in  the  middle  line, 
and  the  petrous  portion  of  the  temporal  bone  at  each  side.  2.  The  vomer  covered  by 
mucous  membrane  and  separating  the  two  posterior  nares.  3,  3.  Eustachian  tubes.  4. 
The  levator  palati  muscle  of  the  left  side ;  the  right  has  been  removed.  5.  The  ha- 
mular process  of  the  internal  pterygoid  plate  of  the  left  side,  around  which  the  apo- 
ncuorosis  of  the  tensor  palati  is  seen  turning.  G.  The  pterygo-maxillary  ligament.  7. 
The  superior  constrictor  muscle  of  the  left  side,  turned  aside.  8.  The  ar.ygos  uvulas 
muscle,  fj.  The  internal  pterygoid  plate.  10.  The  external  pterygoid  plate.  11.  The 
tensor  palati  muscle.  12.  Its  aponeurosis  expanding  in  the  structure  of  the  soft  palate. 
13.  The  external  pteiygoid  muscle.  14.  The  attachments  of  two  pairs  of  muscles  cut 
short ;  the  superior  pair  belong  to  the  genio-hyo-glossi  muscles  ;  the  inferior  pair,  to 
the  genio-hyoidei.  1.5.  The  attachment  of  the  mylo-hyoideus  of  one  side  and  part  of 
the  opposite.  16.  The  anterior  attachments  of  the  digastric  muscles.  17.  The  de- 
pression  on  the  lower  jaw  corresponding  with  the  submaxillary  gland.  The  depression 
above  the  mylo-hyoideus,  on  which  the  number  15  rests,  corresponds  with  the  sub- 
lingual  gland. 


PALATO-GLOSSUS PAL  ATO-  PHAR  YNGEUS .  169 

muscle ;  by  its  internal  surface  with  the  levator  palati,  internal 
pterygoid  plate  and  superior  constrictor.  In  the  soft  palate,  its  ten- 
dinous expansion  is  placed  in  front  of  the  other  muscles  and  in  con- 
tact with  the  mucous  membrane. 

The  azygos  uvula,  is  not  a  single  muscle,  as  might  be  inferred 
from  its  name,  but  a  pair  of  small  muscles  placed  side  by  side  in 
the  middle  line  of  the  soft  palate.  They  arise  from  the  spine  of 
the  palate  bone,  and  are  inserted  into  the  uvula.  By  their  anterior 
surface  they  are  in  contact  with  the  tendinous  expansion  of  the 
levatores  palati,  and  by  the  posterior  with  the  mucous  membrane. 

The  two  next  muscles  are  brought  into  view  throughout  the  whole 
of  their  extent,  by  raising  the  mucous  membrane  from  off  the  pillars 
of  the  soft  palate  at  each  side. 

The  palaio-glossus  (constrictor  isthmii  faucium)  is  a  small  fasci- 
culus of  fibres  that  arises  in  the  soft  palate,  and  descends  to  be 
inserted  into  the  side  of  the  tongue.  It  is  the  projection  of  this 
small  muscle  covered  by  mucous  membrane,  that  forms  the  anterior 
pillar  of  the  soft  palate.  It  has  been  named  constrictor  isthmii  fau- 
cium from  a  function  it  performs  in  common  with  the  palato- 
pharyngeus,  viz.  of  constricting  the  opening  of  the  fauces. 

Tiie  palato-pharyngeus  forms  the  posterior  pillar  of  the  fauces  ; 
it  arises  by  an  e:^panded  fasciculus  from  the  lower  part  of' the  soft 
palate  where  its  fibres  are  continuous  with  those  of  the  muscle  of 
the  opposite  side ;  and  is  inserted  into  the  posterior  border  of  the 
thyroid  cartilage.  This  muscle  is  broad  above  where  it  forms  the 
whole  thickness  of  the  lower  half  of  the  soft  palate,  narrow  in  the 
posterior  pillar,  and  again  broad  and  thin  in  the  pharynx  where  it 
spreads  out  previously  to  its  insertion.  ' 

Relations. — In  the  soft  palate  it  is  in  relation  with  the  mucous 
membrane  both  by  its  anterior  and  posterior  surface  ;  above,  with  the 
muscular  layer  formed  by  the  levator  palati,  and  below  with  the  mu- 
cous glands  situated  along  the  margin  of  the  arch  of  the  palate.  In 
the  posterior  pillar  of  the  palate,  it  is  surrounded  for  two-thirds  of 
its  extent  by  mucous  membrane.  In  the  pharynx,  it  is  in  relation 
by  its  outer  surface  with  the  superior  and  middle  constrictor  muscles, 
and  by  its  inner  surface  with  the  mucous  membrane  of  the  pharynx, 
the  pharyngeal  fascia  being  interposed. 

Actions. — The  azygos  uvulce  shortens  the  uvula.  The  levator 
palati  raises  the  soft  palate,  while  the  tensor  spreads  it  out  laterally 
so  as  to  form  a  septum  between  the  pharynx  and  posterior  nares 
during  deglutition.  Taking  its  fixed  point  from  below,  the  tensor 
palati  will  dilate  the  Eustachian  tube.  The  palato-glossus  and 
pharyngeus  constrict  the  opening  of  the  fauces,  and  by  drawing 
down  the  soft  palate  they  serve  to  press  the  mass  of  food  from  the 
dorsum  of  the  tongue  into  the  pharynx. 

22 


170 


PR^VEKTEBRAL  MUSCLES. 


Seventh  Group. — PrcBvertebral  Muscles. 

Rectus  anticus  majoi", 
Rectus  anticus  minor, 
Scalenus  anticus, 
Scalenus  posticus, 
Longus  colli. 

Dissection. — These  muscles  have  already  been  exposed,  by  the 
removal  of  the  face  from  the  anterior  aspect  of  the  vertebral 
column ;  all  that  is  further  needed  is  the  removal  of  the  fascia  by 
which  they  are  invested. 

The  rectus  anticus  major,  broad  and  thick  above,  and  narrow 
and  pointed  below,  arises  from  the  anterior  tubercles  of  the  trans- 
verse processes  of  the  third,  fourth,  fifth,  and  sixth  cervical  verte- 
brae, and  is  inserted  into  the  basilar  process  of  the  occipital  bone. 

Relations. — By  its  anterior  surface  with  the  pharynx,  the  internal 
carotid  artery,  internal  jugular  vein,  superior  cervical  ganglion, 
sympathetic  nerve,  pneumogastric,  and  spinal  accessory  nerve.  By 
its  posterior  surface  wi^h  the  longus  colli,  rectus  anticus  minor,  and 
superior  cervical  vertebree. 

The  rectus  anticus  minor  arises  from  the  anterior  border  of  the 

lateral  mass  of  the  atlas,  and  is  in- 
^^'  '^^*  serted  into   the   basilar   process ;    its 

fibres    being    directed    obliquely   up- 
wards and  inwards. 

Relations. — By  its  anterior  surface 
with  the  rectus  anticus  major,  and 
externally  with  the  superior  cervical 
ganglion  of  the  sympathetic.  By  its 
posterior  surface  with  the  articulation 
of  the  condyle  of  the  occipital  bone 
with  the  atlas,  and  with  the  anterior 
occipito-atloid  ligament. 

The  scalenus  anticus]  is  a  trian- 
gular muscle,  as  its  name  implies, 
situated  at  the  root  of  the  neck  and 
appearing  like  a  continuation  of 
the  rectus  anticus  major;  it  arises 
from  the  anterior  tubercles  of  the 
tej  transverse  processes  of  the  third, 
fourth,  fifth,  and  sixth  cervical  verte- 
broe,  and  is  inserted  into  the  tubercle 
upon  the  inner  border  of  the  first  rib. 

*  The  projvcTtebral  group  of  muscles  of  the  neck.  1.  The  rectus  anticus  major 
muscle.  2.  The  scalenus  anticus.  .3.  The  lower  part  of  the  longus  colli  of  the  i-ig-ht 
side  ;  it  is  concealed  superiorly  by  the  rectus  anticus  major.  4.  The  rectus  anticus 
minor.  5.  The  upper  portion  of  the  long-ns  colli  muf^cle.  6.  Its  lower  portion;  the 
figure  rests  upon  the  seventh  cervical  vertebra.  7.  The  scalenus  posticus.  8.  The 
rectus  lateralis  of  the  left  side.     9.  One  of  the  intertransversales  muscles. 

+  Horner  describes  three  scaleni,  viz. :  anticus,  medius,  and  posticus ;  the  anticus 


LONGUS  COLLI.  171 

Relations. — By  its  anterior  surf  ace  with  the  sterno-mastoid  and 
omo-hyoid  muscle,  with  the  cervicaHs  ascendens,  and  posterior  sca- 
pular artery,  with  the  phrenic  nerve,  and  with  the  subclavian  vein, 
by  which  it  is  separated  from  the  subclavius  muscle  and  clavicle. 
By  its  jjosterior  surface  with  the  nerves  which  go  to  form  the 
brachial  plexus,  and  below  with  the  subclavian  artery.  By  its 
inner  side  it  is  separated  from  the  longus  colli  by  the  vertebral  artery. 
Its  relations  with  the  subclavian  artery  and  vein  are  very  impor- 
tant, the  vein  being  before  and  the  artery  behind  the  muscle.* 

The  scalenus  'posticus  arises  from  the  posterior  tubercles  of  all 
the  cervical  vertebrte  excepting  the  first.  It  is  inserted  by  two 
fleshy  slips  into  the  first  and  second  ribs.  The  anterior  of  the  two 
slips  is  very  large,  and  occupies  all  the  surface  of  the  rib  between 
the  groove  for  the  subclavian  artery  and  the  tuberosity.  The  pos- 
terior is  small.  Hence  the  scalenus  medius  and  posticus  of  some 
anatomists. 

Relations. — By  its  anterior  surface  with  the  brachial  plexus  and 
subclavian  artery ;  posteriorly  with  the  levator  anguli  scapula,  cer- 
vicalis  ascendens,  transversalis  colli  and  sacro-lumbahs ;  internally 
with  the  first  intercostal  muscle,  the  first  rib,  the  inter-transverse 
muscles,  and  cervical  vertebra;  and  externally  with  the  sterno- 
mastoid,  omo-hyoid,  supra-scapular,  and  posterior  scapular  arteries. 

The  longus  colli  is  a  long  and  flat  muscle,  consisting  of  two 
portions.  The  upper  arises  from  the  anterior  tubercle  of  the  atlas, 
and  is  inserted  into  the  transverse  processes  of  the  third,  fourth, 
and  fifth  cervical  vertebra.  The  loicer  portion  arises  from  the 
bodies  of  the  second  and  third,  and  transverse  processes  of  the 
fourth  and  fifth,  and  passes  down  the  neck,  to  be  inserted  into  the 
bodies  of  the  three  lower  cervical  and  three  upper  dorsal  vertebrse. 
We  should  thus  arrange  these  attachments  in  a  tabular  form : 

Origin.  Insertion. 

Upper      ?  Af]  \  -^d,  4th,  and  5th  transverse 

portion.     3  '         '         '       \        processes. 

T                ')  2d  and  3d  bodies  C  3  lower  cervical    vertebree 

Lower       f  ^,,   „„  ,  ^,.   ,„„„_ _  > 


4th  and  5th  transverse  <      bodies 

3  upper  dorsal  bodies. 


>  4m  ana  om  transverse  < 
portion.      V  / 

^  )      processes     .         .      ( 


In  general  terms,  the  muscle  is  attached  to  the  bodies  and  trans- 
verse processes  of  the  five  superior  cervical  vertebrse  above,  and  to 
the  bodies  of  the  three  last  cervical  and  three  first  dorsal  below. 

Relations. — By  its  anterior  surface  with  the  pharynx,  oesophagus, 
the  sheath  of  the  common  carotid  internal  jugular  vein  and  pneumo- 
gastric  nerve,  the  sympathetic  nerve,  inferior  laryngeal  nerve,  and 

arising  from  the  fourth,  fifth,  and  sixth ;  the  medius  from  all  the  cervical  vertebrse ; 
and  the  posticus  from  the  fifth  and  sixth.  I  have  always  had  a  difficulty  in  separa- 
ting the  medius  and  posticus. — G. 

*  In  a  subject  dissected  in  the  school  of  tlie  Middlesex  Hospital  during  the  last 
winter,  by  Mr.  Joseph  Rogers,  the  subclavian  artery  of  the  left  side  was  placed  with 
the  vein  in  front  of  the  scalenus  anticus  muscle. 


172  MUSCLES  OF  THE  TRUNK. 

inferior  thyroid  artery.     By  its  posterior  surface  it  rests  upon  the 
cervical  and  upper  dorsal  vertebrae. 

Actions. — The  rectus  anticus  major  and  minor  preserve  the  equi- 
librium of  the  head  upon  the  atlas ;  and  acting  conjointly  with  the 
lonpus  colli,  they  flex  and  rotate  the  head  and  the  cervical  portion 
of  the  vertebral  column.  The  scaleni  muscles,  taking  their  fixed 
point  from  below,  are  flexors  of  the  vertebral  column ;  and,  from 
above,  elevators  of  the  ribs,  and  therefore  inspiratory  muscles. 

Eighth  Group. — Muscles  of  the  Larynx. 

These  muscles  are  described  with  the  anatomy  of  the  larynx,  in 
Chapter  X. 

MUSCLES  OF  THE  TRUNK. 

The  muscles  of  the  trunk  may  be  subdivided  into  four  natural 
groups ;  viz. 

1.  Muscles  of  the  back. 

2.  Muscles  of  the  thorax. 

3.  Muscles  of  the  abdomen. 

4.  Muscles  of  the  perineum. 

1.  Muscles  of  the  back. — The  region  of  the  back,  in  consequence  of 
its  extent,  is  common  to  the  neck,  the  upper  extremities,  and  the 
abdomen.  The  muscles  of  which  it  is  composed  are  numerous, 
and  may  be  arranged  into  six  layers. 

First  Layer.  Transversalis  colli, 

Trapezius,  Trachelo-mastoideus, 

Latissimus  dorsi.  Complexus. 

Second  Layer.  Fifth  Layer. 

Levator  anguli  scapulae,  (Dorsal  Group.) 

Rhomboideus  minor,  Semi-spinalis  dorsi, 

Rhomboideus  major.  Semi-spinahs  colli. 

Third  Layer.  (Cervical  Group.) 

Serratus  posticus  superior.  Rectus  posticus  major, 

Serratus  posticus  inferior,  Rectus  posticus  minor, 

Splenius  capitis,  Rectus  laterahs, 

Splenius  colli.  Obhquus  inferior, 

Fourth  Layer.  Obhquus  superior. 

(Dorsal  Group).  ^^^^^  ^^y^""' 

Sacro  lumbalis,  Multifidus  spinas, 

Longissimus  dorsi,  Levatores  costarum, 

Spinalis  dorsi.  Supra-spinalcs, 

(Cervical  Group.)  Inter-spinales, 

Cervicalis  ascendens,  Inter-transversales. 


MUSCLES  OF  THE  BACK.  173 


First  Layer. 

Dissection. — The  muscles  of  this  layer  are  to  be  dissected  by 
making  an  incision  along  the  middle  line  of  the  back,  from  the 
tubercle  on  the  occipital  bone  to  the  coccyx.  From  the  upper 
point  of  this  incision  carry  a  second  along  the  side  of  the  neck,  to 
the  middle  of  the  clavicle.  Inferiorly,  an  incision  must  be  made 
from  the  extremity  of  the  sacrum,  along  the  crest  of  the  ilium,  to 
about  its  middle.  For  convenience  of  dissection,  a  fourth  may  be 
carried  from  the  middle  of  the  spine  to  the  acromion  process.  The 
integument  and  superficial  fascia,  together,  are  to  be  dissected  off 
the  muscles,  in  the  course  of  their  fibres,  over  the  whole  of  this 
region. 

The  trapezius  muscle  (trapezium,  a  quadrangle  with  unequal 
sides)  arises  from  the  superior  curved  line  or  semicircular  ridge,  of 
the  occipital  bone,  from  the  ligamentum  nucha;,  supra-spinous 
ligament,  and  spinous  processes  of  the  last  cervical  and  all  the 
dorsal  vertebrae.  The  fibres  converge  from  these  various  points, 
and  are  inserted  into  the  scapular  third  of  the  clavicle,  the  acromion 
process,  and  the  whole  length  of  the  upper  border  of  the  spine  of  the 
scapula.  The  inferior  fibres  become  tendinous  near  to  the  scapula, 
and  glide  over  the  triangular  surface  at  the  posterior  extremity  of 
its  spine,  upon  a  bursa  mucosa.  When  the  trapezius  is  dissected 
on  both  sides,  the  two  muscles  resemble  a  trapezium,  or  diamond- 
shaped  quadrangle,  on  the  posterior  part  of  the  shoulders :  hence 
the  muscle  was  formerly  named  cucuUaris  (cucullus,  a  monk's  cowl.) 
The  cervical  and  upper  part  of  the  dorsal  portion  of  the  muscle  is 
tendinous  at  its  origin,  and  forms,  with  the  muscle  of  the  opposite 
side,  a  kind  of  tendinous  ellipse. 

Relations. — By  its  superficial  surface  with  the  integument  and 
superficial  fascia,  to  which  it  is  closely  adherent  by  its  cervical  por- 
tion, loosely  by  its  dorsal  portion.  By  its  deep  surface,  from  above 
downwards,  with  the  complexus,  splenius,  levator  anguli  scapulae, 
supra-spinatus,  a  small  portion  of  the  serratus  posticus  superior, 
rhomboideus  minor,  rhomboideus  major,  intervertebral  aponeurosis 
which  separates  it  from  the  erector  spinas,  and  with  the  latissimus 
dorsi.  The  anterior  border  of  the  cervical  portion  of  this  muscle 
forms  the  posterior  boundary  of  the  posterior  triangle  of  the  neck. 
The  clavicular  insertion  of  the  muscle  sometimes  advances  to  the 
middle  of  the  clavicle,  or  as  far  as  the  outer  border  of  the  sterno- 
mastoid,  and  occasionally  it  has  been  seen  to  overlap  the  latter. 
This  is  a  point  of  much  importance  to  be  borne  in  mind  in  the 
operation  for  ligature  of  the  subclavian  artery.  The  spinal  accessory 
nerve  passes  beneath  the  anterior  border,  near  to  the  clavicle,  pre- 
viously to  its  distribution  to  the  muscle. 

The  Ugamentum  nuchge  is  a  thin  cellulo-fibrous  layer  extended 
from  the  tubercle  and  spine  of  the  occipital  bone,  to  the  spinous 
process  of  the  seventh   cervical   vertebra,  where  it  is  continuous 


174  LATISSIMUS  DORSI RHOMBOIDETJS  MINOR, 

with  the  supra-spinous  hgament.  It  is  connected  with  the  spinous 
processes  of  the  rest  of  the  cervical  vertebrje,  with  the  exception  of 
the  atlas,  by  means  of  a  small  fibrous  slip  which  is  sent  off  by  each. 
It  is  the  analogue  of  an  important  elastic  ligament  in  animals. 

The  Utissmus  dorsi  muscle  covers  the  whole  of  the  lower  part  of 
the  back  and  loins.  It  arises  from  the  spinous  processes  of  the 
six  inferior  dorsal  vertebrae,*  from  all  the  lumbar  and  sacral 
spinous  processes,  from  the  posterior  third  of  the  crest  of  the  ilium, 
and  from  the  three  lower  ribs;  the  latter  origin  takes  place  by  mus- 
cular slips,  which  indigitate  with  the  external  oblique  muscle  of  the 
abdomen.  The  fibres  from  this  extensive  origin  converge  as  they 
ascend,  and  cross  the  inferior  angle  of  the  scapula;  they  then  curve 
around  the  lower  border  of  the  teres  major  muscle,  and  terminate 
in  a  short  quadrilateral  tendon,f  which  lies  in  front  of  the  tendon  of 
the  teres,  and  is  inserted  into  the  bicipital  groove.  A  synovial 
bursa  is  interposed  between  the  muscle  and  the  lower  angle  of  the 
scapula,  and  another  between  its  tendon  and  that  of  the  teres  major. 
The  muscle  frequently  receives  a  small  fasciculus  from  the  scapula 
as  it  crosses  its  inferior  angle. 

Relations. — By  its  superficial  surface  with  the  integument  and 
superficial  fascia ;  the  latter  is  very  dense  and  fibrous  in  the  lumbar 
region ;  and  with  the  trapezius.  By  its  deep  surface,  from  below 
upwards,  with  the  erector  spinee,  serratus  posticus  inferior,  inter- 
costal muscles  and  ribs,  rhomboideus  major,  inferior  angle;  of  the 
scapula  and  teres  major.  The  latissimus  dorsi  with  the  teres  major 
forms  the  posterior  border  of  the  axilla. 

Second  Layer. 

Dissection. — This  layer  is  brought  into  view  by  dividing  the  two 
preceding  muscles  near  to  their  insertion,  and  turning  them  to  the 
opposite  side. 

The  levator  anguli  scapulce  arises  by  distinct  slips,  from  the  pos- 
terior tubercles  of  the  transverse  processes  of  the  four  upper  cervical 
vertebrse,  and  is  inserted  into  the  upper  angle  and  posterior  border 
of  the  scapula,  as  far  as  the  triangular  smooth  surface  at  the  root  of 
its  spine. 

Relations. — By  its  superficial  surface  with  the  trapezius,  sterno- 
mastoid,  and  integument.  By  its  deep  surface  with  the  splenius 
colli,  transversahs  colli,  cervicahs  ascendens,  scalenus  posticus,  and 
serratus  posticus  superior.  The  tendons  of  origin  are  interposed 
between  the  attachments  of  the  scalenus  posticus  in  front  and  the 
splenius  colli  behind. 

The  rhomboideus  minor  (rhombus,  a  parallelogram  with  four 
equal  sides)  is  a  narrow  slip  of  muscle,  detached  from  the  rhomboi- 

*  Horner  says  seven. — G. 

t  A  small  muscular  fasciculus  from  the  pectoralis  major  is  sometimes  found  connected 
with  this  tendon. 


MUSCLES  OF  THE  BACK. 


175 


deus  major  by  a  slight  cellular  interspace.  It  arises  from  the  spi- 
nous process  of  the  last  cervical  vertebra  and  ligamentum  nuchas, 
and  is  inserted  into  the  edge  of  the  triangular  surface,  on  the  pos- 
terior border  of  the  scapula. 

Fig.  76.* 


I 


^^^x; 


*  The  first  and  second  and  part  of  the  third  layer  of  muscles  of  the  back ;  the  first 
layer  being-  shown  upon  the  right,  and  the  second  on  the  left  side.  1.  The  trapezius 
muscle.  2.  The  tendinous  portion  which,  with  a  corresponding  portion  in  the  opposite 
muscle,  forms  the  tendinous  ellipse  on  the  back  of  the  neck.  3.  The  acromion  pro- 
cess and  spine  of  the  scapula.  4.  The  latissimus  dorsi  muscle .  5.  The  deltoid.  6. 
The  muscles  of  the  dorsum  of  the  scapula,  infra-spinatus,  teres  minor,  and  teres  major, 
7.  The  external  oblique  muscle.  8.  The  gluteus  medius.  9.  The  glutei  maximi.  10. 
The  levator  anguli  scapulae.  11.  The  rhomboidcus  minor.  12.  The  rhomboideus 
major.  13.  The  splenius  capitis  ;  the  muscle  immediately  above,  and  overlaid  by  the 
splcnius,  is  the  complexus.  14.  The  splenius  colli,  only  partially  seen ;  the  common 
origin  of  the_splenius  is  seen  attaclied  to  the  spinous  processes  below  the  lower  border 
of  the  rhomboideus  major.  15.  The  vertebral  aponeurosis.  16.  The  serratus  posticus 
inferior.  17.  The  supra-spinatus  muscle.  18.  TJie  infra-spinatus.  19.  The  teres 
minor  muscle.  20.  The  teres  major.  21.  The  long  head  of  the  triceps,  passing 
between  the  teres  minor  and  major  to  the  upper  arm.  22.  The  serratus  magnus,  pro- 
ceeding forwards  from  its  origin  at  the  base  of  the  scapula.  23.  The  internal  oblique 
muscle. 


176  EHOMBOIDEI SERRA.TI. 

The  rliomhoideus  major  arises  from  the  spinous  processes  of  the 
four  upper  dorsal  vertebrae  and  from  the  supra-spinous  hgament ;  it 
is  inserted  into  the  posterior  border  of  the  scapula  as  far  as  its 
inferior  angle.  The  upper  and  middle  portion  of  the  insertion  is 
effected  by  means  of  a  tendinous  arch. 

Relations. — By  their  superficial  surface  the  two  rhomboid  mus- 
cles are  in  relation  with  the  trapezius,  and  the  rhomboideus  major 
with  the  latissimus  dorsi  and  integument.  By  their  deep'  sujfiace 
they  cover  in  the  serratus  posticus  superior,  part  of  the  erector 
spinse,  the  intercostal  muscles  and  ribs. 

Third  Layer. 

Dissection. — The  third  layer  consists  of  muscles  which  arise  from 
the  spinous  processes  of  the  vertebral  column,  and  pass  outwards. 
It  is  brought  into  view  by  dividing  the  levator  anguli  scapulae  near 
its  insertion,  and  reflecting  the  two  rhomboid  muscles  upwards 
from  their  insertion  into  the  scapula.  The  latter  should  be  removed 
altogether. 

The  serratus  posticus  superior  is  situated  at  the  upper  part  of  the 
thorax ;  it  arises  from  the  ligamentum  nuchas,  and  from  the  spinous 
process  of  the  last  cervical  and  two  upper  dorsal  vertebrae ;  it  is 
inserted  by  four  serrations  into  the  upper  border  of  the  second, 
third,  fourth,  and  fifth  ribs. 

Relations. — By  its  superficial  surface  with  the  trapezius,  rhom- 
boideus major  and  minor,  and  serratus  magnus.  By  its  deep  sur- 
face with  the  splenius,  the  upper  part  of  the  erector  spinae,  the 
intercostal  muscles  and  ribs. 

The  serratus  posticus  inferior  arises  from  the  spinous  processes  of 
the  two  last  dorsal  and  two  upper  lumbar  vertebras,  and  is  inserted 
by  four  serrations  into  the  lower  border  of  the  four  lower  ribs. 

Relations. — By  its  superficial  surface  with  the  latissimus  dorsi,  its 
tendinous  origin  being  inseparably  connected  with  the  aponeurosis  of 
that  muscle.  By  its  deep  surface  with  the  aponeurosis  of  the  obli- 
quus  internus,  with  which  it  is  also  closely  adherent ;  with  the 
erector  spinae,  the  intercostal  muscles  and  lower  ribs.  The  upper 
border  is  continuous  with  a  thin  tendinous  layer,  the  vertebral 
aponeurosis.  This  aponeurosis  consists  of  longitudinal  and  trans- 
verse fibres,  and  extends  the  whole  length  of  the  thoracic  region. 
It  is  attached  mesially  to  the  spinous  processes  of  the  dorsal  verte- 
bras, and  externally  to  the  angles  of  the  ribs ;  superiorly  it  is  con- 
tinued upwards  beneath  the  serratus  posticus  superior,  with  the 
lower  border  of  which  it  is  sometimes  connected.  It  serves  to  bind 
down  the  erector  spinae,  and  separates  it  from  the  superficial 
muscles. 

The  serratus  posticus  superior  must  ha  removed  from  its  origin 
and  turned  outwards,  to  bring  into  view  the  whole  extent  of  the 
splenius  muscle. 

The  splenius  muscle  is  single  at  its  origin,  but  divides  soon  after 
into  two  portions,  which  are  destined  to  distinct  insertions.     It 


MUSCLES  OP  THE  BACK.  177 

arises  from  the  lower  half  of  the  ligamentum  nuchas,  from  the 
spinous  process  of  the  last  cervical  vertebra,  and  from  the  spinous 
processes  of  the  six  upper  dorsal*  and  supra-spinous  ligament ;  it 
divides  as  it  ascends  the  neck  into  the  splenius  capitis  and  colli. 
The  splenius  capitis  is  inserted  into  the  rough  surface  of  the  occi- 
pital bone  between  the  two  semicircular  ridges,  and  into  the  mas- 
toid portion  of  the  temporal  bone. 

The  splenitis  colli  is  inserted  into  the  posterior  tubercles  of  the 
transverse  processes  of  the  three  or  four  upper  cervical  vertebrae. 

Relations. — By  its  superficial  surface  with  the  trapezius,  sterno- 
mastoid,  levator  anguli  scapula;,  rhomboideus  minor  and  major, 
and  serratus  posticus  superior.  By  its  deep  surface  with  the 
spinahs  dorsi,  longissimus  dorsi,  semi-spinahs  colli,  complexus, 
trachelo-mastoid,  and  transversalis  colli.  The  tendons  of  insertion 
of  the  splenius  colli  are  interposed  between  the  insertions  of  the 
levator  anguli  scapulae  in  front,  and  the  transversaUs  colli  behind. 

The  splenii  of  opposite  sides  of  the  neck  leave  between  them  a 
triangular  interval,  in  which  the  complexus  is  seen. 

Fourth  Layer. 

Dissection. — The  two  serrati  and  two  splenii  must  be  removed 
by  cutting  them  away  from  their  origins  and  insertions,  to  bring 
the  fourth  layer  into  view. 

Three  of  these  muscles,  viz.  sacro-lumbalis,  longissimus  dorsi, 
and  spinalis  dorsi,  are  associated  under  the  name  of  erector  spinse. 
They  occupy  the  lumbar  and  dorsal  portion  of  the  back.  The 
remaining  four  are  situated  in  the  cervical  region. 

The  sacro-lumbalis  and  longissimus  dorsi  arise  by  a  common 
origin  from  the  posterior  third  of  the  crest  of  the  ihum,  from  the 
posterior  surface  of  the  sacrum,  and  from  the  lumbar  vertebrae: 
opposite  the  last  rib  a  hne  of  separation  begins  to  be  perceptible 
between  the  two  muscles.  The  sacro-lumhalis  is  inserted  by  sepa- 
rate tendons  into  the  angles  of  the  six  lower  ribs.  On  turning  the 
muscle  a  little  outwards,  a  number  of  tendinous  sHps  will  be  seen 
taking  their  orgin  from  the  ribs,  and  terminating  in  a  muscular 
fasciculus,  by  which  the  sacro-lumbalis  is  prolonged  to  the  upper 
part  of  the  thorax.  This  is  the  musculus  accessorius  ad  sacro-lum- 
balem :  it  arises  from  the  angles  of  the  six  lower  ribs,  and  is 
inserted  by  separate  tendons  into  the  angles  of  the  six  upper  ribs. 

The  longissimus  dorsi  is  inserted  into  all  the  ribs,  between  their 
tubercles  and  angles.f 

The  spinalis  dorsi  arises  from  the  spinous  processes  of  the  two 
upper  lumbar  and  two  lower  dorsal  vertebrae,  and  is  inserted  into 
the  spinous  processes  of  all  the  upper  dorsal  vertebrae ;  the  two 
muscles  form  an  ellipse,  which  appears  to  enclose  the  spinous  pro- 
cesses of  all  the  dorsal  vertebrae. 

*  Horner  makes  it  to  arise  but  from  four  dorsal  vertebras. — G. 

t  It  is  also  inserted  into  the  ends  of  the  transverse  processes  of  all  the  dorsal  verte- 
brae.— G, 

23 


178 


FOURTH  LAYER. 


Fiff.  77  * 


i^t 


Relations. — The  erector  spinse  muscle  is  in  relation  by  its  super- 
ficial surface  (in  the  lumbar  region)  with  the  conjoined  aponeurosis 

of  the  transversalis  and  internal  oblique 
muscle,  which  separates  it  from  the  apo- 
neurosis of  the  serratus  posticus  inferior, 
and  longissimus  dorsi;  (in  the  dorsal 
region)  with  the  vertebral  aponeurosis, 
which  separates  it  from  the  latissimus 
dorsi,  trapezius,  and  serratus  posticus 
superior,  and  with  the  splenius.  By  its 
deep  surface  (in  the  lumbar  region)  with 
the  multifidus  spinoe,  transverse  processes 
of  the  lumbar  vertebras,  and  with  the 
middle  layer  of  the  aponeurosis  of  the 
transversalis  abdominis,  which  separates 
it  from  the  quadratus  lumborum ;  (in  the 
dorsal  region)  with  the  multifidus  spinse, 
semi-spinalis  dorsi,  levatores  costarum, 
intercostal  muscles,  and  ribs  as  far  as 
their  angles.  Internally  or  mesially  with 
the  multifidus  spinse,  and  semi-spinalis 
dorsi,  which  separate  it  from  the  spinous 
processes  and  arches  of  the  vertebrae. 

The  two  layers  of  aponeurosis  of  the 
transversalis  abdominis,  together  with  the 
spinal  column  in  the  lumbar  region,  and 
the  vertebral  aponeurosis  with  the  ribs 
and  spinal  column  in  the  dorsal  region, 
form  a  complete  osseo-aponeurotic  sheath 
for  the  erector  spinas. 

Cervical  Group. — The  cervicalis  as- 
cendensf  is  the  continuation  of  the  sacro- 
lumbalis  upwards  into  the  neck.  It  arises  from  the  angles  of  the 
four  upper  ribs,  and  is  inserted  by  slender  tendons  into  the  posterior 
tubercles  of  the  transverse  processes  of  the  four  lower  cervical 
vertebra;. 

Relations. — By  its  superficial  surface  with  the  levator  anguli  sca- 
pulae ;  by  its  deep  surface  with  the  upper  intercostal  muscles  and 
ribs,  and  with  the   intertransverse   muscles ;   externally  with  the 


*  The  fourth  and  fifth,  and  part  of  the  sixth  layer  of  the  muscles  of  the  back.  1.  The 
common  origin  of  the  erector  spinoe  muscle.  2.  The  sacro-lumbalis.  3.  The  longissi- 
mus dorsi.  4.  The  spinalis  dorsi.  5.  The  cervicalis  ascendcns.  6.  The  transversalis 
colli.  7.  The  trachclo-mastoideus.  8.  The  complcxus.  9.  The  transversalis  colli, 
showing- its  origin.  10.  The  semispinalis  dorsi.  11.  The  semjspinalis  colli.  12.  The 
rectus  posticus  minor.  13.  The  rectus  posticus  major.  14.  The  obliquus  superior. 
1.5.  The  obliquus  inferior.  Ifi.  The  multifidus  spina3.  17.  The  levatores  costarum. 
18.  Intertransversales.     19.  The  quadratus  lumborum. 

+  Called  commonly  the  cervicalis  desccndens. — G. 


MUSCLES  OF  THE  BACK.  179 

scalenus  posticus ;  and  internally  with  the  transversalis  colli.  The 
tendons  of  insertion  are  interposed  between  the  attachments  of  the 
scalenus  posticus  and  transversalis  colli. 

The  transversalis  colli  would  appear  to  be  the  continuation  up- 
wards into  the  neck  of  the  longissimus  dorsi ;  it  arises  from  the 
transverse  processes  of  the  third,  fourth,  fifth,  and  sixth  dorsal  ver- 
tebrse,  and  is  inserted  into  the  posterior  tubercles  of  the  transverse 
processes  of  the  four  or  five  inferior  cervical  vertebrae. 

Relations. — By  its  superficial  surface  with  the  levator  anguli  sca- 
pulae, splenius  and  longissimus  dorsi.  By  its  deep  surface  with  the 
complexus,  trachelo-mastoideus  and  vertebras  ;  externally  with  the 
musculus  accessorius  ad  sacro-lumbalem,  and  cervicalis  ascendens; 
internally  with  the  trachelo-mastoideus  and  complexus.  The  tendons 
of  insertion  of  this  muscle  are  interposed  between  the  tendons  of  in- 
sertion of  the  cervicalis  ascendens  on  the  outer  side,  and  of  origin  of 
the  trachelo-mastoid  on  the  inner  side. 

The  trachelo-mastoid  is  likewise  a  continuation  upwards  from  the 
longissimus  dorsi.  It  is  a  very  slender  and  delicate  muscle,  arising 
from  the  transverse  processes  of  the  four  upper  dorsal,  and  four 
lower  cervical  vertebrse,  and  inserted  into  the  mastoid  process  to 
the  inner  side  of  the  digastric  fossa. 

Relations. — The  same  as  those  of  the  preceding  muscle,  except- 
ing that  it  is  interposed  between  the  transversahs  colli  and  the  com- 
plexus. Its  tendons  of  attachment  are  the  most  posterior  of  those 
which  are  connected  with  the  posterior  tubercles  of  the  transverse 
processes  of  the  cervical  vertebrae. 

The  complexus  is  a  large  muscle,  and  with  the  splenius  forms  the 
great  bulk  of  the  back  of  the  neck.  It  crosses  the  direction  of  the 
splenius,  arising  from  the  transverse  processes  of  the  four  upper 
dorsal,*  and  from  the  transverse  and  articular  processes  of  the  four 
lower  cervical  vertebrae,  and  is  inserted  into  the  rough  surface  on 
the  occipital  bone  between  the  two  curved  lines,  near  to  the  occipital 
spine.  A  portion  of  the  complexus  muscle  is  named  hiventer  cervicis, 
from  consisting  of  a  central  tendon,  with  two  fleshy  bellies. 

Relations. — By  its  superficial  surface  with  the  trapezius,  splenius, 
trachelo-mastoid,  transversalis  colli,  and  longissimus  dorsi.  By  its 
deep  surface  with  the  semi-spinahs  dorsi  and  colli,  the  recti  and 
obliqui.  It  is  separated  from  its  fellow  of  the  opposite  side  by  the 
iigamentum  nuchae,  and  from  the  semi-spinalis  colli  by  the  profunda 
cervicis  artery,  and  princeps  cervicis  branch  of  the  occipital,  and 
by  the  posterior  cervical  plexus  of  nerves. 

Fifth  Layer. 

Dissection. — The  muscles  of  the  preceding  layer  are  to  be  re- 
moved by  dividing  them  transversely  through  the  middle,  and  turn- 

*  Horner  describes  its  origin  from  seven  dorsal  and  four  cervical. — G. 


180  FIFTH  LAYER. 

ing  one  extremity  upwards,  the  other  downwards.  In  this  way  the 
whole  of  the  muscles  of  the  fourth  layer  may  be  got  rid  of,  and  the 
remaining  muscles  of  the  spine  brought  into  a  state  to  be  examined. 

The  semi-spinales  muscles  are  connected  with  the  transverse  and 
spinous  processes  of  the  vertebras,  spanning  one-half  of  the  vertebral 
column,  hence  their  name  semi-spinales. 

The  semi-spinalis  dorsi  arises  from  the  transverse  processes  of  the 
six  lower  dorsal  vertebrae,  and  is  inserted  into  the  spinous  processes 
of  the  four  upper  dorsal,  and  two  lower  cervical  vertebrae. 

The  semi-spinalis  colli  arises  from  the  transverse  processes  of  the 
four  upper  dorsal  vertebrae,  and  is  inserted  into  the  spinous  processes 
of  the  four  upper  cervical  vertebrae,  commencing  with  the  axis. 

Relations. — By  their  superficial  surface  the  semi-spinales  are  in  re- 
lation from  below  upwards  with  the  spinalis  dorsi,  longissimus  dorsi, 
complexus,  splenius,  and  with  the  profunda  cervicis  and  princeps 
cervicis  artery,  and  posterior  cervical  plexus  of  nerves.  By  their 
deep  surface  with  the  raultifidus  spinas  muscle. 

Occipital  Group. — This  group  of  small  muscles  is  intended  for  the 
varied  movements  of  the  cranium  on  the  atlas,  and  the  atlas  on  the 
axis.     They  are  extremely  pretty  in  appearance. 

The  rectus  posticus  major  arises  from  the  spinous  process  of  the 
axis,  and  is  inserted  into  the  inferior  curved  line,  on  the  occipital 
bone. 

The  rectus  posticus  minor  arises  from  the  spinous  tubercle  of  the 
atlas,  and  is  inserted  into  the  rough  surface  on  the  occipital  bone, 
beneath  the  inferior  curved  line. 

The  rectus  latercdis  is  extended  between  the  transverse  process  of 
the  atlas  and  the  occipital  bone ;  it  arises  from  the  transverse  pro- 
cess of  the  atlas,  and  is  inserted  into  the  rough  surface  of  the  occi- 
pital bone,  external  to  the  condyle. 

The  ohliquus  inferior  arises  from  the  spinous  process  of  the  axis, 
and  passes  obliquely  outwards  to  be  inserted  into  the  extremity  of 
the  transverse  process  of  the  atlas. 

The  ohliquus  superior  arises  from  the  extremity  of  the  transverse 
process  of  the  atlas,  and  passes  obliquely  inwards  to  be  inserted  into 
the  rough  surface  of  the  occipital  bone,  between  the  curved  lines. 

Relations. — By  their  superficial  surface  the  recti  and  obliqui  are 
in  relation  with  a  strong  aponeurosis  which  separates  them  from  the 
complexus.  By  their  deep  surface  with  the  atlas  and  axis,  and  their 
articulations.  The  rectus  posticus  major  partly  covers  in  the  rectus 
minor. 

The  rectus  lateralis  is  in  relation  by  its  anterior  surface  with  the 
internal  jugular  vein,  and  by  its  posterior  surface  with  the  vertebral 
artery. 

Sixth  Layer. 

Dissection. — The  semi-spinales  muscles  must  both  be  removed  to 
obtain  a  good  view  of  the  multifidus  spinae  which  lies  beneath  them, 


MUSCLES  OF  THE  BACK.  181 

and  fills  up  the  concavity  between  the  spinous  and  transverse  pro- 
cesses, the  whole  length  of  the  vertebral  column. 

The  multifidus  spines  consists  of  a  great  number  of  fleshy  fasciculi, 
extending  between  the  transverse  and  spinous  processes  of  the  verte- 
brae, from  the  sacrum  to  the  axis.  Each  fasciculus  ai^ises  from  a 
transverse  process,  and  is  inserted  into  the  spinous  process  of  the 
first  or  second  vertebra  above. 

Relations. — By  its  sufeijicial  surface  with  the  longissimus  dorsi, 
semi-spinalis  dorsi,  and  semi-spinalis  colU.  By  its  deep  surface  with 
the  arches  and  spinous  processes  of  the  vertebral  column,  and  in  the 
cervical  region  with  the  ligamentum  nuchse. 

The  levatores  costarum,  twelve  in  number  on  each  side,  arise  from 
the  transverse  processes  of  the  dorsal  vertebrse,  and  pass  obliquely 
outwards  and  downwards  to  be  inserted  into  the  rough  surface  be- 
tween the  tubercle  and  angle  of  the  rib  below  them.  The  first  of 
these  muscles  arises  from  the  transverse  process  of  the  last  cervical 
vertebra,  and  the  last  from  that  of  the  eleventh  dorsal. 

Relations. — By  their  superficial  surface  with  the  longissimus  dorsi 
and  sacro-lumbalis.  By  their  deep  surface  with  the  intercostal 
muscles  and  ribs. 

The  supra- spinales  are  little  fleshy  bands  lying  on  the  spinous 
processes  of  the  vertebrse  in  the  cervical  region. 

The  inter-spinales  are  a  succession  of  little  pairs  of  muscles,  lying 
between  the  bifid  tubercles  of  the  spinous  processes  of  the  cervical 
vertebrse.  There  are  five  pairs  of  these  muscles ;  the  first  being 
situated  between  the  axis  and  third  vertebra,  and  the  last  between 
the  last  cervical  and  first  dorsal. 

The  inter-transversales  are  also  arranged  in  pairs,  and  pass  be- 
tween the  bifid  tubercles  of  the  transverse  processes  of  the  cervical 
vertebrse. 

The  inter-transversales,  situated  between  the  atlas  and  the  occipi- 
tal bone,  are  the  recti  laterales.  They  are  sometimes  found  in  the 
lumbar  regions. 

Relations. — In  front  with  the  rectus  anticus  major  and  longus 
colli ;  and  behind  by  the  muscles  of  the  back  of  the  neck.  They  are 
separated  from  each  other  by  the  anterior  branch  of  the  cervical 
nerves,  and  by  the  vertebral  artery  and  veins. 

With  regard  to  the  origin  and  insertion  of  the  muscles  of  the  back, 
the  student  should  be  informed  that  no  regularity  attends  their  at- 
tachments. At  the  best,  a  knowledge  of  their  exact  connexions, 
even  were  it  possible  to  retain  it,  would  be  but  a  barren  information, 
if  not  absolutely  injurious,  as  tending  to  exclude  more  valuable 
learning.  I  have  therefore  endeavoured  to  arrange  a  plan,  by  which 
they  may  be  more  easily  recollected,  by  placing  them  in  a  tabular 
form,  that  the  student  may  see  at  a  single  glance,  the  origin  and  in- 
sertion of  each,  and  compare  the  natural  grouping  and  similarity  of 
attachments  of  the  various  layers.  In  this  manner  also  their  actions 
will  be  better  comprehended,  and  learnt  with  greater  facility. 


182  SIXTH   LAYER. 

Actions. — The  upper  fibres  of  the. trapezius  draw  the  shoulder  up- 
wards and  backwards  ;  the  middle  fibres,  directly  backwards ;  and 
the  lower,  downwards  and  backwards.  The  lower  fibres  also  act 
by  .producing  rotation  of  the  scapula  upon  the  chest.  If  the  shoulder 
be  fixed  the  upper  fibres  will  flex  the  spine  towards  the  correspond- 
ing side.  The  latissimus  dorsi  is  a  muscle  of  the  arm,  drawing  it 
backwards  and  downwards,  and  at  the  same  time  rotating  it  in- 
wards ;  if  the  arm  be  fixed,  the  latissimus  dorsi  will  draw  the  spine 
to  that  side,  and  raising  the  lower  ribs  be  an  inspiratory  muscle ; 
and  if  both  arms  be  fixed,  the  two  muscles  will  draw  the  whole 
trunk  forwards,  as  in  climbing  or  walking  on  crutches.  The  levator 
anguli  scapula  lifts  the  upper  angle  of  the  scapula,  and  with  it  the 
entire  shoulder,  and  the  rhomboidei  carry  the  scapula  and  shoulder 
upwards  and  backwards. 

The  serrati  are  respiratory  muscles  acting  in  opposition  to  each 
other — the  serratus  posticus  superior  drawing  the  ribs  upwards,  and 
thereby  expanding  the  chest ;  and  the  inferior,  drawing  the  lower 
ribs  downwards  and  diminishing  the  cavity  of  the  chest.  The  former 
is  an  inspiratory,  the  latter  an  expiratory  muscle.  The  splenii 
muscles  of  one  side  draw  the  vertebral  column  backwards  and  to 
one  side,  and  rotate  the  head  towards  the  corresponding  shoulder. 
The  muscles  of  opposite  sides  acting  together,  will  draw  the  head 
directly  backwards.  They  are  the  natural  antagonists  of  the  sterno- 
mastoid  muscles. 

The  sacro-lumhalis  with  its  accessory  muscle,  the  longissimus  dorsi 
and  spinalis  dorsi,  are  known  by  the  general  term  of  erector  spince, 
which  sufficiently  expresses  their  actions.  They  keep  the  spine, 
supported  in  the  vertical  position  by  their  broad  origin  from  below, 
and  by  means  of  their  insertion  by  distinct  tendons  into  the  ribs  and 
spinous  processes.  Being  made  up  of  a  number  of  distinct  fasciculi, 
which  alternate  in  their  actions,  the  spine  is  kept  erect  without 
fatigue,  even  when  they  have  to  counterbalance  a  corpulent  abdomi- 
nal developement.  The  continuations  upwards  of  these  muscles  into 
the  neck  preserve  the  steadiness  and  uprightness  of  that  region. 
When  the  muscles  of  one  side  act  alone,  the  neck  is  rotated  upon 
its  axis.  The  complexus,  by  being  attached  to  the  occipital  bone, 
draws  the  head  backwards,  and  counteracts  the  muscles  on  the 
anterior  part  of  the  neck.     It  assists  also  in  the  rotation  of  the  head. 

The  semi-spinales  and  multifidus  spince  muscles  act  directly  on 
the  vertebra;,  and  contribute  to  the  general  action  of  supporting  the 
vertebral  column  erect. 

The  four  little  muscles  situated  between  the  occiput  and  the  two 
first  vertebroe,  effect  the  various  movements  between  these  bones ; 
the  recti  producing  the  antcro-postcrior  actions,  and  the  ohliqui  the 
rotary  motions  of  the  atlas  on  the  axis. 

The  actions  of  the  remaining  muscles  of  the  spine,  the  supra  and 
inter-spinales  and  inter-transversales,  are  expressed  in  tlieir  names. 
They  approximate  tlicir  attachments  and  assist  tlic  more  powerful 
muscles  in  preserving  the  erect  position  of  the  body. 


MUSCLES  OF  THE  BACK.  183 

The  levatores  costarum  raise  the  posterior  parts  of  the  ribs,  and 
are  probably  more  serviceable  in  preserving  the  articulation  of  the 
ribs  from  dislocation,  than  in  raising  them  in  inspiration. 

In  examining  the  following  table,  the  student  will  observe  the 
constant  recurrence  of  the  number  four  in  the  origin  and  insertion 
of  the  muscles.  Sometimes  the  four  occurs  at  the  top  or  bottom  of 
a  region  of  the  spine,  and  frequently  includes  a  part  of  two  regions, 
and  takes  two  from  each,  as  in  the  case  of  the  serrati.  Again,  he 
will  perceive  that  the  muscles  of  the  upper  half  of  the  table  take 
their  origin  from  spinous  processes,  and  pass  outwards  to  transverse, 
whereas  the  lower  half  arise  mostly  from  transverse  processes.  To 
the  student,  then,  we  commit  these  reflections,  and  leave  it  to  the 
peculiar  tenor  of  his  own  mind  to  make  such  arrangements  as  will 
be  best  retained  by  his  memory. 


184 


TABLE  OF  THE  ORIGIN  AND  INSERTION 


ORIGIN. 


Layers. 


Spinous  Processes. 


Transverse 
Processes. 


1st  Layer. 

Trapezius     .    .  < 

Latissiraus  dorsi  < 

2d  Layer. 

Levator  anguli  ) 

scapulse     .    .  \ 

Rhomboideus  / 

minor  ^ 

Rhomboideus  major 

3d  Layer. 

Serratus  posticus  / 

superior    .    .  C 

Serratus  posticus  ) 

inferior     .     .  J 

Splenius  capitis  / 

Splenius  colli    .  ) 

ilh  Layer. 


Sacro-lumbalis  .     . 

accessorius  ad 

sacro-lurabalem 


Longissimus  dorsi 
Spinalis  dorsi    . 
Cervicalis  ascendens 

Transversalis  colli 

Trachelo-mas-        j 
toideus ...     J 

Complexus    .    .    . 


5th  Layer. 
Semi-spinalis  dorsi 

Semi-spinalis  colli 

Rectus  posticus  maj. 
Ref:tus  posticus  min 
licctiis  litoralis .     . 
OhliquuK  inferior  . 
Obliquus  superior  . 


6</t  Jjayer. 
Multifidus  spinas 


Levatores  costarum 

Supra-spinales  .  . 
Intcr-spinales  .  . 
Inter-tranHversalcs 


last  cervical, 
12  dorsal  .    , 

6  lower  dorsal, 
5  lumbar  . 


lig.  nuchae, 

last  cervical  . 
4  upper  dorsal . 


3  lower 


occipital  bone,  and  ) 
ligamentum  nucha;  \ 

sacrum  and  ilium. 


4  upper  cervical 


lig.  nuchoe, 
last  cervical, 
2  upper  dorsal 

2  lower  dorsal, 
2  upper  lumbar 

lig.  nuchae, 
last  cervical, 
6  upper  dorsal 


2  lower  dorsal, 
2  upper  lumbar 


axis 
atlas 


cervical 
cervical 


3d,  4th,  5th, 

and  6th  dorsal 
4  upper  dorsal, 

4  lower  cervical 
4  upper  dorsal, 

4  lower  cervical 


6  lower  dorsal 
4  upper  dorsal 


atlas 
axis 


from  sacrum  to 
3d  cervical  . 

last  cervical  and 
eleven  dorsal 


cervical 


angles  of 
6  lower 


angles  of 
4  upper 


sacrum  and  ilium 


sacrum  and  lumbar  ) 
vertebne    .    .      \ 


OF  THE  MUSCLES  OF  THE  BACK. 


185 


INSERTION. 


Spinous  Processes. 


Transverse 
Processes. 


Ribs. 


8  upper  dorsal. 


4  upper  cervical, 


2d,  3d,  4th,  and  5th. 
4  lower  ribs. 


Additional. 


4  lower  cervical. 
4  lower  cervical. 


4  upper  dorsal, 
2  lower  cervical. 

4  upper  cervical, 
except  atlas. 


(  from  last  lumbar  to 
(      axis. 


atlas. 


angles  of  6  lower. 

angles  of  6  upper. 

all  the  ribs  between  the 
tubercles  and  angles. 


cervical, 
cervical. 


cervical. 


clavicle  and  spine  of 

the  scapula, 
posterior  bicipital  ridge 

of  the  humerus. 


angle  and  base  of  the 
scapula. 

base  of  the  scapula. 

base  of  the  scapula. 


occipital  and  mastoid 
portion  of  temporal 
bone. 


mastoid  process. 

occipital  bone  between 
the  curved  lines. 


occipital  bone, 
occipital  bone, 
occipital  bone. 

occipital  bone. 


all  the  ribs  between  the 
tubercles  and  angles. 


24 


186  sruscLEs  of  the  thorax. 


Muscles  of  the  Thorax. 

The  principal  muscles  situated  upon  the  thorax  belong  in  their 
actions  to  the  upper  extremity,  with  which  they  will  be  described. 
They  are  the  pectorahs  major  and  minor,  subclavius  and  serratus 
magnus.  The  true  thoracic  muscles  are  few  in  number,  and  apper- 
tain exclusively  to  the  actions  of  the  ribs ;  they  are,  the — 

Intercostales  externi, 
Intercostales  interni, 
Triangularis  sterni. 

The  intercostal  muscles  are  two  planes  of  muscular  and  tendinous 
fibres  directed  obliquely  between  the  adjacent  ribs  and  closing  the 
intercostal  spaces.  They  are  seen  partially  upon  the  removal  of 
the  pectoral  muscles,  or  upon  the  inner  surface  of  the  chest.  The 
triangularis  sterni  is  within  the  chest,  and  requires  the  removal  of  the 
anterior  part  of  the  thorax  to  bring  it  into  view. 

The  intercostales  externi,  eleven  on  each  side,  commence  pos- 
teriorly at  the  vertebral  column,  and  advance  forwards  to  the  costal 
cartilages  where  they  terminate  in  a  thin  aponeurosis  which  is  con- 
tinued onwards  to  the  sternum.  Their  fibres  are  directed  obliquely 
downwards  and  inwards,  pursuing  the  same  line  with  those  of  ihe 
external  oblique  muscle  of  the  abdomen.  They  are  thicker  than 
the  internal  intercostals. 

The  intercostales  interni,  also  eleven  on  each  side,  commence 
anteriorly  at  the  sternum,  and  extend  backwards  as  far  as  the  angles 
of  the  ribs,  whence  they  are  prolonged  to  the  vertebral  column  by  a 
thin  aponeurosis.  Their  fibres  are  directed  obliquely  downwards  , 
and  backwards,  and  correspond  in  direction  with  those  of  the  inter- 
nal oblique  muscle  of  the  abdomen.  The  two  muscles  cross  each 
other  in  the  direction  of  their  fibres. 

In  structure  the  intercostal  muscles  consist  of  an  admixture  of 
muscular  and  tendinous  fibres.  They  arise  from  the  two  lips  of  the 
lower  border  of  the  ribs,  the  external  from  the  outer  lip,  the  internal 
from  the  inner,  and  are  inserted  into  the  upper  border. 

Relations. — The  external  intercostals,  by  their  external  surface 
with  the  muscles  which  immediately  invest  the  chest,  viz.  with  the 
pectoralis  major  and  minor,  the  serratus  magnus,  serratus  posticus 
superior  and  inferior,  scalenus  posticus;  sacro-lumbalis,  and  lon- 
gissimus  dorsi,  with  their  continuations,  the  cervicalis  ascendens  and 
transversalis  colli ;  the  levatores  costarum,  and  the  obliquus  externus 
abdominis.  By  their  internal  surface  with  the  internal  intercostals, 
the  intercostal  vessels  and  nerves,  and  a  thin  aponeurosis,  and  pos- 
teriorly with  the  pleura.  The  internal  intercostals,  by  their  external 
surface  with  the  external  intercostals,  and  intercostal  vessels  and 
nerves;  by  their  internal  surface  with  the  pleura  costalis,  the  trian- 
gularis sterni  and  dia]:)ln'agm. 

Connected  with  the  internal  intercostals  are  a  variable  number  of 


MUSCLES   OF  THE  THORAX. 


187 


muscular  fasciculi  which  pass  from  the  inner  surface  of  one  rib  near 
its  middle  to  the  next  or  next  but  one  below ;  these  are  the  subcostal 
or  more  correctly  the  intracostal  muscles. 

Fig.  78.* 


*  The  muscles  of  the  anterior  aspect  of  the  trunk ;  on  the  left  side  the  superficial 
layer  is  seen,  and  on  the  rigfht  the  deeper  layer.  1.  The  pectoralis  major  muscle.  2. 
The  deltoid ;  the  interval  between  these  muscles  lodges  the  cephalic  vein.  3.  The 
anterior  border  of  the  latissimus  dorsi.  4.  The  serrations  of  the  serratus  magnus, 
5.  The  subclavius  muscle  of  the  right  side.  6.  The  pectoralis  minor.  7.  The  coraco- 
brachialis  muscle.  8.  Tlie  upper  part  of  the  biceps  muscle,  showing  its  two  heads. 
9.  The  coracoid  process  of  the  scapula.  10.  The  serratus  magnus  of  tlie  right  side. 
Jl.  The  external  intercostal  muscle  of  the  fifth  intercostal  space.  12.  The  external 
oblique  muscle.  13,  Its  aponeurosis;  the  median  line  to  the  right  of  this  number  is 
the  linea  alba ;  the  flexuous  line  to  its  left  is  the  linea  semilunaris  ;  and  the  transverse 
lines  above  and  below  the  number,  the  linea3  transversae,  of  which  there  were  only 
three  in  this  subject.  14.  Poupart's  ligament.  1.5.  TJie  external  abdominal  ring;  the 
margin  above  the  ring  is  the  superior  or  internal  pillar ;  the  margin  below  the  ring, 
the  inferior  or  external  pillar ;  the  curved  intercolumnar  fibres  are  seen  proceeding  up- 
wards from  Poupart's  ligament  to  strengthen  the  ring.  The  numbers  14  and  15  are 
situated  upon  the  fascia  lata  of  the  thigh;  the  opening  immediately  to  the  right  of  15 
is  the  saphenous  opening.  16.  The  rectus  muscle  of  the  right  side  brought  into  view 
by  the  removal  of  the  anterior  segment  of  its  sheath:  *  the  posterior  segment  of  its 
sheath  with  the  divided  edge  of  the  anterior  segment.  17.  The  pyramidalis  muscle. 
18.  The  internal  oblique  muscle.  19.  The  conjoined  tendon  of  the  internal  oblique 
and  transversalis  descending  behind  Poupart's  ligament  to  the  pectineal  line.  20.  The 
arch  formed  between  the  lower  curved  border  of  the  internal  oblique  muscle  and  Pou- 
part's ligament;  it  is  beneath  this  arch  that  the  spermatic  cord  and  hernia  pass. 


188  MUSCLES   OF  THE  ABDOMEN. 

The  triangularis  sterni,  situated  upon  the  inner  wall  of  the  front  of 
the  chest,  arises  by  a  thin  aponeurosis  from  the  side  of  the  sternum, 
ensiform  cartilage,  and  sternal  extremities  of  the  costal  cartilao-es ; 
and  is  inserted  by  fleshy  digitations  into  the  cartilages  of  the  third, 
fourth,  fifth  and  sixth  ribs,  and  often  into  that  of  the  second. 

Relations. — By  its  external  sivrface  with  the  sternum,  the  ensiform 
cartilage,  the  costal  cartilages,  internal  intercostal  muscles,  and  in- 
ternal mammary  vessels.  By  its  internal  surface  with  the  pleura 
costalis,  the  cellular  tissue  of  the  anterior  mediastinum  and  the  dia- 
phragm. 

Jlctions. — The  intercostal  muscles  raise  the  ribs  when  they  act 
from  above,  and  depress  them  when  they  take  their  fixed  point  from 
below.  They  are,  therefore,  both  inspiratory  and  expiratory  muscles. 
The  triangularis  sterni  draws  down  the  costal  cartilages,  and  is 
therefore  an  expiratory  muscle. 

Muscles  of  the  Abdomen. 

The  muscles  of  this  region  are  the — 

Obliquus  externus  (descendens), 

Obliquus  internus  (ascendens), 

Cremaster, 

Transversalis, 

Rectus, 

Pyramidalis, 

Quadratus  lumborum, 

Psoas  parvus, 

Diaphragm. 

Dissection. — The  dissection  of  the  abdominal  muscles  is  to  be 
commenced  by  making  three  incisions : — The  first,  vertical,  in  the 
middle  line,  from  over  the  lower  part  of  the  sternum  to  the  pubes ; 
the  second,  oblique,  from  the  umbilicus,  upwards  and  outwards,  to 
the  outer  side  of  the  chest,  as  high  as  the  fifth  or  sixth  rib ;  and  the 
third,  oblique,  from  the  umbilicus,  downwards  and  outwards,  to  the 
middle  of  the  crest  of  the  ihum.  The  three  flaps  included  by  these 
incisions  should  then  be  dissected  back  in  the  direction  of  the  fibres 
of  the  external  oblique  muscle,  beginning  at  the  angle  of  each.  The 
integument  and  superficial  fascia  should  be  dissected  off"  together  so 
as  to  expose  the  fibres  of  the  muscle  at  once. 

If  the  external  oblique  muscle  be  dissected  on  both  sides,  a  white 
tendinous  line  will  be  seen  along  tiie  middle  of  the  abdomen,  extend- 
ing from  the  ensiform  cartilage  to  the  os  pubis;  this  is  the  linea  alba. 
A  little  external  to  it,  on  each  side,  two  curved  lines  will  be  observed 
extending  from  the  sides  of  the  chest  to  the  os  pubis,  and  bounding 
the  recti  muscles :  these  are  the  lineai  semilunares.  Some  transverse 
lines,  linecB  Iransversce,  three  or  four  in  number,  connect  the  linese 
semilunares  with  the  linea  alba. 

The  external  oblique  muscle  {obliquus  externus  abdominis,  descen- 


MUSCLES  OF  THE  ABDOMEN.  189 

dens)  is  the  external  flat  muscle  of  the  abdomen.  Its  name  is  derived 
from  the  obliquity  of  its  direction,  and  the  descending  course  of  its 
fibres.  It  arises  by  fleshy  digitations  from  the  external  surface  of 
the  eight  inferior  ribs.  The  five  upper  digitations  being  received 
betM^een  corresponding  processes  of  the  serratus  magnus,  and  the 
three  lower  of  the  latissimus  dorsi;  it  spreads  out  into  a  broad 
aponeurosis,  which  is  inserted  into  the  outer  lip  of  the  crest  of  the 
ilium  for  one  half  its  length,  the  anterior  superior  spinous  process  of 
the  ilium,  spine  of  the  os  pubis,  pectineal  line,  front  of  the  os  pubis, 
and  linea  alba. 

The  lower  border  of  the  aponeurosis,  which  is  stretched  between 
the  anterior  superior  spinous  process  of  the  ilium  and  the  spine  of 
the  OS  pubis,  is  folded  inwards,  forming  Pozipart's  ligament ;  the  in- 
sertion into  the  pectineal  line  is  Gimbernafs  ligament. 

Just  above  the  crest  of  the  os  pubis  is  the  external  abdominal  ring, 
a  triangular  opening  formed  by  the  separation  of  the  fibres  of  the 
aponeurosis  of  the  external  oblique.  It  is  oblique  in  its  direction, 
and  corresponds  with  the  course  of  the  fibres  of  the  aponeurosis.  It 
is  bounded  below  by  the  crest  of  the  os  pubis ;  on  either  side,  by  the 
borders  of  the  aponeurosis,  which  are  called  fillars ;  and  above  by 
some  curved  fibres  (inter-columnar),  which  originate  from  Poupart's 
ligament,  and  cross  the  upper  angle  of  the  ring,  so  as  to  give  it 
strength.  The  external  pillar,  which  is  at  the  same  time  inferior, 
from  the  obliquity  of  the  opening  is  inserted  into  the  spine  of  the  os 
pubis ;  the  internal  or  superior  pillar  forms  an  interlacement  with  its 
fellow  of  the  opposite  side  over  the  front  of  the  symphysis  pubis. 
The  external  abdominal  ring  gives  passage  to  the  spermatic  cord 
in  the  male,  and  round  ligament  in  the  female ;  they  are  both  in- 
vested in  their  passage  through  it  by  a  thin  fascia  derived  from  the 
edges  of  the  ring,  and  called  inter- columnar  fascia,  or  fascia  sper- 
matica. 

The  pouch  of  inguinal  hernia,  in  passing  through  this  opening,  re- 
ceives the  inter-columnar  fascia,  as  one  of  its  coverings. 

Relations. — By  its  external  surface  with  the  superficial  fascia  and 
integument,  and  with  the  cutaneous  vessels  and  nerves,  particularly 
the  superficial  epigastric  and  superficial  circumflex  ilii  vessels.  It 
is  generally  overlapped  posteriorly  by  the  latissimus  dorsi.  By  its 
internal  surface  with  the  internal  oblique,  the  lower  part  of  the  eight 
inferior  ribs  and  intercostal  muscles,  the  cremaster,  the  spermatic 
cord  in  the  male,  and  the  round  ligament  in  the  female. 

The  external  oblique  is  now  to  be  removed  by  making  an  incision 
across  the  ribs,  just  below  its  origin,  to  its  posterior  border;  and 
another  along  Poupart's  ligament  and  the  crest  of  the  ilium.  Pou- 
part's ligament  should  be  left  entire,  as  it  gives  attachment  to  the 
next  muscles.  The  muscle  may  then  be  turned  forwards  towards 
the  hnea  alba,  or  removed  altogether. 

The  internal  oblique  muscle  {obliquus  int^rnus  abdominis,  ascen- 
dens)  is  the  middle  flat  muscle  of  the  abdomen.  It  arises  from  the 
outer  half  of  Poupart's  ligament,  from  the  middle  of  the  crest  of  the 


190  MUSCLES  OF  THE  ABUOHIEN. 

ilium  for  two-thirds  of  its  length,  and  by  a  thin  aponeurosis  from  the 
spinous  processes  of  the  lumbar  vertebrae.*  Its  fibres  diverge  from 
their  origin,  so  that  those  from  Poupart's  hgament  curve  down- 
wards, those  from  the  anterior  pan  of  the  crest  of  the  ilium  pass 
transversely,  and  the  rest  ascend  obliquely.  The  muscle  is  inserted 
into  the  pectineal  line,  crest  of  the  os  pubis,  linea  alba,  and  lower 
borders  of  the  five  inferior  ribs. 

Along  the  upper  three-fourths  of  the  linea  semilunaris,  the  aponeu- 
rosis of  the  internal  oblique  separates  into  two  lamellae,  which  pass 
one  in  front  and  the  other  behind  the  rectus  muscle  to  the  linea  alba, 
where  they  are  inserted ;  along  the  lower  fourth,  the  aponeurosis 
passes  altogether  in  front  of  the  rectus  without  separation.  The 
two  layers  which  thus  enclose  the  rectus,  form  for  it  a  partial 
sheath. 

The  lowest  fibres  of  the  internal  oblique  are  inserted  into  the  pec- 
tineal line  in  common  with  those  of  the  transversalis  muscle.  Hence 
the  tendon  of  this  insertion  is  called  the  conjoined  tendon  of  the  in- 
ternal oblique  and  transversalis.  This  structure  corresponds  with 
the  external  abdominal  ring,  and  forms  a  protection  to  what  would 
otherwise  be  a  weak  point  in  the  abdomen.  Sometimes  it  is  insuf- 
ficient to  resist  the  pressure  from  within,  and  becomes  forced  through 
the  external  ring :  it  then  forms  the  distinctive  covering  of  direct  in- 
guinal hernia. 

The  spermatic  cord  passes  beneath  the  arched  border  of  the  in- 
ternal oblique  muscle,  between  it  and  Poupart's  ligament.  During 
its  passage  some  fibres  are  given  off"  from  the  lower  border  of  the 
muscle,  which  accompany  the  cord  downwards  to  the  testicle,  and 
form  loops  around  it:  this  is  the  cremaster  muscle.  In  the  descent 
of  oblique  inguinal  hernia,  which  travels  the  same  course  with  the 
spermatic  cord,  the  cremaster  muscle  forms  one  of  its  coverings. 

The  cremaster,  considered  as  a  distinct  muscle,  arises  from  the 
middle  of  Poupart's  ligament,  and  forms  a  series  of  loops  upon  the 
spermatic  cord.  A  few  of  its  fibres  are  inserted  into  the  tunica 
vaginalis,  the  rest  ascend  along  the  inner  side  of  the  cord,  to  be  in- 
serted, with  the  conjoined  tendon,  into  the  pectineal  line  of  the  os 
pubis. 

Relations. — The  internal  oblique  is  in  relation  by  its  external  sur- 
face with  the  external  oblique,  latissimus  dorsi,  spermatic  cord  and 
external  abdominal  ring.  By  its  internal  surface  with  the  trans- 
versalis muscle,  the  fascia  transversalis,  the  internal  abdominal 
ring,  and  spermatic  cord.  By  its  lower  and  arched  border  with  the 
spermatic  cord,  forming  the  upper  boundary  of  the  spermatic  canal. 

The  cremaster  is  in  relation  by  its  external  surface  with  the 
aponeurosis  of  the  external  oblique  and  inter-columnar  fascia ;  and 
by  its  internal  surface  with  the  fascia  propria  of  the  spermatic 
cord. 

The  internal  oblique  muscle  is  to  be  removed  by  separating  it 

*  From  the  tlircc  inlciior  lumbar  spinous  processes  and  all  those  of  the  saerum. — G. 


MUSCLES  OF  THE   ABU03IEN.  191 

from  its  attachment  to  the  ribs  above,  and  to  the  crest  of  the  iUuni 
and  Poupart's  Hgament  below.  It  should  be  divided  behind  by  a 
vertical  incision  extending  from  the  last  rib  to  the  crest  of  the  ihum, 
as  its  lumbar  attachment  cannot  at  present  be  examined.  The 
muscle  is  then  to  be  turned  forwards.  Some  degree  of  care  will 
be  required  in  performing  this  dissection,  from  the  difficulty  of  dis- 
tinguishing between  this  muscle  and  the  one  beneath.  A  thin  layer 
of  cellular  tissue  is  all  that  separates  them  for  the  greater  part  of 
their  extent.  Near  the  crest  of  the  iUum  the  circumflex  ilii  artery 
ascends  between  the  two  muscles,  and  forms  a  valuable  guide  to 
their  separation.  Just  above  Poupart's  ligament  they  are  so  closely 
connected  that  it  is  impossible  to  divide  them. 

The  transversalis  is  the  internal  flat  muscle  of  the  abdomen ;  it  is 
transverse  in  the  direction  of  its  fibres,  as  is  implied  in  its  name.  It 
arises  from  the  outer  third  of  Poupart's  ligament,  from  the  internal 
lip  of  the  crest  of  the  iUum,  its  anterior  two  thirds ;  from  the  spinous 
and  transverse  processes  of  the  lumbar  vertebree,*  and  from  the  inner 
surfaces  of  the  six  inferior  ribs,  indigitating  with  the  diaphragm. 
Its  lower  fibres  curve  downwards,  to  be  inserted,  with  the  lower 
fibres  of  the  internal  oblique,  into  the  pectineal  line,  and  form  the 
conjoined  tendon.  Throughout  the  rest  of  its  extent  it  is  inserted 
into  the  crest  of  the  os  pubis  and  linea  alba.  The  loioer  fourth  of 
its  aponeurosis  passes  in  front  of  the  rectus  to  the  linea  alba ;  the 
upper  tliree-fourths,  with  the  posterior  lamella  of  the  internal  oblique, 
behind  it. 

The  posterior  aponeurosis  of  the  transversalis  divides  into  three 
lamellge  ; — anterior,  which  is  attached  to  the  bases  of  the  transverse 
processes  of  the  lumbar  vertebras;  middle,  to  the  apices  of  the  trans- 
verse processes ;  and  posterior,  to  the  apices  of  the  spinous  processes. 
The  anterior  and  middle  lamellae  enclose  the  quadratus  lumborum 
muscle ;  and  the  middle  and  posterior,  the  erector  spinee.  The  union 
of  the  posterior  lamella  of  the  transversalis  with  the  posterior  aponeu- 
rosis of  the  internal  oblique,  serratus  posticus  inferior,  and  latissimus 
dorsi,  constitutes  the  lumbar  fascia. 

Relations. — By  its  external  surface  with  the  internal  oblique,  the 
internal  surfaces  of  the  lower  ribs,  and  internal  intercostal  muscles. 
By  its  internal  surface  with  the  transversalis  fascia,  which  separates 
it  from  the  peritoneum,  with  the  psoas  magnus,  and  with  the  lower 
part  of  the  rectus  and  pyramidalis.  The  spermatic  cord  and  oblique 
inguinal  hernia  pass  beneath  the  lower  border,  but  have  no  direct  re- 
lation with  it. 

To  dissect  the  rectus  muscle,  the  sheath  should  be  opened  by  a 
vertical  incision  extending  from  over  the  cartilages  of  the  lower 
ribs  to  the  front  of  the  os  pubis.  The  sheath  may  then  be  dissected 
ofl'  and  turned  to  either  side :  this  is  easily  done  excepting  at  the 
linese  transversaj,  where  a  close  adhesion  subsists  between  the  muscle 

*  From  the  transverse  processes  of  the  last  dorsal  and  four  superior  lumbar  verte- 
brae.—G. 


192 


TRANSVEESALIS RECTUS. 


Fig.  79* 


and  the  external  boundary  of  the  sheath.     The  sheath  contains  the 
rectus  and  pyramidaUs  muscle. 

The  rectus  muscle  arises  by  a  flattened  tendon  from  the  crest  of 
the  OS  pubis,  and  is  inserted  into  the  cartilages  of  the  fifth,  sixth, 
and  seventh  ribs.     It  is  traversed  by  several  tendinous  zig-zag  lines, 

called  linese  transversa;.  One  of  these 
is  usually  situated  at  the  umbilicus, 
two  above  that  point,  and  sometimes 
one  below.  They  are  vestiges  of  the 
abdominal  ribs  of  reptiles,  and  very 
rarely  extend  completely  through  the 
muscle. 

Relations. — By  its  external  surface 
with  the  anterior  lamella  of  the  apo- 
neurosis of  the  internal  oblique,  below 
with  the  aponeurosis  of  the  transver- 
salis,  and  pyramidalis.  By  its  inter- 
nal surface  with  the  ensiform  carti- 
lage, the  cartilages  of  the  fifth,  sixth, 
seventh,  eighth  and  ninth  ribs,  with 
the  posterior  lamella  of  the  internal 
oblique,  the  peritoneum,  and  the  epi- 
gastric artery  and  veins. 

The  pyramidalis  muscle  arises  from 
the  crest  of  the  os  pubis  in  front  of 
the  rectus,  and  is  inserted  into  the 
linea  alba  at  about  midway  between 
the  umbilicus  and  the  pubis.     It  is 
enclosed  in  the  same  sheath  with  the 
rectus,!  and  rests  against  the  lower 
part  of  that  muscle.     This  muscle  is 
sometimes  wanting. 
The  rectus  may  now  be  divided  across  the  middle,  and  the  two 
ends  drawn  aside  for  the  purpose  of  examining  the  mode  of  forma- 
tion of  its  sheath. 

The  sheath  of  the  rectus  is  formed  in  front  for  the  upper  three- 
fourths  of  its  extent,  by  the  aponeurosis  of  the  external  oblique  and 
the  anterior  lamella  of  the  internal  oblique,  and  behind  by  the  poste- 


*  A  lateral  view  of  the  trunk  of  the  body,  showing  its  muscles,  and  particularly  the 
transversalis  abdominis.  1.  The  costal  origin  of  the  latissimus  dorsi  muscle.  2.  The 
serratus  magniis.  3.  The  upper  part  of  the  external  oblique  muscle  divided  in  the 
direction  licst  calculated  to  show  the  muscles  beneath  without  interfering  with  its  in- 
digifations  with  the  serratus  magnus,  4.  Two  of  the  external  intercostal  muscles. 
5.  Two  of  tlic  internal  intercostals.  6.  The  transversalis  muscle.  7.  Its  posterior 
aponeurosis.  8.  Its  anterior  aponeurosis  forming  the  most  posterior  layer  of  the  sheath 
of  the  rectus.  9.  The  lower  part  of  the  left  rectus  with  the  aponeurosis  of  the  trans- 
versalis passing  in  front.  10.  The  right  rectus  muscle.  11.  The  arched  opening  left 
between  the  lower  border  of  the  transversalis  muscle  and  Poupart's  ligament,  through 
which  the  spermatic  cord  and  hernia  pass.  12.  The  gluteus  maximus,  and  medius, 
and  tensor  vaginm  fcrnoris  muscles  invested  by  fascia  lata. 

t  This  is  not  precisely  the  fact,  as  there  is  a  separate  sheath  for  the  pyramidalis. — G. 


MUSCLES  OF  THE  ABDOMEN.  193 

rior  lamella  of  the  internal  oblique  and  the  aponeurosis  of  the  trans- 
versalis.  At  the  commencement  of  the  lower  fourth,  the  posterior 
wall  of  the  sheath  terminates  in  a  thin  curved  margin,  the  aponeu- 
roses of  the  three  muscles  passing  altogether  in  front  of  the  rectus. 

The  two  next  muscles  can  only  be  examined  when  the  whole  of 
the  viscera  are  removed.  To  see  the  quadratus  lumborum,  it  is  also 
necessary  to  divide  and  draw  aside  the  psoas  muscle  and  the  an- 
terior lamella  of  the  aponeurosis  of  the  transversalis. 

The  quadratus  lumborum  muscle  is  concealed  from  view  by  the 
anterior  lamella  of  the  aponeurosis  of  the  transversalis  muscle,  which 
is  inserted  into  the  bases  of  the  transverse  processes  of  the  lumbar 
vertebrae,  and  ligamentum  arcuatum  externum.  When  this  lamella 
is  divided,  the  muscle  will  be  seen  arising  from  the  last  rib,  and 
from  the  transverse  processes  of  the  four  upper  lumbar  vertebrae. 
It  is  inserted  into  the  crest  of  the  ilium.  If  the  muscle  be  cut  across 
or  removed,  the  middle  lamella  of  the  transversalis  will  be  seen 
attached  to  the  apices  of  the  transverse  processes ;  the  quadratus 
being;  enclosed  between  the  two  lamellas  as  in  a  sheath. 

Relations. — Enclosed  in  the  sheath  formed  by  the  transversalis 
muscle,  it  is  in  relation  in  front,  with  the  kidney,  the  colon,  the 
psoas  magnus  and  the  diaphragm.  Behind,  but  also  separated  by 
the  sheath,  with  the  erector  spinse. 

The  psoas  -parvus  arises  from  the  tendinous  arches  and  interverte- 
bral substance  of  the  last  dorsal  and  first  lumbar  vertebrae,  and  ter- 
minates in  a  long  slender  tendon  which  is  inserted  into  the  pectineal 
line  of  the  os  pubis.  The  tendon  is  continuous  by  its  outer  border 
with  the  iliac  fascia. 

Relations. — It  rests  upon  the  psoas  magnus,  and  is  covered  in  by 
the  peritoneum ;  superiorly  it  passes  beneath  the  hgamentum  arcu- 
atum of  the  diaphragm.     It  is  occasionally  wanting. 

Diaphragm. — ^To  obtain  a  good  view  of  this  important  inspiratory 
muscle,  the  peritoneum  should  be  dissected  from  its  under  surface. 
It  is  the  muscular  septum  between  the  thorax  and  abdomen,  and  is 
composed  of  two  portions,  a  greater  and  a  lesser  muscle.  The 
greater  muscle  arises  from  the  ensiform  cartilage ;  from  the  inner 
surfaces  of  the  six  inferior  ribs,  indigitating  with  the  transversalis ; 
and  from  the  ligamentum  arcuatum  externum  and  internum.  From 
these  points  which  form  the  internal  circumference  of  the  trunk,  the 
fibres  converge  and  are  inserted  into  the  central  tendon. 

The  ligamentum  arcuatum  externum  is  the  upper  border  of  the  an- 
terior lamella  of  the  aponeurosis  of  the  transversalis :  it  arches  across 
the  origin  of  the  quadratus  lumborum  muscle,  and  is  attached  by  one 
extremity  to  the  extremity  of  the  transverse  process  of  the  first  lum- 
bar vertebra,  and  by  the  other  to  the  apex  and  lower  margin  of  the 
last  rib. 

The  ligamentum  arcuatum  internum,  or  proprium,  is  a  tendinous 
arch  thrown  across  the  psoas  magnus  muscle  as  it  emerges  from 
the  chest.     It  is  attached  by  one  extremity  to  the  transverse  pro- 

25 


194 


BIArHEAGM. 


cess  of  the  first  lumbar  vertebra,  and  by  the  other  to  the  body  of  the 
second. 

Fig.  S0.« 


The  tendinous  centre  of  the  diaphragm  is  shaped  Hke  a  trefoil  leaf, 
of  which  the  central  leaflet  points  to  the  ensiform  cartilage,  and  is 
the  largest ;  the  lateral  leaflets,  right  and  left,  occupy  the  correspond- 
ing portions  of  the  muscle ;  the  right  being  the  larger  and  more 
rounded,  and  the  left  smaller  and  lengthened  in  its  form. 

Between  the  sides  of  the  ensiform  cartilage  and  the  cartilages  of 
the  adjoining  ribs,  is  a  small  triangular  space  where  the  muscular 
fibres  of  the  diaphragm  are  deficient.  This  space  is  closed  only  by 
peritoneum  on  the  side  of  the  abdomen,  and  by  pleura  within  the 
chest.  It  is  therefore  a  weak  point,  and  a  portion  of  the  contents  of 
the  abdomen  might,  by  violent  exertion,  be  forced  through  it,  pro- 
ducing phrenic,  or  diaphragmatic  hernia. 

The  lesser  muscle  of  the  diaphragm  takes  its  origin  from  the  bodies 


*  The  under  or  abdominal  side  of  the  diaphragm.  1,  2,  3.  The  greater  muscle ;  the 
figure  1  rests  upon  the  central  leaflet  of  the  tendinous  centre ;  the  number  2  on  the  left 
or  smallest  leaflet;  and  number  3  on  the  right  leaflet.  4.  The  thin  fasciculus  which 
arises  from  the  ensiform  cartilage ;  a  small  triangular  space  is  left  on  either  side  of  this 
fasciculus,  which  is  closed  only  by  the  serous  membranes  of  the  abdomen  and  chest. 
5.  The  ligamentum  arcuatum  externum  of  the  left  side.  6.  The  ligamentum  arcuatum 
internum.  7.  A  small  arched  opening  occasionally  found,  through  which  the  lesser 
splanchnic  nerve  passes.  8.  The  right  or  larger  tendon  of  the  lesser  muscle ;  a  muscu- 
lar fasciculus  from  this  tendon  curves  to  the  left  side  of  the  greater  muscle  between  the 
oesophageal  and  aortic  openings.  9.  Tlie  fourth  lumbar  vertebra.  10.  The  left  or 
shorter  tendon  of  the  lesser  muscle.  11.  The  aortic  opening  occupied  by  the  aorta, 
which  is  cut  short  off.  12.  A  portion  of  the  oesophagus  issuing  through  the  oesopha- 
geal opening.  13.  The  opening  for  the  inferior  vena  cava,  in  the  tendinous  centre  of 
the  diaphragm.  14.  The  psoas  magnus  muscle  passing  beneath  the  ligamentum 
arcuatum  internum  :  it  has  been  removed  on  the  opposite  side  to  show  the  arch  more 
distinctly.  15.  The  quadratus  lumborum  passing  beneath  the  ligamentum  arcuatum 
externum  ;  this  muscle  has  also  been  removed  on  the  left  side. 


DIAPIIRAG3I.  195 

of  the  lumbar  vertebrae  by  two  tendons.  The  right,  larger  and  longer 
than  the  left,  arises  from  the  anterior  surface  of  the  bodies  of  the 
second,  third,  and  fourth  vertebrte ;  and  the  left  from  the  side  of  the 
second  and  third.  The  tendons  form  two  large  fleshy  bellies  {crura), 
which  ascend  to  be  inserted  into  the  central  tendon.  The  inner 
fasciculi  of  the  two  crura  cross  each  other  in  front  of  the  aorta,  and 
again  diverge  to  surround  the  oesophagus,  so  as  to  present  the  appear- 
ance of  a  figure  of  eight.  The  anterior  fasciculus  of  the  decussation 
is  formed  by  the  right  crus. 

The  openings  in  the  diaphragm  are  three :  one,  quadrilateral,  in 
the  tendinous  centre,  at  the  union  of  the  right  and  middle  leaflets, 
for  the  passage  of  the  inferior  vena  cava;  a  muscular  opening  of  an 
elliptic  shape  formed  by  the  two  cr-ura,  for  the  transmission  of  the 
cesophagus  and  pneumogastric  nerves ;  and  a  third,  the  aortic,  which 
is  formed  by  a  tendinous  arch  thrown  from  the  tendon  of  one  crus 
to  that  of  the  other,  across  the  vertebral  column,  beneath  which  pass 
the  aorta,  the  iight  vena  azygos,  and  thoracic  duct.  The  great 
splanchnic  nerves  pass  through  openings  in  the  lesser  muscle  on 
each  side,  and  the  lesser  splanchnic  nerves  through  the  fibres  which 
arise  from  the  ligamentum  arcuatum  internum. 

Relations. — By  its  superior  surface  with  the  pleurae,  the  pericar- 
dium, the  heart,  and  the  lungs.  By  its  inferior  surface  with  the 
peritoneum ;  on  the  left  with  the  stomach  and  spleen ;  on  the  right 
with  the  convexity  of  the  liver ;  and  behind  with  the  kidneys,  the 
suprarenal  capsules,  the  duodenum,  and  the  solar  plexus.  By  its 
circumference  with  the  ribs  and  intercostal  muscles,  and  with  the 
vertebral  column. 

Actions. — The  external  oblique  muscle,  acting  singly,  would  draw 
the  thorax  towards  the  pelvis,  and  twist  the  body  to  the  opposite 
side.  Both  muscles,  acting  together,  would  flex  the  thorax  directly 
on  the  pelvis.  The  internal  oblique  of  one  side  draws  the  chest 
downwards  and  outwards :  both  together  bend  it  directly  forwards. 
Either  transversalis  muscle,  acting  singly,  will  diminish  the  size  of 
the  abdomen  on  its  own  side,  and  both  together  will  constrict  the 
entire  cylinder  of  the  cavity.  The  recti  muscles,  assisted  by  the 
pyramidales,  flex  the  thorax  upon  the  chest,  and,  through  the  me- 
dium of  the  hn£e  transversae,  are  enabled  to  act  when  their  sheath  is 
curved  inwards  by  the  action  of  the  trans  versales.  The  pyramidales 
are  tensors  of  the  linea  alba.  The  abdominal  are  expiratory  mus- 
cles, and  the  chief  agents  of  expulsion ;  by  their  action  the  fcetus  is 
expelled  from  the  uterus,  the  urine  from  the  bladder,  the  faeces  from 
the  rectum,  the  bile  from  the  gall-bladder,  the  ingesta  from  the  sto- 
mach and  bowels  in  vomiting,  and  the  mucous  and  irritating  sub- 
stances from  the  bronchial  tubes,  trachea,  and  nasal  passages  during 
coughing  and  sneezing.  To  produce  these  efforts  they  all  act 
together.  Their  violent  and  continued  action  produces  hernia ;  and, 
acting  spasmodically,  they  may  occasion  rupture  of  the  viscera. 
The  quadratus  lumborum  draws  the  last  rib  downwards,  and  is  an 
expiratory  muscle ;  it  also  serves  to  bend  the  vertebral  column  to 


196  MUSCLES  OF  THE  PERINEUM. 

one  or  the  other  side.  The  psoas  parvus  is  a  tensor  of  the  iUac 
fascia,  ami,  taking  its  fixed  origin  from  below,  it  may  assist  in  flex- 
ing the  vertebral  column  forw^ards.  The  diaphragm  is  an  inspira- 
tory muscle,  and  the  sole  agent  in  tranquil  inspiration.  When  in 
action,  the  muscle  is  drawn  downwards,  its  plane  being  rendered 
oblique  from  the  level  of  the  ensiform  cartilage,  to  that  of  the  upper 
lumbar  vertebra.  During  relaxation  it  is  convex,  and  encroaches 
considerably  on  the  cavity  of  the  chest,  particularly  at  the  sides, 
where  it  corresponds  with  the  lungs.  It  assists  the  abdominal  mus- 
cles powerfully  in  expulsion,  every  act  of  that  kind  being  preceded  or 
accompanied  by  a  deep  inspiration.  Spasmodic  action  of  the  dia- 
phragm produces  hiccough  and  sobbing,  and  its  rapid  alternation  of 
contraction  and  relaxation,  combined  with  laryngeal  and  facial 
movements,  laughing  and  crying. 

Muscles  of  the  Perineum. 

The  muscles  of  the  perineum  are  situated  in  the  outlet  of  the  pel- 
vis, and  consist  of  two  groups,  one  of  which  belongs  especially  to 
the  organs  of  generation  and  urethra,  the  other  to  the  termination 
of  the  alimentary  canal.  To  these  may  be  added  the  only  pair  of 
muscles  which  is  proper  to  the  pelvis,  the  coccygeus.  The  muscles 
of  this  region  in  the  male,  are  the 

Accelerator  urinse, 
Erector  penis, 
Transversus  perinei, 
Compressor  urethrse, 
Sphincter  ani, 
Levator  ani, 
Coccygeus. 

Dissection. — To  dissect  the  perineum,  the  subject  should  be  fixed 
in  the  position  for  lithotomy,  that  is,  the  hands  should  be  bound  to 
the  soles  of  the  feet,  and  the  knees  kept  apart.  An  easier  plan  is  the 
drawing  of  the  feet  upwards  by  means  of  a  cord  passed  through  a 
hook  in  the  ceiling.  Both  of  these  plans  of  preparation  have  for 
their  object  the  full  exposure  of  the  perineum.  And  as  this  is  a 
dissection  which  demands  some  degree  of  dehcacy  and  nice  manipu- 
lation, a  strong  light  should  be  thrown  upon  the  part.  Having  fixed 
the  subject,  and  drawn  the  scrotum  upwards  by  means  of  a  string 
or  hook,  carry  an  incision  from  the  base  of  the  scrotum  along  the 
ramus  of  the  pubis  and  ischium  and  tuberosity  of  the  ischium,  to  a 
point  parallel  with  the  apex  of  the  coccyx ;  then  describe  a  curve 
over  the  coccyx  to  the  same  point  on  the  o])posite  side,  and  continue 
the  incision  onwards  along  the  opposite  tuberosity,  and  along  the 
ramus  of"  the  ischium  and  of  the  pubis,  to  the  opposite  side  of  the 
scrotum,  where  the  two  extremities  may  be  connected  by  a  trans- 
verse incision.  This  incision  will  completely  surround  the  perineum, 
following  very  nearly  the  outline  of  its  boundaries.     Now  let  the  stu- 


MUSCLES  OF  THE  PERINEUM.  197 

dent  dissect  off  the  integument  carefully  from  the  whole  of  the  included 

space,  and  he  will  expose  the  fatty  cellular  structure  of  the  common 
superficial  fascia,  which  exactly  resembles  the  superficial  fascia  in 
every  other  situation.  The  common  superficial  fascia  is  then  to  be 
removed  to  the  same  extent,  exposing  the  superficial  perineal  fascia. 
This  layer  is  also  to  be  turned  aside,  when  the  muscles  of  the  genital 
region  of  the  perineum  will  be  brought  into  view. 

The  Accehratores  urincB  arise  from  a  tendinous  point  in  the  centre 
of  the  perineum  and  from  the  raphe.  From  these  origins  the  fibres 
diverge,  like  the  plumes  of  a  pen ;  the  posterior  fibres  to  be  inserted 
into  the  ramus  of  the  pubis  and  ischium ;  the  middle  to  encircle  the 
corpus  spongiosum,  and  meet  upon  its  upper  side ;  and  the  anterior 
to  spread  out  upon  the  corpus  cavernosum  on  each  side,  and  be 
inserted,  partly  into  its  fibrous  structure,  and  partly  into  the  fascia 
of  the  penis.  The  posterior  and  middle  insertions  of  these  muscles 
are  best  seen,  by  carefully  raising  one  muscle  from  the  corpus  spon- 
giosum and  tracing  its  fibres. 

Relations. — By  their  superficial  surface  with  the  superficial  peri- 
neal fascia,  the  dartos,  the  superficial  vessels  and  nerves  of  the  peri- 
neum, and  on  each  side  with  the  erector  penis.  By  their  deep  sur- 
face with  the  corpus  spongiosum  and  bulb  of  the  urethra. 

The  Erector  penis  arises  from  the  ramus  and  tuberosity  of  the 
ischium,  and  curves  around  the  root  of  the  penis,  to  be  inserted  into 
the  upper  surface  of  the  corpus  cavernosum,  where  it  is  continuous 
with  a  strong  fascia  which  covers  the  dorsum  of  the  organ,  the 
fascia  penis. 

Relations. — By  its  superficial  surface  with  the  superficial  perineal 
fascia,  the  dartos,  and  the  superficial  perineal  vessels  and  nerve.  By 
its  deep  surface  with  the  corpus  cavernosum  penis. 

The  Transversus  perinei  arises  from  the  tuberosity  of  the  ischium 
on  each  side,  and  is  inserted  into  the  central  tendinous  point  of  the 
perineum.* 

Relations. — By  its  superficial  surface  with  the  superficial  perineal 
fascia,  and  superficial  perineal  artery.  By  its  deep  surface  with 
the  deep  perineal  fascia,  and  internal  pudic  artery  and  veins.  By  its 
posterior  border  it  is  in  relation  with  that  portion  of  the  superficial 
perineal  fascia  which  passes  back  to  become  continuous  with  the 
deep  fascia. 

To  dissect  the  compressor  urethra',  the  whole  of  the  preceding 
muscles  should  be  removed,  so  as  to  render  the  glistening  surface 
of  the  deep  perineal  fascia  quite  apparent.  The  anterior  layer  of 
this  fascia  should  then  be  carefully  dissected  away,  and  the  corpus 
spongiosum  penis  divided  through  its  middle,  separated  from  the 

*  I  once  dissected  a  perineum  in  which  the  transversus  perinei  was  of  large  size,  and 
spread  out  as  it  approached  the  middle  line  so  as  to  become  fan-shaped.  The  posterior 
fibres  were  continuous  witli  those  of  the  muscle  of  the  opposite  side  ;  but  the  anterior 
were  continued  forwards  upon  the  bulb  and  corpus  spong-iosuni  of  the  uretln-a  as  far  as 
the  middle  of  the  penis,  forming  a  broad  layer  wliich  usurped  the  place  and  office  of  tlie 
accelerator  urinae. 


198 


MUSCLES  OF  THE  PERINEUM. 


corpus  cavernosum,  and  drawn  forwards,  to  put  the  membranous 
portion  of  the  urethra,  upon  which  the  muscle  is  spread  out,  upon 
the  stretch.  The  muscle  is,  however,  better  seen  in  a  dissection 
made  from  within  the  pelvis,  after  having  turned  down  the  bladder 
from  its  attachment  to  the  os  pubis,  and  removed  a  plexus  of  veins 
and  the  posterior  layer  of  the  deep  perineal  fascia. 

Fiff.  81.* 


The  Compressor  urethrcB  (Wilson's  and  Guthrie's  muscles),  con- 
sists of  two  portions ;  one  of  which  is  transverse  in  its  direction,  and 
passes  inwards,  to  embrace  the  membranous  urethra ;  the  other  is 
perpendicular,  and  descends  from  the  pubis.  The  transverse  portion, 
particularly  described  by  Mr.  Guthrie,  arises  by  a  narrow  tendinous 
point,  from  the  upper  part  of  the  ramus  of  the  ischium,  on  each 
side,  and  divides  into  two  fasciculi,  which  pass  inwards  and  slightly 
upwards,  and  embrace  the  membranous  portion  of  the  urethra  and 
Cowper's  glands.  As  they  pass  towards  the  urethra,  they  spread 
out  and  become  fan-shaped,  and  are  inserted  into  a  tendinous  raph^ 
upon  the  upper  and  lower  surfaces  of  the  urethra,  extending  from 
the  apex  of  the  prostate  gland,  to  which  they  are  attached  poste- 
riorly, to  the  bulbous  portion  of  the  urethra,  with  which  they  are 
connected  in  front.  When  seen  from  above,  these  portions  resemble 
two  fans,  connected  by  their  expanded  border  along  the  middle  line 
of  the  membranous  urethra,  from  the  prostate  to  the  bulbous  portion 
of  the  urethra.  The  same  appearance  is  obtained  by  viewing  them 
from  below. 

*  The  muscles  of  the  perineum.  1.  The  accelcratores  urinae  muscles:  the  figure 
rests  upon  the  corpus  spongiosum  penis.  2.  7'he  corpus  cavernosum  of  one  side.  3. 
The  erector  penis  of  one  side.  4.  The  transversus  perinci  of  one  side.  5.  The  trian- 
gular space  through  which  the  deep  perineal  fascia  is  seen.  G.  The  sphincter  ani;  its 
anierior  extremity  is  cut  off.  7.  The  levator  ani  of  the  left  side  ;  tlic  deep  space  be- 
tween the  tuberosity  of  the  ischium  (8)  and  the  anus,  is  the  ischio-rectal  fossa ;  the  same 
fossa  is  seen  upon  the  opposite  side.  9.  The  spine  of  the  ischium.  10.  The  left  coccy- 
geus  muscle.     The  boundaries  of  the  perineum  tire  well  soon  in  this  engraving. 


SPHINCTER  ANI LEVATOR  ANI.  199 

The  perpendicular  portion*  described  by  Mr.  Wilson,  mises  by 
two  tendinous  points  from  the  inner  surface  of  the  arch  of  the  pubis, 
on  each  side  of,  and  close  to  the  symphysi.s.  The  tendinous  origins 
soon  become  muscular,  and  descend  perpendicularly,  to  be  inserted 
into  the  upper  fasciculus  of  the  transverse  portion  of  the  muscle ;  so 
that  it  is  not  a  distinct  muscle  surrounding  the  membranous  portion 
of  the  urethra,  and  supporting  it  as  in  a  shng,  as  described  by  Mr. 
Wilson,  but  merely  an  upper  origin  of  the  transverse  muscle. 

The  compressor  urethree  may  be  considered  either  as  two  sym- 
metrical muscles  meeting  at  the  raphe,  or  as  a  single  muscle:  I  have 
adopted  the  latter  course  in  the  above  description,  as  appearing  to 
me  the  more  consistent  with  the  general  connexions  of  the  muscle, 
and  with  its  actions. 

The  Sphincter  ani  is  a  thin  and  elliptical  plane  of  muscle  closely 
adherent  to  the  integument,  and  surrounding  the  opening  of  the 
anus.  It  arises  posteriorly  in  the  superficial  fascia  around  the 
coccyx,  and  by  a  fibrous  raphe  from  the  apex  of  that  bone ;  and  is 
inserted  anteriorly  into  the  tendinous  centre  of  the  perineum,  and 
into  the  raphe  of  the  integument,  nearly  as  far  forwards  as  the  com- 
mencement of  the  scrotum. 

Relations. — By  its  superficial  surface  with  the  integument.  By 
its  deep  surface  with  the  internal  sphincter,  the  levator  ani,  the  cel- 
lular tissue  and  fat  in  the  ischio-rectal  fossa,  and  in  front  with  the 
superficial  perineal  fascia. 

The  Sphincter  ani  internus  is  a  muscular  ring  embracing  the 
extremity  of  the  intestine,  and  formed  by  an  aggregation  of  the  cir- 
cular muscular  fibres  of  the  rectum. 

Part  of  the  levator  ani  may  be  seen  during  the  dissection  of  the 
anal  portion  of  the  perineum  by  removing  the  fat  which  surrounds 
the  termination  of  the  rectum  in  the  ischio-rectal  fossa.  But  to  study 
the  entire  muscle,  a  lateral  section  of  the  pelvis  must  be  made  by 
sawing  through  the  pubis  a  little  to  one  side  of  the  symphysis,  sepa- 
rating the  bones  behind  at  the  sacro-iliac  symphysis,  and  turning 
down  the  bladder  and  rectum.  The  pelvic  fascia  is  then  to  be  care- 
fully raised,  beginning  at  the  base  of  the  bladder  and  proceeding 
upwards,  until  the  whole  extent  of  the  muscle  be  exposed. 

The  Levator  ani  is  a  thin  plane  of  muscular  fibres,  situated  on 
each  side  of  the  pelvis.  It  arises  from  the  inner  surface  of  the  os 
pubis,  from  the  spine  of  the  ischium,  and  between  those  points  from 
the  angle  of  division  between  the  obturator  and  the  pelvic  fascia. 
Its  fibres  descend  to  be  inserted  into  the  extremity  of  the  coccyx 
into  a  fibrous  raphe  in  front  of  that  bone,  into  the  lower  part  of  the 
rectum,  base  of  the  bladder,  and  prostate  gland. 

*  Mr.  Tyrrell,  who  has  made  many  careful  dissections  of  the  muscles  of  the  perineum, 
has  not  observed  this  portion  of  the  muscle  ;  he  considers  Wilson's  muscle  (with  some 
other  anatomists)  to  be  the  anterior  fibres  of  the  levator  ani,  not  uniting  beneath  the 
urethra  as  described  by  Mr.  Wilson ;  but  inserted  into  a  portion  of  the  pelvic  fascia 
situated  between  the  prostate  gland  and  rectum, — the  recto-vesical  fascia. 


200  3HJSCLES  OF  THE  rERINEUM. 

Izi  the  female  this  muscle  is  inserted  into  the  coccyx  and  fibrous 
raphe,  extremity  of  the  rectum  and  vagina. 

Relations. — By  its  external  or  perineal  surface,  with  a  thin  layer 
of  fascia,  by  which,  and  by  the  obturator  fascia  it  is  separated  from 
the  obturator  internus  muscle ;  with  the  fat  in  the  ischio-rectal  fossa, 
the  deep  perineal  fascia,  the  levator  ani,  and  posterioi'ly  with  the 
gluteus  maximus.  By  its  internal  or  'pelvic  surface  with  the  pelvic 
fascia,  which  separates  it  from  the  viscera  of  the  pelvis  and  peri- 
toneum. 

The  Coccygeus  muscle  is  a  tendino-muscular  layer  of  a  triangular 
form.  It  arises  from  the  spine  of  the  ischium,  and  is  inserted  into 
the  side  of  the  coccyx  and  lower  part  of  the  sacrum. 

Relations. — By  its  internal  or  pelvic  surface,  with  the  rectum ;  by 
its  external  surface  with  the  lesser  and  greater  sacro-ischiatic  liga- 
ments. 

The  muscles  of  the  perineum  in  the  female  are  the  same  as  in  the 
male,  and  have  received  analogous  names.  They  are  smaller  in 
size,  and  are  modified  to  suit  the  different  form  of  the  organs ;  they 
are — 

Constrictor  vaginae, 
Erector  clitoridis, 
Transversus  perinei. 
Compressor  urethrae, 
Sphincter  ani. 
Levator  ani, 
Coccygeus. 

The  Constrictor  vagince  is  analogous  to  the  acceleratores  urinae ; 
it  is  continuous  posteriorly  with  the  sphincter  ani,  interlacing  with 
its  fibres,  and  is  inserted  anteriorly  into  the  sides  of  the  corpora 
cavernosa,  and  fascia  of  the  clitoris. 

The  Transversus  perinei  is  inserted  into  the  side  of  the  constrictor 
vaginee,  and  the  levator  ani  into  the  side  of  the  vagina. 

The  other  muscles  are  precisely  similar  in  their  attachments  to 
those  in  the  male. 

Actions. — The  acceleratores  urinae  being  continuous  at  the  middle 
line,  and  attached  on  each  side  to  the  bone,  by  means  of  their  pos- 
terior fibres  will  support  the  bulbous  portion  of  the  urethra,  and  act- 
ing suddenly  will  propel  the  semen,  or  the  last  drops  of  urine  from 
the  canal.  The  posterior  and  middle  fibres,  according  to  Ki'ause,* 
contribute  towards  the  erection  of  the  corpus  spongiosum,  by  pro- 
ducing compression  upon  the  venous  structure  of  the  bulb ;  and  the 
anterior  fibres,  according  to  Tyrrcll,f  assist  in  the  erection  of  the 
entire  organ  by  compressing  the  vena  dorsalis,  by  means  of  their 
insertion  into  the  fascia  penis.     The  erector  penis  becomes  entitled 

*  Mcillor,  Arcliiv  f'lir  Aaulomic,  Phyyiolojric,  &-c,  1837. 
t  riUcUiroH  in  tlic  College  of  Surgeons.     1839. 


MUSCLES  OF  THE  UPPER  EXTREMITY.  201 

to  its  name  from  spreading  out  upon  the  dorsum  of  the  organ,  into  a 
membranous  expansion  (fascia  penis),  which,  according  to  Krause, 
compresses  the  dorsal  vein  during  the  action  of  the  muscle,  and 
especially  after  the  erection  of  the  organ  has  commenced.  The 
transverse  muscles  serve  to  steady  the  tendinous  centre,  that  the 
muscles  attached  to  it  may  obtain  a  firm  point  of  support.  Accord- 
ing to  Cruveilhier,  they  draw  the  anus  backwards  during  the  expul- 
sion of  the  fgeces,  and  antagonise  the  levatores  ani  which  carry  the 
anus  forwards.  The  compressor  urethrae,  taking  its  fixed  point  from 
the  ramus  of  the  ischium  at  each  side,  can,  says  Mr.  Guthrie,  "  com- 
press the  urethra  so  as  to  close  it ;  I  conceive,  completely  after  the 
manner  of  a  sphincter."  The  transverse  portion  will  also  have  a 
tendency  to  draw  the  urethra  downwards,  whilst  the  perpendicular 
portion  will  draw  it  upwards  towards  the  os  pubis.  The  inferior 
fasciculus  of  the  transverse  muscle,  enclosing  Cowper's  glands,  will 
assist  those  bodies  in  evacuating  their  secretion.  The  external 
sphincter  being  a  cutaneous  muscle  contracts  the  integument  around 
the  anus,  and  by  its  attachment  to  the  tendinous  centre,  and  to  the 
point  of  the  coccyx,  assists  the  levator  ani  in  giving  support  to  the 
opening  during  expulsive  efforts.  The  internal  sphincter  contracts 
the  extremity  of  the  cylinder  of  the  intestine.  The  use  of  the  levator 
ani  is  expressed  in  its  name.  It  is  the  antagonist  of  the  diaphragm 
and  the  rest  of  the  expulsory  muscles,  and  serves  to  support  the 
rectum  and  vagina  during  their  expulsive  eiforts.  The  levator  ani 
acts  in  unison  with  the  diaphragm,  and  rises  and  falls  hke  that  mus- 
cle in  forcible  respiration.  Yielding  to  the  propulsive  action  of  the 
abdominal  muscles,  it  enables  the  outlet  of  the  pelvis  to  bear  a  greater 
force  than  a  resisting  structure,  and  on  the  remission  of  such  actions 
it  restores  the  perineum  to  its  original  form.  The  coccygei  muscles 
restore  the  coccyx  to  its  natural  position,  after  it  has  been  pressed 
backwards  during  defascation  or  during  parturition. 

MUSCLES  OF  THE  UPPER  EXTREMITY. 

The  muscles  of  the  upper  extremity  may  be  arranged  into  groups 
corresponding  with  the  different  regions  of  the  hmb  thus: — 

Anterior  thoracic  region.  Lateral  thoracic  region. 

Pectoralis  major,  Serratus  magnus. 

Pectoralis  minor, 
Subclavius. 

Anterior  scapular  region.  Posterior  scapular  region. 

Subscapularis.  Supra-spinatus, 

Infra-spinatus. 
Teres  minor, 
Teres  major. 

Acromial  region. 

Deltoid. 
26 


202  MUSCLES  OP  THE  UPPER  EXTREMITY. 

Anterior  humeral  region.  Posterior  humeral  region. 

Coraco-brachialis,  Triceps. 

Biceps, 
Brachialis  anticus. 

Anterior  brachial  region.  Posterior  brachial  region. 

Superficial  layer.  Superficial  layer. 

Pronator  radii  teres,  Supinator  longus. 

Flexor  carpi  radialis,  Extensor  carpi  radialis  longior, 

Palmaris  longus.  Extensor  carpi  radialis  brevior, 

Flexor  sublimis  digitorum,  Extensor  communis  digitorum. 

Flexor  carpi  ulnaris.  Extensor  minimi  digiti, 

Extensor  carpi  ulnaris, 
Anconeus. 

Deep  layer.  Deep  layer. 

Flexor  profundus  digitorum.  Supinator  brevis, 

Flexor  longus  pollicis,  Extensor  ossis  metacarpi  pollicis. 

Pronator  quadratus.  Extensor  primi  internodii  pollicis, 

Extensor  secundi  internodii  pol- 
licis, 
Extensor  indicis. 

Hand. 

Radial  region.  Ulnar  region. 

Abductor  pollicis,  Palmaris  brevis, 

Flexor  ossis  metacarpi  (opponens).  Abductor  minimi  digiti. 
Flexor  brevis  pollicis.  Flexor  brevis  minimi  digiti. 

Adductor  pollicis.  Adductor  minimi  digiti. 

Palmar  region. 
Lumbricales, 
Interossei  palmares, 
Interossei  dorsales. 


Anterior  thoracic  region. 
Pectoralis  major, 
Pectoralis  minor, 
Subclavius. 

Dissection. — Make  an  incision  along  the  line  of  the  clavicle,  from 
the  upper  part  of  the  sternum  to  the  acromion  process ;  a  second 
along  the  lower  border  of  the  great  pectoral  muscle,  from  the  lower 
end  of  the  sternum  to  the  insertion  of  its  tendon  into  the  humerus ; 
and  connect  the  two  by  a  third,  carried  longitudinally  along  the 
middle  of  the  sternum.  The  integument  and  superficial  fascia  are 
to  be  dissected  together  from  off  the  fibres  of  the  muscle,  and  always 


PECTORALIS  MAJOR  AND  MINOK.  203 

in  the  direction  of  their  course.  For  this  purpose  the  dissector,  if 
he  have  the  right  arm,  will  commence  with  the  lower  angle  of  the 
flap  ;  if  the  left,  with  the  upper  angle.  He  will  thus  expose  the  pec- 
toralis  major  muscle  in  its  whole  extent. 

The  Pextoralis  major  muscle  arises  from  the  sternal  two-thirds  of 
the  clavicle,  from  one  half  the  breadth  of  the  sternum  its  whole  length, 
and  from  the  cartilages  of  all  the  true  ribs,  excepting  the  first.  It 
is  inserted  by  a  broad  tendon  into  the  anterior  bicipital  ridge  of  the 
humerus. 

That  portion  of  the  muscle  which  arises  from  the  clavicle,  is  sepa- 
rated from  that  connected  with  the  sternum  by  a  distinct  cellular 
interspace;  hence  we  speak  of  the  clavicular  portion  and  sternal  por- 
tion of  the  pectoralis  major.  The  fibres  from  this  very  extensive 
origin  converge  towards  a  narrow  insertion,  giving  the  muscle  a 
radiated  appearance.  But  there  is  a  pecuharity  about  the  forma- 
tion of  its  tendon  which  must  be  carefully  noted.  The  whole  of  the 
lower  border  is  folded  inwards  upon  the  upper  portion,  so  that  the 
tendon  is  doubled  upon  itself  Another  peculiarity  results  from  this 
arrangement:  the  fibres  of  the  upper  portion  of  the  muscle  are  in- 
serted into  the  lower  part  of  the  ridge ;  and  those  of  the  lower  por- 
tion, into  the  upper  part. 

Relations. — By  its  external  surface  with  the  fibres  of  origin  of  the 
platysma  myoides,  the  mammary  gland,  the  superficial  fascia  and 
integument.  By  its  internal  surface,  on  the  thorax,  with  the  clavicle, 
the  sternum,  the  costal  cartilages,  intercostal  muscles,  subclavius, 
pectoraUs  minor,  and  serratus  magnus  ;  in  the  axilla,  with  the  axil- 
lary vessels  and  glands.  By  its  external  border  with  the  deltoid, 
from  which  it  is  separated  by  a  cellular  interspace  lodging  the 
cephalic  vein  and  the  descending  branch  of  the  thoracico-acromialis 
artery.  Its  lower  border  forms  the  anterior  boundary  of  the  axillary 
space. 

The  pectoralis  major  is  now  to  be  removed  by  dividing  its  fibres 
along  the  lower  border  of  the  clavicle,  and  then  carrying  the  inci- 
sion perpendicularly  downwards,  parallel  to  the  sternum,  and  at 
about  three  inches  from  its  border.  Divide  some  loose  cellular 
tissue,  and  several  small  branches  of  the  thoracic  arteries,  and  re- 
flect the  muscle  outwards.  We  thus  bring  into  view  a  region  of 
considerable  interest,  in  the  middle  of  which  is  situated  the  pectoralis 
minor. 

The  Pectoralis  minor  arises  by  three  digitations  from  the  third, 
fourth,  and  fifth  ribs,  and  is  inserted  into  the  anterior  border  of  the 
coracoid  process  of  the  scapula  by  a  broad  tendon. 

Relations. — By  its  anterior  surface  with  the  pectoralis  major  and 
superior  thoracic  vessels  and  nerves.  By  its  posterior  surface  with 
the  ribs,  the  intercostal  muscles,  serratus  magnus,  axillary  space, 
and  axillary  vessels  and  nerves.  Its  ufper  border  forms  the  lower 
boundary  of  a  triangular  space  bounded  above  by  the  costo-coracoid 
membrane,  and  internally  by  the  ribs.     In  this  space  are  found  the 


204  '  LATERAL  THORACIC  REGION. 

axillary  vessels  and  nerves,  and  in  it  the  subclavian  artery  is  tied 
below  the  clavicle. 

The  Suhdavius  muscle  arises  by  a  round  tendon  from  the  cartilage 
of  the  first  rib,  and  is  inserted  into  the  under  surface  of  the  clavicle. 
This  muscle  is  concealed  by  the  costo-coracoid  membrane,  an  ex- 
tension of  the  deep  cervical  fascia,  by  which  it  is  invested. 

Relations. — By  its  upper  surface  with  the  clavicle.  By  the  lower 
with  the  subclavian  artery  and  vein,  and  brachial  plexus,  which 
separate  it  from  the  first  rib.  In  front  with  the  pectoralis  major, 
the  costo-coracoid  membrane  being  interposed. 

Actions. — The  pectoralis  major  draws  the  arm  against  the  thorax, 
while  its  upper  fibres  assist  the  upper  part  of  the  trapezius  in  raising 
the  shoulder,  as  in  supporting  weights.  The  lower  fibres  depress 
the  shoulder  with  the  aid  of  the  latissimus  dorsi.  Taking  its  fixed 
point  from  the  shoulder,  the  pectoralis  major  assists  the  pectoralis 
minor,  subclavius,  and  serratus  magnus,  in  drawing  up  and  expand- 
ing the  chest.  The  pectoraUs  minor,  in  addition  to  this  action, 
draws  upon  the  coracoid  process,  and  assists  in  rotating  the  scapula 
upon  the  chest.  The  subclavius  draws  the  clavicle  downwards  and 
forwards,  and  thereby  assists  in  steadying  the  shoulder.  All  the 
muscles  of  this  group  are  agents  in  forced  respiration,  but  are  unable 
to  act  until  the  shoulders  be  fixed. 

Lateral  thoracic  Region. 
Serratus  magnus. 

The  Serratus  magnus  (serratus,  indented  like  the  edge  of  a  saw,) 
arises  by  fleshy  serrations  from  the  nine  upper  ribs  excepting  the 
first,  and  extends  backwards  upon  the  side  of  the  chest,  to  be  inserted 
into  the  whole  length  of  the  base  of  the  scapiila.  It  indigitates  by 
means  of  its  five  lower  serrations  with  the  obliquus  externus  abdo- 
minis. 

Relations. — By  its  superficial  surface  with  the  pectoralis  major 
and  minor,  the  subscapularis,  and  the  axillary  vessels  and  nerves. 
By  its  deep  surface  with  the  ribs  and  intercostal  muscles,  to  which 
it  is  connected  by  an  extremely  loose  celhilar  tissue. 

Actions. — The  serratus  magnus  is  the  great  external  inspiratory 
muscle,  raising  the  ribs  when  the  shoulders  are  fixed,  and  thereby 
increasing  the  cavity  of  the  chest.  Acting  upon  the  scapula,  it 
draws  the  shoulder  forwards,  as  we  see  to  be  the  case  in  diseased 
lungs,  where  the  chest  has  become  almost  fixed  from  apprehension 
of  the  expanding  action  of  the  respiratory  muscles. 

Anterior  scapular  Region. 
Subscapularis. 

The  Subscapularis  muscle  arises  from  the  whole  of  the  under 
surface  of  the  scapula  excepting  the  superior  angle,  and  terminates 
by  a  broad  and  thick  tendon,  wliicli  is  inserted  into  the  lesser  tube- 


PECTORALIS  MAJOR  AND  MINOR.  205 

rosity  of  the  humerus.  The  tendon  of  this  muscle  forms  a  part  of 
the  capsule  of  the  joint,  glides  over  a  large  bursa  which  separates 
it  from  the  base  of  the  coracoid  process,  and  is  lined  by  a  prolonga- 
tion of  the  synovial  membrane  of  the  articulation. 

Relations. — By  its  anterior  surface  with  the  serratys  magnus,  the 
coraco-brachialis,  deltoid,  and  with  the  axillary  vessels  and  nerves. 
By  its  posterior  surface  with  the  scapula,  the  subscapular  vessels 
and  nerves,  and  the  shoulder  joint. 

Action. — It  rotates  the  head  of  the  humerus  inwards,  and  is  a 
powerful  defence  to  the  joint.  When  the  arm  is  raised,  it  draws 
the  humerus  downwards. 

Posterior  scapular  Region. 
Supra-spinatus,  Teres  minor, 

Infra-spinatus,  Teres  major. 

The  Supra-spinatus  muscle,  {supra,  above;  spina,  the  spine)  arises 
from  the  whole  of  the  supra-spinous  fossa,  and  is  inserted  into  the 
uppermost  depression  on  the  great  tuberosity  of  the  humerus.  The 
tendon  of  this  muscle  cannot  be  well  seen  without  cutting  away  the 
acromion  process  with  a  saw. 

Relations. — By  its  upper  surface  with  the  trapezius,  the  clavicle, 
acromion,  and  coraco-acromial  ligament.  From  the  trapezius  it  is 
separated  by  a  strong  fascia.  By  its  lower  surface  with  the  supra- 
spinous fossa,  the  supra-scapular  vessels  and  nerve,  and  the  upper 
part  of  the  shoulder  joint,  forming  part  of  the  capsular  ligament. 

The  Infraspinatus  {infra,  beneath ;  spina,  the  spine,)  is  covered 
in  by  a  layer  of  tendinous  fascia,  which  must  be  removed  before  the 
fibres  of  the  muscle  can  be  seen,  the  deltoid  muscle  having  been 
previously  turned  down  from  its  scapular  origin.  It  arises  from  the 
whole  of  the  infra-spinous  fossa,  and  from  the  fascia  above-mentioned, 
and  is  inserted  into  the  middle  depression  upon  the  greater  tuberosity 
of  the  humerus. 

Relations. — By  its  posterior  surface  with  the  deltoid,  latissimus 
dorsi  and  integument.  By  its  anterior  surface  with  the  infra-spinous 
fossa,  superior  and  dorsal  scapular  vessels,  and  shoulder  joint ;  its 
tendon  being  lined  by  a  prolongation  from  the  synovial  membrane. 
By  its  upper  border  it  is  in  relation  with  the  spine  of  the  scapula, 
and  by  the  lower  with  the  teres  minor,  with  which  it  is  closely 
united. 

The  Teres  minor  muscle  {teres,  round)  arises  from  the  middle 
third  of  the  inferior  border  of  the  scapula,  and  is  inserted  into  the 
lower  depression  on  the  great  tuberosity  of  the  humerus.  The  ten- 
dons of  these  three  muscles,  with  that  of  the  subscapularis,  are  in 
immediate  contact  with  the  joint,  and  form  part  of  its  ligamentous 
capsule,  thereby  preserving  the  solidity  of  the  articulation.  They 
are  therefore  the  structures  most  frequently  ruptured  in  dislocation 
of  the  shoulder-joint  with  violence. 

Relations. — By  its  posterior  surface  with  the  deltoid,  latissimus 
dorsi  and  integument.     By  its  anterior  surface  with  the  inferior  bor- 


206  ACROMIAL  REGION DELTOID, 

der,  and  part  of  the  dorsum  of  the  scapula,  the  dorsalis  scapulae  ves- 
sels, scapular  head  of  the  triceps,  and  shoulder  joint.  By  its  upper 
border  with  the  infra-spinatus ;  and  by  the  loiver  with  the  latissimus 
dorsi,  teres  major,  and  long  head  of  the  triceps. 

The  Teres  major  muscle  arises  from  the  lower  third  of  the  inferior 
border  of  the  scapula,  encroaching  a  little  upon  its  dorsal  aspect,  and 
is  inserted  into  the  posterior  bicipital  ridge.  Its  tendon  lies  imme- 
diately behind  that  of  the  latissimus  dorsi,  from  which  it  is  separated 
by  a  synovial  membrane. 

Relations. — By  its  posterior  surface  with  the  latissimus  dorsi,  sca- 
pular head  of  the  triceps  and  integument.  By  its  anterior  surface 
with  the  subscapularis,  latissimus  dorsi,  coraco-brachialis,  short  head 
of  the  biceps,  axillary  vessels,  and  branches  of  the  brachial  plexus. 
By  its  upper  border  it  is  in  relation  with  teres  minor,  from  which 
it  is  separated  by  the  scapular  head  of  the  triceps,  and  by  the  lower 
it  forms  with  the  latissimus  dorsi  the  lower  and  posterior  border  of 
the  axilla. 

A  large  triangular  space  exists  between  the  two  teres  muscles, 
which  is  divided  into  two  minor  spaces  by  the  long  head  of  the 
triceps. 

Actions. — The  supra-spinatus  raises  the  arm  from  the  side ;  but 
only  feebly,  from  the  disadvantageous  direction  of  its  force.  The 
infra-spinatus  and  teres  minor  are  rotators  of  the  head  of  the  hume- 
rus outwards.  The  most  important  use  of  these  three  muscles  is  the 
protection  of  the  joint,  and  defence  against  displacement  of  the  head 
of  the  humerus,  in  which  action  they  co-operate  with  the  subscapu- 
laris. The  teres  major  combines,  with  the  latissimus  dorsi,  in  rotating 
the  arm  inwards,  and  at  the  same  time  carrying  it  towards  the  side, 
and  somewhat  backwards. 

Acromial  Region. 

Deltoid. 

The  convexity  of  the  shoulder  is  formed  by  a  large  triangular 
muscle,  the  deltoid  (A,  delta ;  si^o^,  resemblance),  which  arises  from 
the  outer  third  of  the  clavicle,  from  the  acromion  process,  and  from 
the  whole  length  of  the  spine  of  the  scapula.  The  fibres  from  this 
broad  origin  converge  to  the  middle  of  the  outer  side  of  the  humerus, 
where  they  are  inserted  into  a  rough  triangular  elevation.  This 
muscle  is  remarkable  for  its  coarse  texture,  and  the  combination  of 
tendinous  and  muscular  fibres.  The  deltoid  muscle  may  now  be 
cut  away  from  its  origin,  and  turned  down,  for  the  purpose  of  bring- 
ing into  view  the  muscles  and  tendons  placed  immediately  around 
the  shoulder  joint.  In  so  doing,  a  large  bursa  will  be  seen  between 
the  under  surface  of  the  muscle  and  the  head  of  the  humerus. 

Relations. — By  its  superficial  surface  with  a  thin  aponeurotic 
fascia,  a  few  fibres  of  the  platysma  myoides,  the  superficial  fascia 
and  integument.  By  its  deep  surface  with  the  shoulder  joint,  from 
which  it  is  separated  by  a  thin  tendinous  fascia,  and  by  a  synovial 
bursa ;  with  the  coraco-acromial  ligament,  coracoid  process,  pecto- 
ralis  minor,  coraco-brachialis,  both  heads  of  the  biceps,  tendon  of 


ANTERIOR  HUMERAL  REGION. 


207 


the  pectoralis  major,  tendon  of  the  supra-spinatus,  infra-spinatus, 
teres  minor,  teres  major,  scapular  and  external  head  of  the  triceps, 
the  circumflex  vessels  anterior  and  posterior,  and  humerus.  By  its 
anterior  border  with  the  external  border  of  the  pectorahs  _  major, 
from  which  it  is  separated  by  a  cellular  interspace,  lodging  the 
cephalic  vein  and  descending  branch  of  the  thoracico-acromialis 
artery.  Its  posterior  border  is  thin  above,  where  it  is  connected  with 
the  aponeurotic  covering  of  the  infra-spinatus  muscle,  and  thickbelow. 
Actions.-— The  deltoid  is  the  elevator  muscle  of  the  arm  in  a  direct 
line,  and  by  means  of  its  extensive  origin  can  carry  the  arm  forwards 
or  backwards  so  as  to  range  with  the  hand  a  considerable  segment 
of  a  large  circle.  The  arm,  raised  by  the  deltoid,  is  a  good  illus- 
tration of  a  lever  of  the  third  power,  so  common  in  the  animal  ma- 
chine, by  which  velocity  is  gained  at  the  expense  of  power.  In  this 
lever,  the  weight  (hand)  is  at  one  extremity,  the  fulcrum  (the  glenoid 
cavity)  at  the  opposite  end,  and  the  power  (the  insertion  of  the  mus- 
cle) between  the  two,  but  nearer  to  the  fulcrum  than  to  the  weight. 

Anterior  Humeral  Region. 

Coraco-brachialis, 

Biceps, 

Brachialis  anticus. 
Dissection. — These  muscles  are  exposed,  Fig-  82.* 

on  the  removal  of  the  integument  and  fascia 
from  the  anterior  half  of  the  upper  arm,  and 
clearing  away  the  cellular  tissue. 

The  Coraco-brachialis,  a  name  composed 
of  its  points  of  origin  and  insertion,  arises 
from  the  coracoid  process  in  common  with 
the  short  head  of  the  biceps;  and  is  inserted 
into  a  rough  line  on  the  inner  side  of  the 
middle  of  the  humerus. 

Relations. — By  its  anterior  surface  with 
the  deltoid,  and  pectoralis  major.  By  its 
posterior  surface  with  the  shoulder  joint,  the 
humerus,  subscapularis,  teres  major,  latissi- 
mus  dorsi,  short  head  of  the  triceps,  and  an- 
terior circumflex  vessels.  By  its  internal 
border  with  the  axillary  and  brachial  vessels 
and  nerves,  particularly  with  the  median  and 
external  cutaneous  nerve,  by  the  latter  of 
which  it  is  pierced.  By  the  external  border 
with  the  short  head  of  the  biceps  and  bra- 
chialis anticus. 

The  Biceps  (bis — ^s(pakai,  two  heads)  arises 

*  The  muscles  of  the  anterior  aspect  of  the  upper  arm.  1.  The  coracoid  process  of 
the  scapula.  2.  The  coraco-clavicular  ligament  (trapezoid),  passing  upwards  to  the 
scapular  end  of  the  clavicle.  8.  The  coraco-acromial  ligament,  passing  outwards  to  tlie 
acromion.  4.  The  subscapularis  nmscle.  5.  The  teres  major.  6.  Tlie  coraco-bra- 
chialis. 7.  The  biceps.  8.  The  upper  end  of  the  radius.  9.  The  brachialis  anticus, 
10.  The  internal  head  of  the  triceps. 


208  POSTERIOR  HUMERAL  REGION. 

by  two  tendons,  one  the  short  head,  from  the  coracoid  process  in 
common  with  the  coraco-bracliiahs ;  the  other  the  Io7ig  head,  from 
the  upper  part  of  the  glenoid  cavity.  The  muscle  is  inserted  by  a 
rounded  tendon,  into  the  tubercle  of  the  radius.  The  long  head,  a 
long  slender  tendon,  passes  through  the  capsular  ligament  of  the 
shoulder  joint  enclosed  in  a  sheath  of  the  synovial  membrane  ;  after 
leaving  the  cavity  of  the  joint,  it  is  lodged  in  the  deep  groove  that 
separates  the  two  tuberosities  of  the  humerus,  the  bicipital  groove. 
A  small  synovial  bursa  is  interposed  between  the  tendon  of  inser- 
tion, and  the  tubercle  of  the  radius.  M  the  hend  of  the  elbow,  the 
tendon  of  the  biceps  gives  off  from  its  inner  side  a  broad  tendinous 
band,  which  protects  the  brachial  artery,  and  is  continuous  with  the 
fascia  of  the  fore-arm. 

Relations. — By  its  anterior  surface  with  the  deltoid,  pectoraUs 
major,  superficial  and  deep  fascia  and  integument.  By  its  posterior 
surface  the  short  head  rests  upon  the  subscapularis,  from  which  it  is 
separated  by  a  bursa.  In  the  rest  of  its  extent  the  muscle  is  in  rela- 
tion with  the  humerus,  the  teres  major,  latissimus  dorsi,  and  brachi- 
alis  anticus,  from  which  it  is  separated  by  the  external  cutaneous 
nerve.  By  its  inner  border  with  the  coraco-brachialis,  brachial 
artery  and  veins,  and  median  nerve ;  the  brachial  vessels  crossing  its 
tendon  at  the  bend  of  the  elbow.  By  its  outer  border  with  the  del- 
toid and  supinator  longus. 

The  BrachiaUs  anticus  is  a  broad  muscle  covering  the  whole  of 
the  anterior  surface  of  the  lower  part  of  the  humerus ;  it  arises  by 
two  fleshy  serrations  from  the  depressions  on  either  side  of  the  inser- 
tion of  the  deltoid,  and  from  the  anterior  surface  of  the  humerus. 
Its  fibres  converge  to  be  inserted  into  the  coracoid  process  of  the 
ulna. 

Relations. — By  its  anterior  surface  with  the  biceps,  external  cuta- 
neous nerve,  brachial  artery  and  veins,  and  median  nerve.  By  its 
'posterior  surface  with  the  humerus,  and  anterior  ligament  of  the 
elbow  joint.  By  its  external  border  With,  the  supinator  longus,  exten- 
sor carpi  radialis  longior,  musculo-spinal  nerve,  and  recurrent  radial 
artery.  By  its  internal  border  with  the  intermuscular  aponeurosis, 
which  separates  it  from  the  triceps  and  ulnar  nerve,  and  with  the 
pronator  radii  teres. 

Actions. — The  coraco-brachialis  draws  the  humerus  inwards,  and 
assists  in  flexing  it  upon  the  scapula.  The  biceps  and  brachialis 
anticus  are  flexors  of  the  fore-arm,  and  the  former  a  supinator.  The 
brachiaUs  anticus  is  a  powerful  protection  to  the  elbow-joint. 

Posterior  Humeral  region. 
Triceps  extensor  cubiti. 

Dissection. — Remove  the  integument  and  fascia  from  the  posterior 
aspect  of  the  upper  arm. 

The  Triceps  (rgsrg  jcscpaXa/,  three  heads,)  arises  by  three  heads. 


POSTERIOR  HUMERAL  REGION. 


209 


Fig.  83.* 


Considered  in  relation  to  their  length,  these  heads  have  been  named 
long,  short,  and  middle ;  and  in  reference  to  their  position,  internal, 
external,  and  middle ;  the  term  middle,  in  the  former  case,  referring 
to  the  external  head,  and  in  the  latter  case  to  the  long  head.  This 
has  given  rise  to  much  confusion  and  misunderstanding.  I  shall, 
therefore,  confine  myself  to  the  designations  derived  from  their  rela- 
tions. The  external  head  arises  from  the  humerus  immediately 
below  the  insertion  of  the  teres  minor.  The  internal  head  (short) 
arises  from  the  humerus  immediately  belovv^  the  insertion  of  the  teres 
major.  The  scapular  head  (long)  lies  be- 
tvi^een  the  two  others,  and  arises  from  the 
upper  third  of  the  inferior  border  of  the  sca- 
pula. The  three  heads  unite  to  form  a  broad 
muscle,  which  is  inserted  by  an  aponeurotic 
tendon  into  the  olecranon  process  of  the 
ulna ;  a  small  bursa  is  situated  between  its 
tendon  and  the  upper  part  of  the  olecranon. 

The  scapular  head  of  the  triceps  passes 
between  the  teres  minor  and  major,  and  di- 
vides the  triangular  space  between  those  two 
muscles  into  two  smaller  spaces,  one  of 
which  is  triangular,  the  other  quadrangular. 
The  triangular  space  is  bounded  by  the  teres 
minor,  teres  major,  and  scapular  head  of  the 
triceps ;  it  gives  passage  to  the  dorsahs  sca- 
pula artery  and  veins.  The  quadrangular 
space  is  bounded  on  three  sides  by  the  three 
preceding  muscles,  and  on  the  fourth  by  the 
humerus.  Through  this  space  pass  the  pos- 
terior circumflex  artery  and  veins,  and  cir- 
cumflex nerve. 

Relations. — By  its  posterior  surface  with 
the  deep  and  superficial  fascia  and  integu- 
ment. By  its  anterior  surface  with  the  supe- 
rior profunda  artery,  musculo-spiral  nerve, 
humerus,  intermuscular  aponeurosis  which 
separates  it  from  the  brachialis  anticus,  and  with  the  elbow-joint. 
The  scapular  head  is  in  relation  posteriorly  with  the  deltoid  and 
teres  minor;  anteriorly  with  the  subscapularis,  teres  major,  and 
latissimus  dorsi ;  and  externally  with  the  posterior  circumflex  ves- 
sels and  nerve. 

Actions, — The  triceps  is  an  extensor  of  the  fore-arm. 


*  A  posterior  view  of  the  upper  arm,  showing-  the  triceps  muscle.  1.  Its  external 
head.  2.  Its  long,  or  scapular  head.  3.  Its  internal,  or  short  head.  4.  The  olecranon 
process  of  the  ulna.     5.  The  radius.     G.  The  capsular  ligament  of  the  shoulder-joint. 

27 


210  ANTERIOR  BRACHIAL  REGION. 

Anteriai'  Brachial  region. 
Superficial  layer. 

Pronator  radii  teres, 
Flexor  carpi  radialis, 
Palmaris  longus, 
Flexor  sublimis  digitorum, 
Flexor  carpi  ulnaris. 

Dissection. — These  muscles  are  seen  by  making  an  incision 
through  the  integument  along  the  middle  line  of  the  fore-arm,  cross- 
ing each  extremity  by  a  transverse  incision,  and  turning  aside  the 
flaps.     The  superficial  and  deep  fascia  are  then  to  be  removed. 

The  Pronator  radii  teres  arises  by  tv^^o  heads ;  one  from  the  inner 
condyle  of  the  humerus,  fascia  of  the  fore-arm  and  intermuscular 
aponeurosis ;  the  other,  from  the  coronoid  process  of  the  ulna ;  the 
median  nerve  passing  between  them.  Its  tendon  is  inserted  into  the 
middle  third  of  the  oblique  ridge  of  the  radius.  The  two  heads  of 
this  muscle  are  best  seen,  by  cutting  away  that  which  arises  from 
the  inner  condyle,  and  turning  it  aside.  The  second  head  will  then 
be  seen  with  the  median  nerve  lying  across  it. 

Relations. — By  its  anterior  surface  with  the  fascia  of  the  fore-arm, 
the  supinator  longus,  extensor  carpi  radialis  longior  and  brevior, 
radial  artery  and  veins,  and  radial  nerve.  By  its  posterior  surface 
with  the  brachialis  anticus,  flexor  sublimis  digitorum,  the  ulnar 
artery  and  veins,  and  the  median  nerve  after  it  has  passed  between 
the  two  heads  of  the  muscle.  By  its  upper  hm^der  it  forms  the  inner 
boundary  of  the  triangular  space,  in  which  the  termination  of  the 
brachial  artery  is  situated.  By  its  lower  border  it  is  in  relation  with 
the  flexor  carpi  radialis. 

The  Flexor  carpi  radialis  arises  from  the  inner  condyle  and  the 
sheath  of  fascia  which  surrounds  it.  Its  tendon  passes  through  a 
groove  formed  by  the  scaphoid  bone  and  trapezium,  to  be  inserted 
into  the  base  of  the  metacarpal  bone  of  the  index  finger. 

Relations. — By  its  anterior  surface  with  the  fascia  of  the  fore-arm, 
and  at  the  wrist  with  the  tendinous  canal  through  which  its  tendon 
passes.  By  its  posterior  surface  with  the  flexor  sublimis  digitorum, 
flexor  longus  pollicis,  wrist-joint,  and  groove  in  the  scaphoid  and 
trapezium  bones.  By  its  outer  border  with  the  pronator  radii  teres, 
and  radial  artery  and  veins.  By  its  inner  border  with  the  palmaris 
longus.  The  tendon  is  surrounded  by  a  synovial  membrane  where 
it  plays  through  the  tendinous  canal  of  the  wrist. 

The  Palmaris  longus  muscle  arises  from  the  inner  condyle,  and 
from  the  sheath  of  fascia  which  surrounds  it.  It  is  inserted  into  the 
palmar  fascia.     Occasionally  this  muscle  is  wanting. 

Relations. — By  its  anterior  surface  with  the  fascia  of  the  fore-arm. 
By  the  posterior  surface  with  the  flexor  sublimis  digitorum;  to  the 
external  side  by  the  flexor  carpi  radialis;  and  to  the  internal  side 
by  the  flexor  carpi  ulnaris. 


PLEXOR  SUBLIMIS  DIGITORUM. 


211 


Cut  the  flexor  carpi  radialis  and  ,  palmaris  longus  from  their 
origins,  in  order  to  obtain  a  good  view  of  the  whole  extent  of  origin 
of  the  flexor  subhmis  disitorum. 


Fig.  84.^ 


Fig.  85.t 


The  Flexor  subiimis  digitorum  (perforatus)  arises  from  the  inner 
condyle,  coronoid  process  of  the  ulna,  and  obhque  hne  of  the  radius. 
The  median  nerve  and  ulnar  artery  pass  between  its  origins.     It 

*  Superficial  layer  of  muscles  of  the  fore-arm.  1.  The  lower  part  of  the  biceps, 
with  its  tendon.  2.  A  part  of  the  bracliialis  anticus,  seen  beneath  the  biceps.  3.  A 
part  of  the  triceps.  4.  The  pronator  radii  teres.  5.  The  flexor  carpi  radialis.  6.  The 
palmaris  longus.  7.  One  of  the  fasciculi  of  the  flexor  subiimis  digitorum  ;  the  rest  of 
the  muscle  is  seen  beneath  the  tendons  of  tlic  palmaris  longus  and  flexor  carpi  radialis. 
8.  The  flexor  carpi  ulnaris.  9.  The  palmar  fascia.  10.  The  palmaris  brevis  muscle. 
11.  The  abductor  pollicis  muscle.  12.  One  portion  of  the  flexor  brevis  pollicis ;  the 
leading  line  crosses  a  part  of  the  adductor  pollicis.  13.  The  supinator  longus  muscle. 
14.  The  extensor  ossis  metacarpi,  and  extensor  primi  internodii  pollicis,  curving  around 
tlie  lower  border  of  the  fore-arm. 

t  The  deep  layer  of  muscles  of  the  fore-arm.  1.  The  internal  lateral  ligament  of 
the  elbow-joint.  2.  The  anterior  ligament.  3.  The  orbicular  ligament  of  the  head  of 
the  radius.  1.  The  flexor  profundus  digitorum  muscle.  5.  The  flexor  longus  pollicis. 
G.  The  pronator  quadratus.  7.  The  adductor  pollicis  muscle.  8.  The  dorsal  interos- 
seous muscle  of  the  middle  finger,  and  palmar  interosseous  of  the  ring-finger.  9.  The 
dorsal  interosseous  muscle  of  the  ring-finger,  and  palmar  interosseous  of  the  little  finger. 


212  FLEXOR  PROFUNDUS  DIGITORUM. 

divides  into  four  tendons,  which  pass  beneath  the  annular  Hgament 
into  the  pahii  of  the  hand,  and  are  inserted  into  the  base  of  the 
second  phalanges  of  the  fingers,  splitting  at  their  terminations  to 
give  passage  to  the  tendons  of  the  deep  flexors ;  thence  its  designa- 
tion 'perforatus. 

Relations. — In  the  fore-arm.  By  its  anterior  surface  with  the 
pronator  radii  teres,  flexor  carpi  radialis,  palmaris  longus,  flexor 
carpi  ulnaris,  and  the  deep  fascia  of  the  fore-arm.  By  its  -posterior 
surface  with  the  flexor  profundus  digitorum,  flexor  longus  pollicis, 
ulnar  artery,  veins,  and  nerve,  and  median  nerve.  This  muscle 
usually  sends  a  fasciculus  to  the  flexor  longus  pollicis.  In  the  hand: 
tts  tendons,  after  passing  beneath  the  annular  ligament,  are  in  rela- 
iion  superficially  with  the  superficial  palmar  arch,  and  palmar  fascia; 
and  deeply  with  the  tendons  of  the  deep  flexor  and  lumbricales. 

The  Flexor  carpi  ulnaris  arises  by  two  heads,  one  from  the  inner 
condyle,  the  other  from  the  olecranon  and  upper  two-thirds  of  the 
inner  border  of  the  ulna.  Its  tendon  is  inserted  into  the  pisiform 
bone,  and  base  of  the  metacai-pal  bone  of  the  little  finger. 

Relations. — By  its  anterior  surface  with  the  fascia  of  the  fore-arm, 
with  which  it  is  closely  united  superiorly.  By  its  posterior  surface 
with  the  flexor  sublimis  digitorum,  flexor  profundus,  pronator  quad- 
ratus,  and  ulnar  artery,  veins,  and  nerve.  By  its  radial  border  with 
the  palmaris  longus,  and  in  the  lower  third  of  the  fore-arm  with  the 
ulnar  vessels  and  nerve.  The  ulnar  nerve,  and  the  posterior  ulnar 
recurrent  artery,  pass  between  its  two  heads  of  origin. 

Deep  layer. 

Flexor  profundus  digitorum, 
Flexor  longus  pollicis, 
Pronator  quadratus. 

Dissection. — This  group  is  brought  into  view  by  removing  the 
flexor  sublimis,  and  drawing  aside  the  pronator  radii  teres. 

Flexor  profundus  digitorum  (perforans)  arises  from  the  upper  two- 
thirds  of  the  ulna  and  part  of  the  interosseous  membrane,  and  termi- 
nates in  four  tendons,  which  pass  beneath  the  annular  ligament,  and 
between  the  two  slips  of  the  tendons  of  the  flexor  sublimis  (hence 
its  designation,  perforans),  to  be  inserted  into  the  base  of  the  last 
phalanges.  The  tendon  of  the  index  finger  is  always  distinct  from 
the  rest,  the  other  three  tendons  being  more  or  less  intimately  con- 
nected by  cellular  tissue  and  tendinous  slips. 

Four  little  muscular  fasciculi,  called  lumbricales,  are  connected 
with  the  tendons  of  this  muscle  in  the  palm.  They  will  be  described 
with  the  muscles  of  the  hand. 

Relations. — In  the  fore-arm.  By  its  anterior  surface  with  the 
flexor  sublimis  digitorum,  flexor  carpi  ulnaris,  median  nerve,  and 
ulnar  artery,  veins,  and  nerve.  By  its  posterior  surface  with  the 
ulna,  the  interosseous  membrane,  the  pronator  quadratus,  and  the 


FLEXOR  LONGUS  POLUCIS PRONATOR  aUADRATUS.  213 

wrist-joint.  By  its  radial  border  with  the  flexor  longus  pollicis,  the 
anterior  interosseous  artery  and  nerve  being  interposed.  By  its 
ulnar  border  with  the  flexor  carpi  ulnaris.  In  the  hand :  its  tendons 
are  in  relation  swperficially  with  the  tendons  of  the  superficial  flexor ; 
and  deeply  with  the  interossei  muscles,  adductor  pollicis,  and  deep 
palmar  arch.  In  the  fingers :  the  tendons  of  the  deep  flexor  are 
interposed  between  the  tendons  of  the  superficial  flexor  and  the 
phalanges. 

The  Flexor  longus  -pollicis  arises  from  the  upper  two-thirds  of  the 
radius,  and  part  of  the  interosseous  membrane.  Its  tendon  passes 
beneath  the  annular  ligament,  to  be  inserted  into  the  base  of  the  last 
phalanx  of  the  thumb. 

Relations. — By  its  anterior  surface  with  the  flexor  sublimis  digito- 
rum,  flexor  carpi  radialis,  supinator  longus,  and  radial  artery  and 
veins.  By  its  posterior  surface  with  the  radius,  interosseous  mem- 
brane, pronator  quadratus  and  wrist-joint.  By  its  idnar  border  it  is 
separated  from  the  flexor  profundus  digitorum  by  the  anterior  inter- 
osseous artery  and  nerve.  In  the  hand :  after  passing  beneath  the 
annular  ligament,  it  is  lodged  in  the  interspace  between  the  two  por- 
tions of  the  flexor  brevis  pollicis,  and  afterwards  in  the  tendinous 
theca  of  the  phalanges. 

If  the  tendons  of  the  two  last  muscles  be  drawn  aside  or  divided, 
the  third  muscle  of  this  group  will  be  brought  into  view,  lying  across 
the  lower  part  of  the  two  bones. 

The  Pronator  quadratus  arises  from  the  ulna,  and  is  inserted  into 
the  lower  fourth  of  the  obhque  hne,  on  the  outer  side  of  the  radius. 
This  muscle  occupies  about  the  lower  fourth  of  the  two  bones,  is 
broad  at  its  origin,  and  narrower  at  its  insertion. 

Relations. — By  its  anterior  surface  with  the  tendons  of  the  supina- 
tor longus,  flexor  carpi  radialis,  flexor  longus  pollicis,  flexor  profun- 
dus digitorum,  and  flexor  carpi  ulnaris,  radial  artery  and  veins,  and 
ulnar  artery,  veins,  and  nerve.  By  its  posterior  surface  with  the 
radius,  ulna,  and  interosseous  membrane. 

Actions. — The  pronator  radii  teres  and  pronator  quadratus  muscles 
rotate  the  radius  upon  the  ulna,  and  render  the  hand  prone.  The 
remaining  muscles  are  flexors: — two  flexors  of  the  wrist,  flexor 
carpi  radialis  and  ulnaris ;  two  of  the  fingers,  flexor  subUmis  and 
profundus,  the  former  flexing  the  second  phalanges,  the  latter  the 
last ;  one  flexor  of  the  last  phalanx  of  the  thumb,  flexor  longus  pol- 
licis.    The  palmaris  longus  is  a  tensor  of  the  palmar  fascia. 

Posterior  brachial  Region. 
Superficial  layer. 
Supinator  longus, 
Extensor  carpi  radiahs  longior, 
Extensor  carpi  radialis  brevier. 
Extensor  communis  digitorum, 
Extensor  minimi  digiti, 
Extensor  carpi  ulnaris. 
Anconeus. 


214  POSTERIOR  BRACHIAL  REGION. 

Dissection. — The  integument  is  to  be  divided  and  turned  aside, 
and  the  fascice  removed  in  the  same  manner  as  for  the  anterior  bra- 
chial region. 

The  Supinator  longus  muscle  is  placed  along  the  radial  border  of 
the  fore-arm.  It  arises  from  the  external  condyloid  ridge  of  the 
humerus,  nearly  as  high  as  the  insertion  of  the  deltoid,  and  is  inserted 
into  the  base  of  the  styloid  process  of  the  radius. 

Relations. — By  its  superficial  surface  with  the  extensor  ossis  me- 
tacarpi  poUicis,  extensor  primi  internodii  poUicis,  and  fascia  of  the 
fore-arm.  By  its  deep  surface  M^ith  the  brachiaHs  anticus,  extensor 
carpi  radialis  longior,  tendon  of  the  biceps,  supinator  brevis,  prona- 
tor radii  teres,  flexor  carpi  radialis,  flexor  subUmis  digitorum,  flexor 
longus  pollicis,  pronator  quadratus,  radius,  musculo-spiral  nerve, 
radial  and  posterior  interosseous  nerve,  and  radial  artery  and  veins. 

This  muscle  must  be  divided  through  the  middle,  and  the  two 
ends  turned  to  either  side  to  expose  the  next  muscle. 

The  Extensor  carpi  radialis  longior  arises  from  the  external 
condyloid  ridge  below  the  preceding.  Its  tendon  passes  through 
a  groove  in  the  radius,  immediately  behind  the  styloid  process, 
to  be  inserted  into  the  base  of  the  metacarpal  bone  of  the  index 
finger. 

Relations. — By  its  superficial  surface  with  the  supinator  longus, 
extensor  ossis  metacarpi  pollicis,  extensor  primi  internodii  pollicis, 
extensor  secundi  internodii  pollicis,  radial  nerve  and  fascia  of  the 
fore-arm,  and  posterior  annular  ligament.  By  its  deep  surface  with 
the  brachialis  anticus,  extensor  carpi  radiahs  brevier,  radius  and 
wrist-joint. 

The  Extensor  carpi  radialis  brevior  is  seen  by  drawing  aside  the 
former  muscle.  It  arises  from  the  external  condyle  of  the  humerus, 
and  is  inserted  into  the  base  of  the  metacarpal  bone  of  the  middle 
finger.  Its  tendon  is  lodged  in  the  same  groove  on  the  radius  with 
the  extensor  carpi  radialis  longior. 

Relations. — By  its  superficial  surface  with  the  extensor  carpi 
radialis  longior,  extensor  ossis  metacarpi  pollicis,  extensor  primi 
internodii  pollicis,  extensor  secundi  internodii  pollicis,  fascia  of  the 
fore-arm,  and  posterior  annular  ligament.  By  its  deep  surface  with 
the  supinator  brevis,  tendon  of  the  pronator  radii  teres,  radius  and 
wrist-joint.  By  its  ulnar  border  with  the  extensor  communis  digi- 
torum. 

The  Extensor  communis  digitorum  arises  from  the  external  con- 
dyle, and  divides  into  four  tendons,  which  are  inserted  into  the  second 
and  third  phalanges  of  the  fingers.  At  the  metacarpo-phalangeal 
articulation  each  tendon  becomes  narrow  and  thick,  and  sends  a 
thin  fasciculus  upon  each  side  of  the  joint.  It  then  spreads  out  and 
receiving  the  tendon  of  the  lumbricalis  forms  a  broad  aponeurosis, 
which  covers  the  whole  of  the  posterior  aspect  of  the  finger.  At 
the  first  phalangeal  joint  the  aponeurosis  divides  into  three  slips. 
The  middle  slip  is  inserted  into  the  base  of  the  second  phalanx,  and 
the  two  lateral  portions  are  continued  onwards  on  each  side  of  the 
joint,  to  bo  inserted  into  the  last.     Little  oblifjue  tendinous  slips  con- 


EXTENSOR  COMMUNIS  DIGITOEUM. 


215 


nect  the  tendons  of  the  middle,  ring,  and  Httle  finger  as  they  cross 
the  back  of  the  hand. 


Fig-.  86  * 


Fig.  87.t 


Relations. — By  its  superficial  surface  with  the  fascia  of  the  fore- 
arm and  back  of  the  hand,  and  with  the  posterior  annular  ligament. 
By  its  deep  surface  with  the  supinator  brevis,  extensor  ossis  meta- 

*  The  superficial  layer  of  muscles  of  the  posterior  aspect  of  the  fore-arm.  1.  The 
lower  part  of  the  biceps.  2.  Part  of  the  brachialis  anticus.  3.  The  lower  part  of  the 
triceps,  inserted  into  the  olecranon.  4.  The  supinator  long-us.  5.  Tlic  extensor  carpi 
radialis  longior.  6.  The  extensor  carpi  radialis  brevier.  7.  The  tendons  of  insertion 
of  these  two  muscles.  8.  The  extensor  communis  digitorum.  9.  The  extensor  minimi 
digiti.  10.  The  extensor  carpi  ulnaris.  11.  The  anconeus.  12.  Part  of  the  flexor 
carpi  ulnaris.  13.  The  extensor  ossis  metacarpi  and  extensor  primi  inte^nodii  muscle, 
lying  together.  14.  The  extensor  secundi  internodii ;  its  tendon  is  seen  crossing  the 
two  tendons  of  the  extensor  carpi  radialis  longior  and  brevier.  1.5.  The  posterior  annu- 
lar ligament.  The  tendons  of  the  common  extensor  are  seen  upon  the  back  of  the  hand, 
and  their  mode  of  distribution  on  the  dorsum  of  the  fingers. 

t  The  deep  layer  of  muscles  on  the  posterior  aspect  of  the  fore-arm.  1.  The  lower 
part  of  the  humerus.  2.  The  olecranon.  3.  The  ulna.  4.  The  anconeus  muscle.  5. 
The  supinator  brevis  muscle.  6.  The  extensor  ossis  metacarpi  pollicis.  7.  The  exten- 
sor primi  internodii  pollicis.  8.  The  extensor  secundi  internodii  pollicis.  9.  The 
extensor  indicis.  10.  The  first  dorsal  interosseous  muscle.  The  other  tlu'ee  dorsal 
interossei  are  seen  between  the  metacarpal  bones  of  their  respective  fingers. 


216  POSTERIOR   BRACHIAL  REGION. 

carpi  pollicis,  extensor  primi  internodii,  extensor  secundi  internodii, 
extensor  indicis,  posterior  interosseous  artery  and  nerve,  wrist  joint, 
metacarpal  bones  and  interossei  muscles  and  phalanges.  By  its 
radial  J^order  with  the  extensor  carpi  radialis  longior  and  brevior. 
By  the  ulnar  border  with  the  extensor  minimi  digiti,  and  extensor 
carpi  ulnaris. 

The  Extensor  minimi  digiti  (auricularis)  is  an  ofF-set  from  the 
extensor  communis,  with  which  it  is  connected  by  means  of  a  ten- 
dinous slip.  Passing  down  to  the  inferior  extremity  of  the  ulna  it 
traverses  a  distinct  fibrous  sheath,  and  at  the  metacarpo-phalangeal 
articulation  unites  with  the  tendon  derived  from  the  long  extensor. 
The  common  tendon  then  spreads  out  into  a  broad  expansion  which 
divides  into  three  slips  to  be  inserted  as  in  the  other  fingers  into  the 
two  last  phalanges.  It  is  to  this  muscle  that  the  little  finger  owes 
its  power  of  separate  extension ;  and  from  being  called  into  action 
when  the  point  of  the  finger  is  introduced  into  the  meatus  of  the 
ear,  for  the  purpose  of  removing  unpleasant  sensations,  or  producing 
titillation,  the  muscle  was  called  by  the  older  writers  "  auricularis." 

The  Extensor  carpi  ulnaris  arises  from  the  external  condyle  and 
from  the  upper  two-thirds  of  the  border  of  the  ulna.  Its  tendon 
passes  through  the  posterior  groove  in  the  lower  extremity  of  the 
ulna,  to  be  inserted  into  the  base  of  the  metacarpal  bone  of  the  little 
finger. 

Relations. — By  its  superficial  surface  with  the  fascia  of  the  fore- 
arm, and  posterior  annular  ligament.  By  its  deep  surface  with  the 
supinator  brevis,  extensor  ossis  metacarpi  polUcis,  extensor  secundi 
internodii,  extensor  indicis,  ulna,  and  wrist  joint.  By  its  radial  bor- 
der it  is  in  relation  with  the  extensor  communis  digitorum,  and 
extensor  minimi  digiti,  and  by  the  ulnar  border  with  the  anconeus. 

The  Anconeus  appears  to  be  the  continuation  of  the  triceps :  it 
arises  from  the  outer  condyle,  and  is  inserted  into  the  olecranon  and 
triangular  surface  on  the  upper  extremity  of  the  ulna. 

Relations. — By  its  superficial  surface  with  a  strong  tendinous  apo- 
neurosis derived  from  the  triceps.  By  its  deep  surface  with  the  elbow 
joint,  orbicular  ligament,  and  slightly  with  the  supinator  brevis. 

Deep  Layer. 

Supinator  brevis, 
Extensor  ossis  metacarpi  pollicis, 
Extensor  primi  internodii  poUicis, 
Extensor  secundi  internodii  poUicis, 
Extensor  indicis. 

Dissection. — The   muscles   of    the   superficial   layer   should   be 
.  removed,  in  order  to  bring  the  deep  group  completely  into  view. 

The  Supinator  brevis  cannot  be  seen  in  its  entire  extent,  until  the 
radial  extensors  of  the  carpus  are  divided  from  their  origin.  It 
arises  from  the  external  condyle,  from  the  external  lateral  and  orbi- 
cular ligament,  and  from  the  ulna,  nnd  winds  around  the  upper  part 


EXTENSOR  MUSCLES.  217 

of  the  radius,  to  be  inserted  into  the  upper  third  of  its  obhque  Hne. 
The  posterior  interosseous  artery  and  nerve  are  seen  perforating  the 
lower  border  of  this  muscle. 

Relations. — By  its  superficial  surface  with  the  pronator  radii  teres, 
supinator  longus,  extensor  carpi  radiahs  longior  and  brevier,  exten- 
sor communis  digitorum,  extensor  carpi  ulnaris,  anconeus,  the  radial 
artery  and  veins,  the  musculo-spiral  nerve,  radial,  and  posterior 
interosseous  nerve.  By  its  deep  surface  with  the  elbow  joint  and  its 
ligaments,  the  interosseous  membrane,  and  the  radius. 

The  Extensor  ossis  metacarpi  pollicis  is  placed  immediately  below 
the  supinator  brevis.  It  arises  from  the  ulna,  interosseous  mem- 
brane, and  radius,  and  is  inserted,  as  its  name  implies,  into  the  base 
of  the  metacarpal  bone  of  the  thumb.  Its  tendon  passes  through  the 
groove  immediately  in  front  of  the  styloid  process  of  the  radius. 

Relations. — By  its  superficial  surface  with  the  extensor  carpi  ulna- 
ris, extensor  minimi  digiti,  extensor  communis  digitorum,  fascia  of 
the  fore-arm,  and  annular  ligament.  By  its  deep  surface  with  the 
ulna,  interosseous  membrane,  radius,  tendons  of  the  extensor  carpi 
radialis  longior  and  brevior,  and  supinator  longus,  and  at  the  wrist 
with  the  radial  artery.  By  its  upper  border  with  the  edge  of  the 
supinator  brevis.  By  its  lower  border  with  the  extensor  secundi  and 
primi  internodii.  The  muscle  is  crossed  by  branches  of  the  poste- 
rior interosseous  artery  and  nerve. 

The  Extensor  primi  internodii  pollicis,  the  smallest  of  the  muscles 
in  this  layer,  arises  from  the  interosseous  membrane  and  radius,  and 
passes  through  the  same  groove  with  the  extensor  ossis  metacarpi, 
to  be  inserted  into  the  base  of  the  first  phalanx  of  the  thumb. 

Relations. — The  same  as  those  of  the  preceding  muscle  with  the 
exception  of  the  extensor  carpi  ulnaris.  The  muscle  accompanies 
the  extensor  ossis  metacarpi. 

The  Extensor  secundi  internodii  pollicis  arises  from  the  ulna  and 
interosseous  membrane.  Its  tendon  passes  through  a  distinct  canal 
in  the  annular  ligament,  and  is  inserted  into  the  base  of  the  last  pha- 
lanx of  the  thumb. 

Relations. — By  its  external  surface  with  the  same  relations  as  the 
extensor  ossis  metacarpi.  By  its  deep  surface  with  the  ulna,  inter- 
osseous membrane,  radius,  wrist  joint,  radial  artery,  and  metacarpal 
bone  of  the  thumb.  The  muscle  is  placed  between  the  extensor 
primi  internodii  and  extensor  indicis. 

The  Extensor  indicis  arises  from  the  ulna  as  high  up  as  the  exten- 
sor ossis  metacarpi  pollicis,  and  from  the  interosseous  membrane. 
Its  tendon  passes  through  a  distinct  groove  in  the  radius,  and  is 
inserted  into  the  aponeurosis  formed  by  the  common  extensor  tendon 
of  the  index  finger. 

Relations. — The  same  as  those  of  the  preceding  muscle,  with  the 
exception  of  the  hand,  where  the  tendon  rests  upon  the  metacarpal 
bone  of  the  fore-finger  and  interosseous  muscle,  and  has  no  relation 
with  the  radial  artery. 

The  tendons  of  the  extensors,  as  of  the  flexor  muscles  of  the  fore- 

28 


218  MUSCLES  OF  THE  HAND. 

arm,  are  provided  with  synovial  bursK  as  they  pass  beneath  the 
annular  ligaments:  those  of  the  back  of  the  wrist  have  distinct 
sheaths,  formed  by  the  posterior  annular  ligament. 

AcLions. — The  anconeus  is  associated  in  its  action  with  the  tri- 
ceps extensor  cubiti:  it  assists  in  extending  the  fore-arm  upon  the 
arm.  The  supinator  longus  and  brevis  effect  the  supination  of  the 
fore-arm,  and  antagonize  the  two  pronators.  The  extensor  carpi 
radialis  longior  and  brevior,  and  ulnaris,  extend  the  wrist  in  opposi- 
tion to  the  two  flexors  of  the  carpus.  The  extensor  communis  digi- 
torum  restores  the  fingers  to  the  straight  position,  after  being  flexed 
by  the  two  flexors,  sublimis  and  profundus.  The  extensor  ossis 
metacarpi,  primi  internodii,  and  secundi  internodii  pollicis,  are  the 
especial  extensors  of  the  thumb,  and  serve  to  balance  the  actions  of 
the  flexor  ossis  metacarpi,  flexor  brevis,  and  flexor  longus  pollicis. 
The  extensor  indicis  gives  the  character  of  extension  to  the  index 
finger,  and  is  hence  named  "  indicator,"  and  the  extensor  minimi 
digiti  supplies  that  finger  with  the  power  of  exercising  a  distinct 
extension. 

MUSCLES  OF  THE  HAND. 

Radial  Region. 

Abductor  polUcis, 
Flexor  ossis  metacarpi  (opponens), 
Flexor  brevis  pollicis, 
Adductor  pollicis. 

Dissection. — The  hand  is  best  dissected  by  making  an  incision 
along  the  middle  of  the  palm,,  from  the  wrist  to  the  base  of  the  fingers, 
and  crossing  it  at  each  extremity  by  a  transverse  incision,  then 
turning  aside  the  flaps  of  integument.  For  exposing  the  muscles  of 
the  radial  region,  the  removal  of  the  integument  and  fascia  on  the 
radial  side  will  be  sufficient. 

The  Abductor  'pollicis  arises  from  the  scaphoid  bone  and  annular 
ligament.     It  is  inserted  into  the  base  of  the  first  phalanx. 

Relations. — By  its  superficial  surface  with  the  external  portion  of 
the  palmar  fascia.  By  its  deep  surface  with  the  flexor  ossis  meta- 
carpi. On  its  in7ier  side  it  is  separated  by  a  narrow  cellular  inter- 
space from  the  flexor  brevis  pollicis. 

This  muscle  must  be  divided  from  its  origin  and  turned  upwards, 
in  order  to  see  the  next. 

The  Flexor  ossis  metacarpi  (opponens),  arises  from  the  trapezium 
and  annular  ligament,  and  is  inserted  into  the  whole  length  of  the 
metacar]^)al  bone. 

Relations. — By  its  superficial  siirface  with  the  abductor  pollicis. 
By  its  deej)  surface  with  the  trapczio-metacarpal  articulation  and 
with  the  metacarpal  bone.     Internally  with  the  flexor  brevis  pollicis. 

The  flexor  ossis  metacarpi  may  now  be  divided  from  its  origin 
and  turned  aside,  in  order  to  show  the  next  muscle. 


ULNAR   EEGION. 


219 


Fiff.  88.* 


The  Flexo)^  brevis  poIUcis  consists  of  two  portions,  between  whichi 
lies  the  tendon  of  the  flexor  longus  polhcis.  The  external  portion 
arises  from  the  trapezium  and  an- 
nular ligament ;  the  internal  portion 
from  the  trapezoides  and  os  mag- 
num. They  are  both  inserted  into 
the  base  of  the  first  phalanx  of  the 
thumb,  having  a  sesamoid  bone  in 
each  of  their  tendons  to  protect  the 
joint. 

Relations. — By  its  superficial  sur- 
face with  the  external  portion  of  the 
palmar  fascia.  By  its  deep  surface 
with  the  adductor  polhcis,  tendon 
of  the  flexor  carpi  radialis,  and  tra- 
pezio-metacarpal  articulation.  By 
its  external  surface  with  the  flexor 
ossis  metacarpi  and  metacarpal 
bone.  By  its  inner  surface  with  the 
tendons  of  the  long  flexor  muscles 
and  first  lumbricalis. 

The  Adductor  pollicis  is  a  triangu- 
lar muscle ;  it  arises  from  the  whole 
length  of  the  metacarpal  bone  of  the 

middle  finger ;  the  fibres  converge  to  its  insertion  into  the  base  of 
the  first  phalanx. 

Relations. — By  its  anterior  surface  with  the  flexor  brevis  pollicis, 
tendons  of  the  deep  flexor  of  the  fingers,  lumbricales,  and  deep 
palmar  arch.  By  its  posterior  surface  with  the  metacarpal  bones  of 
the  index  and  middle  fingers,  the  interossei  of  the  second  interosseous 
space,  and  the  abductor  indicis. 

Ulnar  Region. 
Palmaris  brevis. 
Abductor  minimi  digiti, 
Flexor  brevis  minimi  digiti, 
Flexor  ossis  metacarpi  (adductor). 

Dissection. — Turn  aside  the  ulnar  flap  of  integument  in  the  palm 
of  the  hand ;  in  doing  this,  a  small  subcutaneous  muscle,  the  palmaris 

*  The  muscles  of  the  hand.  1.  The  annular  ligament.  2,  2.  The  origin  and  inser- 
tion of  the  abductor  pollicis  muscle ;  the  middle  portion  has  been  removed.  3.  The 
flexor  ossis  metacarpi,  or  opponens  pollicis.  4.  One  portion  of  the  flexor  brevis 
pollicis.  5.  The  deep  portion  of  the  flexor  brevis  pollicis.  6.  The  adductor  pollicis. 
7,  7.  The  lumbricales  muscles,  arising  from  the  deep  flexor  tendons,  upon  which  the 
numbers  are  placed.  The  tendons  of  the  flexor  sublimis  have  been  removed  from  the 
palm  of  the  hand.  8.  One  of  the  tendons  of  the  deep  flexor,  passing  between  the  two 
terminal  slips  of  the  tendon  of  the  flexor  sublimis  to  reach  the  last  phalanx.  9.  The 
tendon  of  the  flexor  longus  pollicis,  passing  between  the  two  portions  of  the  flexor 
brevis  to  the  last  phalanx.  10.  The  abductor  minimi  digiti.  11.  The  flexor  brevis 
minimi  digiti.  The  edge  of  the  flexor  ossis  metacarpi,  or  adductor  minimi  digiti,  is 
seen  projecting  beyond  the  inner  border  of  the  flexor  brevis.  12.  The  prominence  of 
the  pisiform  bone.     13.  The  first  dorsal  interosseous  muscle. 


220  MUSCLES  OF  THE  HAND. 

brevis,  will  be  exposed.  After  examining  this  muscle,  remove  it 
with  the  deep  fascia,  in  order  to  bring  into  view  the  muscles  of  the 
little  finger. 

The  Palmaris  brevis  arises  from  the  palmar  fascia,  and  passes 
transversely  inwards,  to  be  inserted  into  the  integument  on  the  inner 
border  of  the  hand. 

Relations. — By  its  superficial  surface  with  the  fat  and  integument 
of  the  ball  of  the  little  finger.  By  its  deep  surface  with  the  internal 
portion  of  the  palmar  fascia,  which  separates  it  from  the  ulnar 
artery,  veins,  and  nerve,  and  from  the  muscles  of  the  inner  border 
of  the  hand. 

The  Abductor  minimi  digiti  ainses  from  the  pisiform  bone,  and  is 
inserted  into  the  base  of  the  first  phalanx  of  the  little  finger. 

Relations. — By  its  superficial  surface  with  the  internal  portion  of 
the  deep  fascia  and  the  palmaris  brevis ;  by  its  deep  surface  with 
the  flexor  ossis  metacarpi  and  metacarpal  bone.  By  its  inner  border 
with  the  flexor  brevis  minimi  digiti. 

The  Flexor  brevis  minimi  digiti  arises  from  the  unciform  bone  and 
annular  ligament,  and  is  inserted  into  the  base  of  the  first  phalanx. 
It  is  sometimes  wanting. 

Relations. — By  its  supeifcial  surface  with  the  internal  portion  of 
the  palmar  fascia,  and  the  palmaris  brevis.  By  its  deep  surface  with 
the  flexor  ossis  metacarpi,  and  metacarpal  bone.  Externally  with 
the  abductor  minimi  digiti,  from  which  it  is  separated  near  its  origin 
by  the  deep  palmar  branch  of  the  ulnar  nerve  and  communicating 
artery.  Interncdly  with  the  tendons  of  the  flexor  sublimis  and  pro- 
fundus. 

The  Flexor  ossis  metacarpi  (adductor,  opponens)  aiises  from  the 
unciform  bone  and  annular  ligament,  and  is  inserted  into  the  whole 
length  of  the  metacarpal  bone  of  the  little  finger. 

Relations. — By  its  superficial  surface  with  the  flexor  brevis  and 
abductor  minimi  digiti.  By  its  deep  surface  with  the  interossei 
muscles  of  the  last  metacarpal  space,  the  metacarpal  bone,  and  the 
flexor  tendons  of  the  little  finger. 

Palmar  Region. 

Lumbricales, 
Interossei  palmares, 
Interossei  dorsales. 

The  Lumbricales,  four  in  number,  are  accessories  to  the  deep 
flexor  muscle.  They  arise  from  the  tendons  of  the  deep  flexor ;  the 
first  and  second  from  the  palmar  side,  the  third  from  the  ulnar,  and 
the  fourth  from  the  radial  side ;  and  arc  inserted,  into  the  aponeurotic 
expansion  of  the  extensor  tendons  on  the  radial  side  of  the  fingers. 
The  third,  or  that  of  the  tendon  of  the  ring  finger,  sometimes  bifur- 
cates, or  is  inserted  wholly  into  the  extensor  tendon  of  the  middle 
finger. 

Relations. — In  the  palm  of  the  hand  with  the  flexor  tendons ;   at 


INTEROSSEAL  MUSCLES.  221 

their  insertion,  with  the  tendons  of  the  interossei  and  metacarpo- 
phalangeal articulations. 

The  Palmar  interossei,  three  in  number,  are  placed  upon  the  meta- 
carpal bones,  rather  than  between  them.  They  arise  from  the  base 
of  the  metacarpal  bone  of  one  finger,  and  are  inserted  into  the  base 
of  the  first  phalanx  and  aponeurotic  expansion  of  the  extensor  tendon 
of  the  same  finger.  The  first  belongs  to  the  index  finger;  the  second, 
to  the  ring  finger ;  and  the  third,  to  the  Httle  finger ;  the  middle 
finger  being  excluded. 

Relations. — By  their  palmar  surface  with  the  flexor  tendons  and 
with  the  deep  muscles  in  the  palm  of  the  hand.  By  their  dorsal 
surface  with  the  dorsal  interossei.  On  one  side  with  the  metacarpal 
bone,  on  the  other  with  the  corresponding  dorsal  interosseous. 

On  turning  to  the  dorsum  of  the  hand,  the  four  dorsal  interossei 
are  seen  in  the  four  spaces  between  the  metacarpal  bones.  They  are 
bipenniform  muscles,  and  arise  by  two  heads,  from  the  adjoining 
sides  of  the  base  of  the  metacarpal  bones.  They  are  inserted  into 
the  base  of  the  first  phalanges,  and  aponeurosis  of  the  extensor  ten- 
dons. 

The  first  is  inserted  into  the  index  finger,  and  from  its  use  is  called 
abductor  indicis ;  the  second  and  third  are  inserted  into  the  middle 
finger,  compensating  its  exclusion  from  the  palmar  group  ;  the  fourth 
is  attached  to  the  ring  finger ;  so  that  each  finger  is  provided  with 
two  interossei,  with  the  exception  of  the  little  finger,  as  may  be 
shown  by  the  adjoining  table : 

T  J     j:         ^  one  dorsal  (abductor  indicis), 
Index  -finder  \  ^       ^  ' 

•'    °      (  one  palmar. 

Middle  finger,  two  dorsal. 

T)'      r  (  one  dorsal, 

Ring;  finger    {  i      ' 

°-^    °       I  one  palmar. 

Little  finger,   remaining  palmar. 

Relations. — By  their  dorsal  surface  with  a  thin  aponeurosis  which 
separates  them  from  the  tendons  on  the  dorsum  of  the  hand.  By 
their  palmar  surface  with  the  muscles  and  tendons  in  the  palm  of 
the  hand.  By  one  side  with  the  metacarpal  bone ;  by  the  other 
with  the  corresponding  palmar  interosseous.  The  abductor  indicis 
is  in  relation  by  its  palmar  surface,  with  the  adductor  poUicis,  the 
arteria  magna  polHcis  being  interposed.  The  radial  artery  passes 
into  the  palm  of  the  hand  between  the  two  heads  of  the  first  dorsal 
interosseous  muscle  and  the  perforating  branches  of  the  deep  palmar 
arch,  between  the  heads  of  the  other  dorsal  interossei. 

.Actions. — The  actions  of  the  muscles  of  the  hand  are  expressed 
in  their  names.  Those  of  the  radial  region  belong  to  the  thumb, 
and  provide  for  three  of  its  movements,  abduction,  adduction,  and 
fiexion.  The  ulnar  group,  in  like  manner,  is  subservient  to  the  same 
motions  of  the  little  finger,  and  the  interossei  are  abductors  and 
adductors  of  the  several  fingers.     The  lumbricales  are  accessory  in 

• 


222  MUSCLES  OP  THE  LOWER  EXTREMITY. 

their  actions  to  the  deep  flexors :  they  were  called  by  the  earlier 
anatomists,  fidicmii,  i.  e.  fiddlers'  muscles,  from  an  idea  that  they 
might  efiect  the  fractional  movements  by  which  the  performer  is 
enabled  to  produce  the  various  notes  on  that  instrument. 

In  relation  to  the  axis  of  the  hand,  the  four  dorsal  interossei  are 
abductors,  and  the  three  palmar,  adductors.  It  will  therefore  be 
seen  that  each  finger  is  provided  with  its  proper  adductor,  and  ab- 
ductor, two  flexors,  and  (with  the  exceptions  of  the  middle  and  ring 
fingers)  two  extensors.  The  thumb  has  moreover  a  flexor  and  ex- 
tensor of  the  metacarpal  bone ;  and  the  little  finger  a  flexor  of  the 
metacarpal  bone  without  an  extensor. 

MUSCLES  OF  THE  LOWER  EXTREMITY. 

The  muscles  of  the  lower  extremity  may  be  arranged  into  groups 
corresponding  with  the  different  regions  of  the  hip,  thigh,  leg,  and 
foot,  as  in  the  following  table: 

HIP. 

Gluteal  Region. 

Gluteus  maximus, 
Gluteus  medius, 
Gluteus  minimus, 
Pyriformis, 
Gemellus  superior, 
Obturator  internus, 
Gemellus  inferior. 
Obturator  externus, 
Quadratus  femoris. 

THIGH. 

Anterior  femoral  Region.  Internal  femoral  Region. 

Tensor  vaginae  femoris,  Iliacus  internus, 

Sartorius,  Psoas  magnus, 

Rectus,  Pectineus, 

Vastus  internus,  Adductor  longus. 

Vastus  externus,  Adductor  brevis, 

Crureus.  Adductor  magnus, 

Gracilis. 

Posterior  femoral  Region. 

Biceps, 

Semitendinosus. 

Semimembranosiis. 


MUSCLES  OF  THE  LOWEE  EXTREMITY. 


223 


LEG. 


Anterior  tibial  Region. 

Tibialis  anticus, 
Extensor  longus  digitorum, 
Peroneus  tertius, 
Extensor  longus  poUicis. 

Fibular  Region. 

Peroneus  longus, 
Peroneus  brevis. 


Posterior  tibial  Region. 
Superficial  Group. 
Gastrocnemius, 
Plantaris, 
Soleus. 

Deej)  \j)osterior'\  layer. 

Popliteus, 

Flexor  longus  pollicis, 
Flexor  longus  digitorum, 
Tibialis  posticus. 


FOOT. 


Dorsal  Region. 
Extensor  brevis  digitorum, 
Interossei  dorsales. 


First  Layer. 
Abductor  pollicis, 
Abductor  minimi  digiti, 
Flexor  brevis  digitorum. 

Second  Layer. 

Musculus  accessorius, 
Lumbricales. 


Plantar  Region. 


Third  Layer. 
Flexor  brevis  pollicis, 
Adductor  pollicis. 
Flexor  brevis  minimi  digiti, 
Transversus  pedis. 

Fourth  Layer. 
Interossei  plantares. 


Gluteal  Region. 

Gluteus  maximus,  Obturator  internus. 

Gluteus  medius,  Gemellus  inferior. 

Gluteus  minimus,  Obturator  externus, 

Pyriformis,  Quadratus  femoris. 
Gemellus  superior, 

Dissection. — The  subject  being  turned  on  its  face,  and  a  block 
placed  beneath  the  os  pubis  to  support  the  pelvis,  the  student  com- 
mences the  dissection  of  this  region,  by  carrying  an  incision  from 
the  apex  of  the  coccyx  along  the  crest  of  the  ilium  to  its  anterior 
superior  spinous  process ;  or  vice  versa,  if  he  be  on  the  left  side.  He 
then  makes  an  incision  from  the  posterior  fifth  of  the  crest  of  the 
iUum,  to  the  apex  of  the  trochanter  major — this  marks  the  upper 
border  of  the  gluteus  maximus;   and  a  third  incision  from   the 


224  MUSCLES  OP  THE  GLUTEAL  REGION. 

apex  of  the  coccyx  along  the  fleshy  margin  of  the  lower  border  of 
the  gluteus  maximus,  to  the  outer  side  of  the  thigh,  about  four  inches 
below  the  apex  of  the  trochanter  major.  He  then  reflects  the  in- 
tegument, superficial  fascia,  and  deep  fascia,  which  latter  is  very 
thin  over  this  muscle,  from  the  gluteus  maximus,  following  rigidly 
the  course  of  its  fibres  ;  and  having  exposed  the  muscle  in  its  entire 
extent,  he  dissects  the  integument  and  superficial  fascia  from  off'  the 
deep  fascia  which  binds  down  the  gluteus  medius,  the  other  portion 
of  this  region. 

The  Gluteus  maximus  (yXouTog,  nates)  is  the  thick,  fleshy  mass  of 
muscle,  of  a  quadrangular  shape,  which  forms  the  convexity  of  the 
nates.  In  structure,  it  is  extremely  coarse,  being  made  up  of  large 
fibres,  which  are  collected  into  fasciculi,  and  these  again  into  dis- 
tinct muscular  masses,  separated  by  deep  cellular  farrows.  It  arises 
from  the  posterior  fifth  of  the  crest  of  the  ilium,  from  the  border  of 
the  sacrum  and  coccyx,  and  from  the  great  sacro-ischiatic  ligament. 
It  passes  obliquely  outwards  and  downwards,  to  be  inserted  into  the 
rough  line  leading  from  the  trochanter  major  to  the  linea  aspera, 
and  is  continuous  by  means  of  its  tendon  with  the  fascia  lata  cover- 
ing the  outer  side  of  the  thigh.  A  large  bursa  is  situated  between 
the  broad  tendon  of  this  muscle  and  the  femur. 

Relations. — By  its  superficial  surface  with  a  thin  aponeurotic 
fascia,  which  separates  it  from  the  superficial  fascia  and  integument, 
and  with  the  vastus  externus,  a  bursa  being  interposed.  By  its  deep 
surface  with  the  gluteus  medius,  pyriformis,  gemelli,  obturator  inter- 
nus,  quadratus  femoris,  sacro-ischiatic  foramina,  great  sacro-ischiatic 
lifament,  tuberosity  of  the  ischium,  semi-membranosus,  semi-tendi- 
nosus,  biceps,  and  adductor  magnus ;  the  gluteal  vessels  and  nerves, 
ischiatic  vessels  and  nerves,  and  internal  pudic  vessels  and  nerve. 
By  its  upper  border  it  overlaps  the  gluteus  medius ;  and  by  the  lower 
border  forms  the  lower  margin  of  the  nates. 

The  gluteus  maximus  must  be  turned  down  from  its  origin,  in 
order  to  bring  the  next  muscles  into  view. 

The  Gluteus  medius  is  placed  in  front  of,  rather  than  beneath  the 
gluteus  maximus ;  and  is  covered  in  by  a  process  of  the  deep  fascia, 
which  is  very  thick  and  dense.  It  arises  from  the  outer  lip  of  the 
crest  of  the  ilium  for  four-fifths  of  its  length,  from  the  surface  of  bone 
between  that  border  and  the  superior  carved  line  on  the  dorsum  ilii, 
and  from  the  dense  fascia  above  mentioned.  Its  fibres  converge  to 
the  upper  part  of  the  trochanter  major,  into  which  its  tendon  is 
inserted. 

Relations. — By  its  superficial  surface  with  the  tensor  vaginas  femo- 
ris, gluteus  maximus,  and  a  very  thick  fascia.  By  its  deep  surface 
with  the  gluteus  minimus,  and  gluteal  vessels  and  nerves.  By  its 
lov)er  border  with  the  pyriformis  muscle. 

This  muscle  should  now  be  removed  from  its  origin  and  turned 
down,  so  as  to  expose  the  next  which  is  situated  beneath  it. 

The  Gluteus  minimus  is  a  radiated  muscle,  arising  from  the  sur- 
face of  the  dorsum  ilii,  between  the  superior  and  inferior  curved 


TYEIFORMIS OBTURATOR  INTERNUS. 


225 


Fig-.  89  * 


lines ;  its  fibres  converge  to  the  anterior  border  of  the  trochanter 
major,  into  which  it  is  inserted  by  means  of  a  rounded  tendon. 
There  is  no  distinct  hne  of  separation  between  the  gkiteus  medius 
and  minimus  anteriorly. 

Relations. — By  its  superficial  smfiace  with  the  gluteus  medius, 
and  gluteal  vessels.  By  its  deep  surface  with  the  surface  of  the 
ilium,  the  long  tendon  of  the  rectus  femoris,  and  the  capsule  of  the 
hip-joint. 

The  Pyriformis  muscle  (pyrum,  a  pear,  i.  e.  pear-shaped)  arises 
from  the  anterior  surface  of  the 
sacrum,  by  little  slips  that  are  inter- 
posed between  the  anterior  sacral 
foramina.  It  passes  out  of  the  pel- 
vis, through  the  ffreat  sacro-ischiatic 
foramen,  and  is  inserted  by  a  rounded 
tendon  into  the  trochanteric  fossa  of 
the  femur. 

Relations. — By  its  superficial  or 
external  surface  with  the  sacrum 
and  gluteus  maximus.  By  its  deep 
or  pelvic  surface  with  the  rectum, 
the  sacral  plexus  of  nerves,  the 
branches  of  the  internal  ihac  artery, 
the  great  sacro-ischiatic  notch,  and 
the  capsule  of  the  hip-joint.  By  its 
upper  border  with  the  gluteus  medius 
and  gluteal  vessels  and  nerves.  By 
its  lower  border  with  the  gemel- 
lus superior,  ischiatic  vessels  and 
nerves,  and  internal  pudic  vessels 
and  nerve. 

Immediately  below  the  pyriformis  is  a  small  slip  of  muscle,  the 
gemellus  superior  (gemellus,  double,  twin) ;  it  arises  from  the  spine 
of  the  ischium,  and  is  inserted  into  tlie  upper  border  of  the  tendon 
of  the  obturator  internus,  and  into  the  trochanteric  fossa  of  the  femur. 
The  gemellus  superior  is  not  unfrequently  wanting. 

Relations. — By  its  superficial  surface  with  the  gluteus  maximus, 
the  ischiatic  vessels  and  nerves,  and  internal  pudic  vessels  and 
nerve.  By  its  deep  surface  with  the  pelvis  and  capsule  of  the  hip- 
joint. 

The  Obturator  internus  arises  from  the  inner  surface  of  the  an- 
terior wall  of  the  pelvis,  being  attached  to  the  margin  of  hone  around 

*  The  deep  muscles  of  the  gluteal  region.  1.  The  external  surface  of  the  ilium.  2. 
The  posterior  surface  of  the  sacrum.  3.  The  posterior  sacro-iliac  ligaments.  4.  The 
tuberosity  of  tlie  ischium.  5.  The  great  or  posterior  sacro-ischiaticligament.  6".  The 
lesser  or  anterior  sacro-ischiatic  ligament.  7.  The  trochanter  major.  8.  The  gluteus 
minimis.  9.  The  pyriformis.  10.  The  gemellus  superior.  11.  The  obturator  inter- 
nus muscle,  passing  out  of  the  lesser  sacro-ischiatic  foramen.  12.  The  gemellus  infe- 
jior.  13.  The  quadratus  femoris.  14.  The  upper  part  of  the  adductor  magnus  15. 
The  vastur.  extcrnus.     16.  The  biceps.     17.  The  frracilis.     18.  The  semi-tendinosus. 

29 


226  OBTURATOR  liNTERNUS  AND  EXTERNUS. 

the  obturator  foramen,  and  to  the  obturator  membrane.  It  passes 
out  of  the  pelvis  through  the  lesser  sacro-ischiatic  foramen,  and  is 
inserted  by  a  flattened  tendon  into  the  trochanteric  fossa  of  the  femur. 
The  lesser  sacro-ischiatic  notch,  over  which  this  muscle  plays  as 
through  a  pulley,  is  faced  with  cartilage,  and  provided  with  a 
synovial  bursa  to  facilitate  its  movements.  The  tendon  of  the 
obturator  is  supported  on  each  side  by  the  two  gemelU  muscles 
(hence  their  names),  which  are  inserted  into  the  sides  of  the  tendon, 
and  appear  to  be  auxiliaries  or  superadded  portions  of  the  obturator 
internus. 

Relations. — By  its  superficial  or  posterior  surface  with  the  internal 
pudic  vessels  and  nerve,  the  obturator  fascia,  which  separates  it  from 
the  levator  ani  and  viscera  of  the  pelvis,  the  sacro-ischiatic  liga- 
ments, gluteus  maximus,  and  ischiatic  vessels  and  nerves.  By  its 
deep  or  anterior  surface  with  the  obturator  membrane  and  the 
margin  of  bone  surrounding  it,  the  cartilaginous  pulley  of  the  lesser 
ischiatic  foramen,  the  external  surface  of  the  pelvis,  and  the  capsular 
ligament  of  the  hip-joint.  By  its  upper  border,  within  the  pelvis, 
with  the  obturator  vessels  and  nerve ;  external  to  the  pelvis,  with 
the  gemellus  superior.  By  its  lower  border  with  the  gemellus  inferior. 

The  Gemellus  inferior  arises  from  the  posterior  point  of  the  tube- 
rosity of  the  ischium,  and  is  inserted  into  the  lower  border  of  the  ten- 
don of  the  obturator  internus,  and  into  the  trochanteric  fossa  of  the 
femur. 

Relations. — By  its  superficial  surface  with  the  gluteus  maximus, 
and  ischiatic  vessels  and  nerves.  By  its  deep  surface  with  the  ex- 
ternal surface  of  the  pelvis  and  capsule  of  the  hip-joint.  By  its 
upper  border  with  the  tendon  of  the  obturator  internus.  By  its 
lower  border  with  the  tendon  of  the  obturator  externus  and  quadratus 
femoris. 

In  this  region  the  tendon  only  of  the  obturator  externus  can  be 
seen>  situated  deeply  between  the  gemellus  inferior  and  the  upper 
border  of  the  quadratus  femoris.  To  expose  this  muscle  fully,  it  is 
necessary  to  dissect  it  from  the  anterior  part  of  the  thigh,  after  the 
removal  of  the  pectineus  and  adductor  longus  and  brevis  muscles. 

The  Obturator  externus  muscle  (obturare,  to  stop  up)  arises  from 
the  obturator  membrane,  and  from  the  surface  of  bone  immediately 
surrounding  it,  viz.  from  the  body  and  ramus  of  the  os  pubis  and 
ischium :  its  tendon  passes  behind  the  neck  of  the  femur,  to  be  in- 
serted with  the  external  rotator  muscles,  into  the  trochanteric  fossa 
of  the  femur. 

Relations. — By  its  superficial  or  anterior  surface  with  the  tendon 
of  the  psoas  and  iliacus,  pectineus,  adductor  brevis  and  magnus,  the 
obturator  vessels  and  nerve.  By  its  deep  or  posterior  surface  with 
the  obturator  membrane  and  the  margin  of  bone  which  surrounds 
it,  the  lower  part  of  the  capsule  of  the  hip-joint  and  the  quadratus 
femoris. 

The  Quadratus  femoris  (square-shaped)  arises  from  the  external 
border  of  the  tuberosity  of  the  ischium,  and  is  inserted  into  a  rough 


ANTERIOR   FEMORAL  REGION.  227 

line  on  the  posterior  border  of  the  trochanter  major,  which  is  thence 
named  linea  quadrati. 

Relations. — By  its  posterior  surface  with  the  gluteus  maximus,  and 
ischiatic  vessels  and  nerves.  By  its  anterior  surface  with  the  tendon 
of  the  obturator  externus  and  trochanter  minor,  a  synovial  bursa 
often  separating  it  from  the  latter.  By  its  upper  bolder  with  the 
gemellus  inferior;  and  by  the  loiver  border  with  the  adductor 
magnus. 

Actions. — The  glutei  muscles  are  abductors  of  the  thigh,  when 
they  take  their  fixed  point  from  the  pelvis.  Taking  their  fixed  point 
from  the  thigh,  they  steady  the  pelvis  on  the  head  of  the  femur — 
this  action  is  peculiarly  obvious  in  standing  on  one  leg ;  they  assist 
also  in  carrying  the  leg  forward,  in  progression.  The  gluteus 
minimus  being  attached  to  the  anterior  border  of  the  trochanter 
major,  rotates  the  limb  slightly  inwards.  The  gluteus  medius  and 
maximus,  from  their  insertion  into  the  posterior  aspect  of  the  bone, 
rotate  the  limb  outwards ;  the  latter  is,  moreover,  a  tensor  of  the 
fascia  of  the  thigh.  The  other  muscles  rotate  the  limb  outwards, 
everting  the  knee  and  foot ;  hence  they  are  named  external  rotators. 

Anterior  Femoral  Region. 

Tensor  vaginae  femoris, 

Sartorius, 

Rectus, 

Vastus  internus, 

Vastus  externus, 

Crureus. 

Dissection. — Make  an  incision  along  the  line  of  Poupart's  ligament, 
from  the  anterior  superior  spinous  process  of  the  ilium  to  the  spine 
of  the  OS  pubis ;  and  a  second,  from  the  middle  of  the  preceding 
down  the  inner  side  of  the  thigh,  and  across  the  inner  condyle  of  the 
femur,  to  the  head  of  the  tibia,  where  it  may  be  bounded  by  a  trans- 
verse incision.  Turn  back  the  integument  from  the  whole  of  this 
region,  and  examine  the  superficial  fascia ;  which  is  next  to  be  re- 
moved in  the  same  manner.  After  the  deep  fascia  has  been  well 
considered,  it  is  likewise  to  be  removed,  by  dissecting  it  oflf  in  the 
course  of  the  fibres  of  the  muscles.  As  it  might  not  be  convenient 
to  the  junior  student  to  expose  so  large  a  surface  at  once  as  ordered 
in  this  dissection,  the  vertical  incision  may  be  crossed  by  one  or  two 
transverse  incisions,  as  may  be  deemed  most  proper. 

The  Tensor  vagincE  femoris  (stretcher  of  the  sheath  of  the  thigh) 
is  a  short  flat  muscle,  situated  on  the  outer  side  of  the  hip.  It  arises 
from  the  crest  of  the  ilium,  near  to  its  anterior  superior  spinous  pro- 
cess, and  is  inserted  between  two  layers  of  the  fascia  lata  at  about 
one-fourth  down  the  thigh. 

Relations. — By  its  superficial  surface  with  the  fascia  lata  and  in- 
tegument.    By  its  deep  surface  with  the  internal  layer  of  the  fascia 


223 


SARTORIUS  AND  RECTUS. 


Fig.  90.» 


lata,  gluteus  medius,  rectus  and  vastus  externus.    By  its  innei^  border, 
near  its  origin,  "^vith  the  sartorius. 

The  Sartorius  (tailor's  muscle)  is  a  long  riband-like  muscle, 
arising  from  the  anterior  superior  spinous  pro- 
cess of  the  ilium,  and  from  the  notch  imme- 
diately below  that  process ;  it  crosses  obliquely 
the  upper  third  of  the  thigh,  descends  behind  the 
inner  condyle  of  the  femur,  and  is  inserted  by  an 
aponeurotic  expansion  into  the  inner  tuberosity 
of  the  tibia.  This  expansion  covers  in  the  inser- 
tion of  the  tendons  of  the  gracilis  and  semi-ten- 
dinosus  muscles.  The  inner  border  of  the 
sartorius  muscle  is  the  guide  to  the  operation 
for  tying  the  femoral  artery  in  the  middle  of  its 
course. 

Relations. — By  its  superficial  surface  with  the 
fascia  lata  and  some  cutaneous  nerves.  By  its 
deep  surface  with  the  psoas  and  iliacus,  rectus, 
sheath  of  the  femoral  vessels  and  saphenous 
nerves,  vastus  internus,  adductor  longus,  adduc- 
tor magnus,  gracilis,  long  saphenous  nerve, 
internal  lateral  ligament  of  the  knee-joint.  By 
its  expanded  insertion  with  the  tendons  of  the 
gracihs  and  semi-tendinosus,  a  synovial  bursa 
being  interposed.  At  the  knee-joint  its  posterior 
border  is  in  relation  with  the  internal  saphenous 
vein.  At  the  upper  third  of  the  thigh  the  sar- 
torius forms,  with  the  lower  border  "of  the 
adductor  longus,  an  isosceles  triangle,  whereof 
the  base  corresponds  with  Poupart's  ligament. 
A  perpendicular  line,  drawn  from  the  middle  of 
the  base  to  the  apex  of  this  triangle,  immediately 
overlies  the  femoral  artery  with  its  sheath. 
The  Rectus  (straight)  muscle  is  fusiform  in  its  shape  and  bipenni- 
form  in  the  disposition  of  its  fibres.  It  arises  by  two  round  tendons 
— one  from  the  anterior  inferior  spinous  process  of  the  ilium,  the 
other  from  the  upper  lip  of  the  acetabulum.  It  is  inserted  by  a 
broad  and  strong  tendon,  into  the  upper  border  of  the  patella.  It 
is  more  correct  to  consider  the  patella  as  a  sesamoid  bone,  developed 
within  the  tendon  of  the  rectus  ;  and  the  ligamentum  patellae  as  the 
continuation  of  the  tendon  to  its  insertion  into  the  spine  of  the  tibia. 
Relations. — By  its  superficial  surface  with  the  gluteus  medius, 
psoas  and  iliacus,  sartorius ;  and  for  the  lower  three-fourths  of  its 
extent,  with  the  fascia  lata.     By  its  deep  surface  with  the  capsule 

*  The  muscles  of  the  anterior  femnral  region.  1.  The  crest  of  the  ilium.  2.  Its 
anterior  superior  spinous  process.  3.  The  gluteus  medius.  4.  The  tensor  vagintP 
femoris  ;  its  insertion  into  the  fascia  lata  is  shown  inferiorly.  5.  The  sartorius.  6. 
The  rectus.  7.  The  vastus  externus.  8.  The  vastus  internus.  9.  The  patella.  10. 
The  iliaeus  internus.  11.  The  psoas  magnus.  12.  The  pectineus.  13,  Tlie  adductor 
longus.     I*!.  Part  of  the  adductor  magnus.     l.'J.  The  gracilis. 


VASTI  AND  ORUREUS.  229 

of  the  hip-joint,  the  external  circumflex  vessels,  crureus,  and  vastus 
internus  and  externus. 

The  rectus  must  now  be  divided  through  its  middle,  and  the  two 
ends  turned  aside,  to  bring  clearly  into  view  the  next  muscles. 

The  three  next  muscles  are  generally  considered  collectively  under 
the  name  of  triceps  extensor  cruris.  Adopting  this  view,  the  muscle 
surrounds  the  whole  of  the  femur,  excepting  the  rough  line  (linea 
aspera)  upon  its  posterior  aspect.  Its  division  into  three  parts  is  not 
well  defined ;  the  fleshy  mass  upon  each  side  being  distinguished  by 
the  names  of  vastus  internus  and  externus,  the  middle  portion  by 
that  of  crureus. 

The  Vastus  externus,  narrow  below  and  broad  above,  arises  from 
the  outer  border  of  the  patella,  and  is  inserted  into  the  femur  and 
outer  side  of  the  linea  aspera,  as  high  as  the  base  of  the  trochanter 
major. 

Relations. — By  its  superficial  surface  with  the  fascia  lata,  rectus, 
biceps,  semi-membranosus  and  gluteus  maximus,  a  synovial  bursa 
being  interposed.     By  its  deej)  surface  with  the  crureus  and  femur. 

The  Vastus  internus,  broad  below  and  narrow  above,  arises  from 
the  inner  border  of  the  patella,  and  is  inserted  into  the  femur  and 
inner  side  of  the  Hnea  aspera  as  high  up  as  the  anterior  inter-trochan- 
teric  line. 

Relations. — By  its  superficial  surface  with  the  psoas  and  iliacus, 
rectus,  sartorius,  femoral  artery  and  vein  and  saphenous  nerves, 
pectineus,  adductor  longus,  brevis,  and  magnus,  and  fascia  lata.  By 
its  deep  surface  with  the  crureus  and  femur. 

The  Crureus  (crus,  the  leg)  arises  from  the  upper  border  of  the 
patella,  and  is  inserted  into  the  front  aspect  of  the  femur,  as  high  as 
the  anterior  inter-trochanteric  line.  When  the  crureus  is  divided 
from  its  insertion,  a  small,  muscular  fasciculus  is  often  seen  upon  the 
lower  part  of  the  femur,  which  is  inserted  into  the  pouch  of  synovial 
membrane,  that  extends  upwards  from  the  knee-joint,  behind  the 
patella.  This  is  named,  from  its  situation,  sub-crureus,  and  would 
seem  to  be  intended  to  support  the  synovial  membrane. 

Relations. — By  its  superficial  surface  with  the  external  circumflex 
vessels,  the  rectus,  and  vastus  internus  and  externus.  By  its  deep 
surface  with  the  femur,  the  sub-crureus,  and  synovial  membrane  of 
the  knee-joint. 

Actions. — The  tensor  vaginae  femoris  renders  the  fascia  lata  tense, 
and  slightly  inverts  the  limb.  The  sartorius  flexes  the  leg  upon  the 
thigh,  and,  continuing  to  act,  the  thigh  upon  the  pelvis,  at  the  same 
time  carrying  the  leg  across  that  of  the  opposite  side,  into  the  posi- 
tion in  which  tailors  sit ;  hence  its  name.  Taking  its  fixed  point 
from  below,  it  assists  the  extensor  muscles  in  steadying  the  leg,  for 
the  support  of  the  trunk.  The  other  four  muscles  have  been  collec- 
tively named  quadriceps  extensor,  from  the  similarity  of  action. 
They  extend  the  leg  upon  the  thigh,  and  obtain  a  great  increase  of 
power  by  their  attachment  to  the  patella,  which  acts  as  a  fiilcrum. 


230  INTERNAL  FEMORAL  REGION. 

Taking  their  fixed  point  from  the  tibia,  they  steady  the  femur  upon 
the  leg,  and  the  rectus,  by  being  attached  to  the  pelvis,  serves  to 
balance  the  trunk  upon  the  lower  extremity. 

Internal  femoral  Region. 

Iliacus  internus, 
Psoas  magnus, 
Pectineus, 
Adductor  longus. 
Adductor  brevis. 
Adductor  magnus, 
Gracilis. 

Dissection. — These  muscles  are  exposed  by  the  removal  of  the 
inner  flap  of  integument  recommended  in  the  dissection  of  the 
anterior  femoral  regioil.  The  iliacus  and  psoas  arising  from  within 
the  abdomen  can  only  be  seen  in  their  entire  extent  after  the  removal 
of  the  viscera  from  that  cavity. 

The  Iliacus  internus  is  a  flat  radiated  muscle.  It  arises  from  the 
inner  concave  surface  of  the  ilium  ;  and,  after  joining  with  the 
tendon  of  the  psoas,  is  inserted  into  the  trochanter  minor  of  the 
femur. 

Relations. — By  its  anterior  surface,  within  the  pelvis,  with  the 
external  cutaneous  nerve,  and  with  the  iliac  fascia,  which  separates 
the  muscle  from  the  peritoneum,  on  the  right  from  the  caecum,  and 
on  the  left  from  the  sigmoid  flexure  of  the  colon ;  externally  to  the 
pelvis  with  the  fascia  lata,  rectus,  and  sartorius.  By  its  posterior 
surface  with  the  iliac  fossa,  margin  of  the  pelvis,  and  with  the  cap- 
sule of  the  hip-joint,  a  synovial  bursa  of  large  size  being  interposed, 
which  is  sometimes  continuous  with  the  synovial  membrane  of  the 
articulation.  By  its  inner  border  with  the  psoas  magnus  and  crural 
nerve. 

The  Psoas  magnus  (-^oa,  lumbus,  a  loin),  situated  by  the  side  of 
the  vertebral  column  in  the  loins,  is  a  long  fusiform  muscle.  It 
arises  from  the  intervertebral  substances,  part  of  the  bodies  and  bases 
of  the  transverse  processes,  and  from  a  series  of  tendinous  arches, 
thrown  across  the  constricted  portion  of  the  last  dorsal  and  four 
upper  lumbar  vertebrce.  These  arches  are  intended  to  protect  the 
lumbar  arteries  and  sympathetic  filaments  of  nerves  from  pressure, 
in  their  passage  beneath  the  muscle.  The  tendon  of  the  psoas 
magnus  unites  with  that  of  the  iliacus,  and  the  conjoined  tendon  is 
inserted  into  the  posterior  part  of  the  trochanter  minor,  a  bursa  being 
interposed. 

Relations. — By  its  anterior  surface  with  the  ligamentum  arcuatum 
internum  of  the  diaphragm,  the  kidney,  the  psoas  parvus,  genito- 
crural  nerve,  sympathetic  nerve,  its  proper  fascia,  the  peritoneum 
and  colon,  and  along  its  pelvic  border  with  the  common  and  external 
iliac  artery  and  vein.  By  its  posterior  surface  with  the  lumbar  ver- 
tebrae, the  lumbar  arteries,  quadratus  lum?x>rum,  from  which  it  is 


INTERNAL  FEMORAL  REGION.  231 

separated  by  the  anterior  layer  of  the  aponeurosis  of  the  transver- 
salis,  and  with  the  crural  nerve,  which  near  Poupart's  ligament  gets 
to  its  outer  side.  The  lumbar  plexus  of  nerves  is  situated  in  the 
substance  of  the  posterior  part  of  the  muscle.  In  the  thigh  the 
muscle  is  in  relation  with  the  fascia  lata  in  front ;  the  border  of  the 
pelvis  and  hip-joint,  from  which  it  is  separated  by  the  synovial  mem- 
brane, common  to  it  and  the  preceding  muscle,  behind ;  with  the 
crural  nerve,  and  iliacus  to  the  outer  side ;  and  with  the  femoral 
artery,  by  which  it  is  sUghtly  overlapped  to  the  inner  side. 

The  Pectineus  is  a  flat  and  quadrangular  muscle  ;  it  arises  from 
the  pectineal  hne  (pecten,  a  crust)  of  the  os  pubis,  and  is  inserted 
into  the  line  leading  from  the  anterior  inter-trochanteric  line  to  the 
linea  aspera  of  the  femur. 

Relations. — By  its  anterior  surface  with  the  pubic  portion  of  the 
fascia  lata,  which  separates  it  from  the  femoral  artery  and  vein  and 
internal  saphenous  nerve,  and  lower  down  with  the  profunda  artery. 
By  its  posterior  surface  with  the  capsule  of  the  hip-joint,  and  with  the 
obturator  externus  and  adductor  brevis,  the  obturator  vessels  being 
interposed.  By  its  external  border  with  the  psoas,  the  femoral  artery 
resting  upon  the  line  of  interval.  By  its  internal  border  with  the 
outer  edge  of  the  adductor  longus.  Obturator  hernia  is  situated 
directly  behind  this  muscle,  which  forms  one  of  its  coverings. 

The  Adductor  longus  (adducere,  to  draw  to),  the  most  superficial 
of  the  three  adductors,  arises  by  a  round  and  thick  tendon  from  the 
angle  of  the  os  pubis ;  and,  assuming  a  flattened  form,  is  inserted 
into  the  middle  third  of  the  linea  aspera. 

Relations. — By  its  anterior  surface  with  the  pubic  portion  of  the 
fascia  lata,  and  near  its  insertion  with  the  femoral  artery  and  vein. 
By  its  posterior  surface  with  the  adductor  brevis  and  magnus,  the 
anterior  branches  of  the  obturator  vessels  and  nerves,  and  near  its 
insertion  with  the  profunda  artery  and  vein.  By  its  07Uer  border 
with  the  pectineus,  and  by  the  inner  border  with  the  gracilis. 

The  pectineus  must  be  divided  near  its  origin  and  turned  out- 
wards, and  the  adductor  longus  through  its  middle,  turning  its  ends 
to  either  side,  to  bring  into  view  the  adductor  brevis. 

The  Adductor  brevis,  placed  beneath  the  pectineus  and  adductor 
longus,  is  fleshy,  and  thicker  than  the  adductor  longus ;  it  arises 
from  the  body  and  ramus  of  the  os  pubis,  and  is  inserted  into  the 
upper  third  of  the  linea  aspera. 

Relations. — By  its  anterior  surface  with  the  pectineus,  adductor 
longus,  and  anterior  branches  of  the  obturator  vessels  and  nerve. 
By  its  posterior  surface  with  the  adductor  magnus,  and  posterior 
branches  of  the  obturator  vessels  and  nerve.  By  its  outer  border 
with  the  obturator  externus,  and  conjoined  tendon  of  the  psoas  and 
iliacus.  By  its  inner  border  with  the  gracilis  and  adductor  magnus. 
The  adductor  brevis  is  pierced  near  its  insertion  by  the  middle  per- 
forating artery. 

The  adductor  brevis  may  now  be  divided  from  its  origin  and 
turned  outwards,  or  its  inner  two-thirds  may  be  cut  away  entirely. 


232  POSTERIOR  FEMORAL  REGION. 

when  the  adductor  magnus  muscle  will  be  exposed  in  its  entire 
extent. 

The  Adductor  magnus  is  a  broad  triangular  muscle,  forming  a 
septum  of  division  between  the  muscles  situated  on  the  anterior  and 
those  oh  the  posterior  aspect  of  the  thigh.  It  arises  by  fleshy  fibres 
from  the  ramus  and  side  of  the  tuberosity  of  the  ischium  ;  and  rad lat- 
ino- in  its  passage  outwards  is  insei^ted  into  the  whole  length  of  the 
linea  aspera,  and  inner  condyle  of  the  femur.  The  adductor  magnus 
is  pierced  by  five  openings :  the  three  superior,  for  the  three  perfo- 
rating arteries ;  and  the  fourth,  for  the  termination  of  the  profunda. 
The  fifth  is  the  large  oval  opening  in  the  tendinous  portion  of  the 
muscle,  that  gives  passage  to  the  femoral  vessels. 

Relations. — By  its  anterior  surface  with  the  pectineus,  adductor 
brevis,  adductor  longus,  femoral  artery  and  vein,  profunda  artery 
and  vein,  with  their  branches,  and  with  the  posterior  branches  of 
the  obturator  vessels  and  nerve.  By  its  posterior  surface  with  the 
semi-tendinosus,  semi-membranosus,  biceps,  and  gluteus  maximus. 
By  its  inner  border  with  the  gracilis  and  sartorius.  By  its  upper 
border  with  the  obturator  externus,  and  quadratus  femoris. 

The  Gracilis  (slender)  is  situated  along  the  inner  border  of  the 
thigh.  It  arises  by  a  broad  but  very  thin  tendon,  from  the  edge  of 
the  ramus  of  the  os  pubis  and  ischium ;  and  is  inserted  by  a  rounded 
tendon  into  the  inner  tuberosity  of  the  tibia,  beneath  the  expansion 
of  the  sartorius. 

Relations. — By  its  inner  or  superficial  surface  with  the  fascia  lata, 
and  below  with  the  sartorius  and  internal  saphenous  nerve ;  the  in- 
ternal saphenous  vein  crosses  it  lying  superficially  to  the  fascia  lata. 
By  its  outer  or  deep  surface  with  the  adductor  longus,  brevis,  and 
magnus,  and  the  internal  lateral  Hgament  of  the  knee-joint,  from 
which  it  is  separated  by  a  synovial  bursa  common  to  the  tendons  of 
the  gracilis  and  semi-tendinosus. 

Actions. — The  ihacus,  psoas,  pectineus,  and  adductor  longus 
muscles  bend  the  thigh  upon  the  pelvis,  and,  at  the  same  time,  from 
the  obliquity  of  their  insertion  into  the  lesser  trochanter  and  linea 
aspera,  rotate  the  entire  limb  outwards ;  the  pectineus  and  adductors 
adduct  the  thigh  powerfully ;  and,  from  the  manner  of  their  insertion 
into  the  linea  aspera,  they  assist  in  rotating  the  limb  outwards.  The 
gracilis  is  likewise  an  adductor  of  the  thigh ;  but  contributes  also 
to  the  flexion  of  the  leg,  by  its  attachment  to  the  inner  tuberosity  of 
the  tibia. 

Posterior  femoral  Region. 

Biceps, 

Semi-tendinosus, 

Semi-membranosus. 

Dissection. — llcmove  the  integument  and  fascia  on  the  posterior 
part  of  the  thigh  by  two  flaps,  as  on  the  anterior  region,  and  turn 
aside  the  gluteus  maximus  from  the  upper  part ;  the  muscles  may 
then  be  examined. 


POSTERIOR  FEMORAL  REGION. 


233 


Fio-.  91  * 


The  Biceps  Jlexor  cruris  (bis,  double,  xs^aXii,  head)  arises  by  two 
heads,  one  by  a  common  tendon  with  the  semi-tendinosus ;  the  other 
muscular,  and  much  shorter,  from  the  lower  two-thirds  of  the 
external  border  of  the  linea  aspera.  This  muscle  forms  the  outer 
hamstring,  and  is  inserted  by  a  strong  tendon  into  the  head  of  the 
fibula. 

Relations. — By  its  superficial  or  posterior  surface  with  the  gluteus 
maximus  and  fascia  lata.  By  its  deep  or  an- 
terior surface  with  the  semi-membranosus,  ad- 
ductor magnus,  vastus  externus,  the  great 
sciatic  nerve,  popliteal  artery  and  vein,  and 
near  its  insertion  with  the  external  head  of  the 
gastrocnemius,  and  plantaris.  By  its  inner 
border  with  the  semi-tendinosus,  and  in  the 
popliteal  space  with  the  popliteal  artery  and 
vein. 

The  Semi-tendinosus,  remarkable  for  its 
long  tendon,  arises  in  common  with  the  long 
head  of  the  biceps,  from  the  tuberosity  of  the 
ischium.  It  is  inserted  into  the  inner  tubero- 
sity of  the  tibia. 

Relations. — By  its  superficial  surface  with 
the  gluteus  maximus,  fascia  lata,  and  at  its 
insertion  with  the  synovial  bursa  which  sepa- 
rates its  tendon  from  the  expansion  of  the 
sartorius.  By  its  deep  surface  with  the  semi- 
membranosus, adductor  magnus,  internal  head 
of  the  gastrocnemius,  and  internal  lateral  liga- 
ment of  the  knee-joint,  the  synovial  bursa  com- 
mon to  it,  and  the  tendon  of  the  gracilis  being 
mterposed.  By  its  inner  border  with  the  gra- 
cilis ;  and  by  its  outer  border  with  the  biceps. 

These  two  muscles  must  be  dissected  from 
the  tuberosity  of  the  ischium,  to  bring  into 
view  the  origin  of  the  next. 

The  Semi-membranosus,  remarkable  for  the 
tendinous  expansion  upon  its  anterior  and 
posterior  surface,  arises  from  the  tuberosity  of  the  ischium,  in 
front  of  the  common  origin  of  the  two  preceding  muscles.  It  is 
inserted  into  the  posterior  part  of  the  inner  tuberosity  of  the  tibia ; 
at  its  insertion  the  tendon  splits  into  three  portions,  one  of  which 
is  inserted  in  a  groove  on  the  inner  side  of  the  head  of  the  tibia, 

*  The  muscles  of  the  posterior  femoral  and  gluteal  region.  1.  The  gluteus  medius. 
2.  The  gluteus  maximus.  3.  The  vastus  externus  covered  in  by  fascia  lata.  4.  The 
head  of  the  biceps.  5.  Its  short  head.  6.  The  semi-tendinosus.  7.  The  semi-mem- 
branosus. 8.  The  gracilis.  9.  A  part  of  the  inner  border  of  the  adductor  magnus. 
10.  The  edge  of  the  sartorius.  11.  The  popliteal  space.  12.  The  gastrocnemius  mus- 
cle ;  its  two  heads.  The  tendon  of  the  biceps  forms  the  outer  hamstring  ;  and  the  sar- 
torius  with  the  tendons  of  the  gracilis,  semi-tendinosus,  and  semi-membranosus,  the 
inner  hamstring. 

30 


234  ANTERIOR  TIBIAL  REGION. 

beneath  the  internal  lateral  ligament.  The  second  is  continuous 
with  an  aponeurotic  expansion  that  binds  down  the  popliteus 
muscle — the  popliteal  fascia ;  and  the  third  turns  upwards  and  out- 
wards to  the  external  condyle  of  the  femur,  forming  the  middle  por- 
tion of  the  posterior  ligament  of  the  knee-joint  (ligamentum  posticum 
Winslowii). 

The  tendons  of  the  two  last  muscles,  viz.  the  semi-tendinosus  and 
semi-membranosus,  with  those  of  the  gracilis  and  sartorius,  form  the 
inner  hamstring. 

Relations. — By  its  superficial  surface  with  the  gluteus  maximus, 
biceps,  semi-tendinosus,  fascia  lata,  and  at  its  insertion  with  the  tendi- 
nous expansion  of  the  sartorius.  By  its  deep  surface  with  the  quad- 
ratus  femoris,  adductor  magnus,  internal  head  of  the  gastrocnemius, 
the  knee-joint,  from  which  it  is  separated  by  a  synovial  membrane, 
and  the  popliteal  artery  and  vein.  By  its  inner  border  with  the  gra- 
cilis. By  its  outer  harder  with  the  great  ischiatic  nerve,  and  in  the 
popliteal  space,  with  the  popliteal  artery  and  vein. 

If  the  semi-membranosus  muscle  be  turned  down  from  its  origin, 
the  student  will  bring  into  view  the  broad  and  radiated  expanse  of 
the  adductor  magnus,  upon  which  the  three  flexor  muscles  above 
described  rest. 

Actions. — These  three  hamstring  muscles  are  the  direct  flexors  of 
the  leg  upon  the  thigh ;  and,  by  taking  their  origin  from  below, 
they  balance  the  pelvis  on  the  lower  extremities.  The  biceps  from 
the  obliquity  of  its  direction  everts  the  leg  when  partly  flexed,  and 
the  semi-tendinosus  turns  the  leg  inwards  when  in  the  same  state  of 
flexion. 

Anterior  tibial  Region. 

Tibialis  anticus. 
Extensor  longus  digitorum, 
Peroneus  tertius, 
Extensor  proprius  pollicis. 

Dissection. — The  dissection  of  the  anterior  tibial  region  is  to  be 
commenced  by  carrying  an  incision  along  the  middle  of  the  leg,  mid- 
way between  the  tibia  and  the  fibula,  from  the  knee  to  the  ankle, 
and  bounding  it  inferiorly  by  a  transverse  incision,  extending  from 
one  malleolus  to  the  other.  And  to  expose  the  tendons  on  the  dor- 
sum of  the  foot,  the  longitudinal  incision  may  be  carried  onwards  to 
the  outer  side  of  the  base  of  the  great  toe,  and  be  terminated  by 
another  incision  directed  across  the  heads  of  the  metatarsal  bones. 

The  Tibialis  anticus  muscle  (flexor  tarsi  tibialis)  arises  from  the 
upper  two-thirds  of  the  tibia,  from  the  interosseous  membrane,  and 
from  the  deep  fascia;  its  tendon  passes  through  a  distinct  sheath  in 
the  annular  ligament,  and  is  inserted  into  the  inner  side  of  the 
internal  cuneiform  bone,  and  base  of  the  metatarsal  bone  of  the 
great  toe. 

Relations. — By  its  anterior  surface  with  the  deep  fascia,  from 
which  many  of  its  superior  fibres  arise,  and  with  the  anterior  annu- 


EXTENSOR   PROPRIUS  POLLICIS.  235 

lar  ligament.  6y  its  ■posterior  surface  with  the  interosseous  mem- 
brane, tibia,  ankle-joint,  and  bones  of  the  tarsus  with  their  articula- 
tions. By  its  internal  surface  with  the  tibia.  By  the  external  sur- 
face with  the  extensor  longus  digitorum,  extensor  proprius  pollicis, 
and  with  the  anterior  tibial  vessels  and  nerve. 

The  Extensor  longus  digitorum  arises  from  the  head  of  the  tibia, 
from  the  upper  three-fourths  of  the  fibula,  from  the  interosseous 
membrane,  and  from  the  deep  fascia.  Below,  it  divides  into  four 
tendons,  which  pass  beneath  the  annular  ligament,  to  be  inserted 
into  the  second  and  third  phalanges  of  the  four  lesser  toes.  The 
mode  of  insertion  of  the  extensor  tendons,  both  in  the  hand  and  in 
the  foot,  is  remarkable ;  each  tendon  spreads  into  a  broad  aponeu- 
rosis over  the  first  phalanx ;  this  aponeurosis  divides  into  three  sHps, 
the  middle  one  is  inserted  into  the  base  of  the  second  phalanx,  and 
the  two  lateral  slips  are  continued  onwards,  to  be  inserted  into  the 
base  of  the  third. 

Relations. — By  its  anterior  surface  with  the  deep  fascia  of  the  leg 
and  foot,  and  with  the  anterior  annular  ligament.  By  its  posterior 
surface  with  the  interosseous  membrane,  fibula,  ankle-joint,  extensor 
brevis  digitorum,  which  separates  its  tendons  from  the  tarsus,  and 
with  the  metatarsus  and  phalanges.  By  its  inner  surface  with  the 
tibiahs  anticus,  extensor  proprius  pollicis,  and  anterior  tibial  vessels. 
By  its  outer  border  with  the  peroneus  longus  and  brevis. 

The  Peroneus  tertius  (flexor  tarsi  fibularis)  arises  from  the  lower 
fourth  of  the  fibula,  and  is  inserted  into  the  base  of  the  metatarsal 
bone  of  the  little  toe.  Although  apparently  but  a  mere  division  or 
continuation  of  the  extensor  longus  digitorum,  this  muscle  may  be 
looked  upon  as  analogous  to  the  flexor  carpi  ulnaris  of  the  fore-arm. 
Sometimes  it  is  altogether  wanting. 

The  Extensor  proprius  'pollicis  lies  between  the  tibialis  anticus 
and  extensor  longus  digitorum.  It  arises  from  the  lower  two-thirds 
of  the  fibula  and  interosseous  membrane.  Its  tendon  passes  through 
a  distinct  sheath  in  the  annular  ligament,  and  is  inserted  into  the 
base  of  the  last  phalanx  of  the  great  toe. 

Relations. — By  its  anterior  surface  with  the  deep  fascia  of  the  leg 
and  foot,  and  with  the  anterior  annular  ligament.  By  its  posterior 
surface  with  the  interosseous  membrane,  the  fibula,  the  tibia,  the 
ankle-joint,  the  extensor  brevis  digitorum,  and  the  bones  and  articu- 
lations of  the  great  toe.  It  is  crossed  upon  this  aspect  by  the  ante- 
rior tibial  vessels  and  nerve.  By  its  outer  side  with  the  extensor 
longus  digitorum,  and  in  the  foot  with  the  dorsalis  pedis  artery  and 
veins  ;  the  outer  side  of  its  tendon  upon  the  dorsum  of  the  foot  being 
the  guide  to  these  vessels.  By  its  inner  side  with  the  tibialis  anti- 
cus, and  with  the  anterior  tibial  vessels. 

Actions. — The  tibialis  anticus  and  peroneus  tertius  are  direct  flexors 
of  the  tarsus  up'on  the  leg;  acting  in  conjunction  with  the  tibialis 
posticus  they  direct  the  foot  inwards,  and  with  the  peroneus  longus 
and  brevis  outwards.  They  assist  also  in  preserving  the  flatness  of 
the  foot  during  progression.     The  extensor  longus  digitorum  and 


236  POSTERIOR  TIBIAL  REGION. 

extensor  proprius  poUicis,  are  direct  extensors  of  the  phalanges ;  but 
continuing-  their  action,  they  assist  the  tibiahs  anticus  and  peroneus 
tertius,  in  flexing  the  entire  foot  upon  the  leg.  Taking  their  origin 
from  below,  they  increase  the  stabihty  of  the  ankle-joint. 

Posterior  tibial  Region. 

Superficial  Group. 

Gastrocnemius, 

Plantaris, 

Soleus. 

Dissection. — Make  an  incision  from  the  middle  of  the  popliteal 
space  down  the  middle  of  the  posterior  part  of  the  leg  to  the  heel, 
bounding  it  inferiorly  by  a  transverse  incision  passing  between  the 
two  malleoli.  Turn  aside  the  flaps  of  integument  and  remove  the 
fasciae  from  the  whole  of  this  region;  the  gastrocnemius  muscle  will 
then  be  exposed. 

The  Gasti^ocnemius  (/ao'TgoxvPjixiov,  the  beUied  part  of  the  leg)  arises 
by  two  heads  from  the  two  condyles  of  the  femur,  the' inner  head 
being  the  longest.  They  unite  to  form  the  beautiful  muscle  so  cha- 
racteristic of  this  region  of  the  Hmb.  It  is  inserted,  by  means  of  the 
tendo  Achillis,  into  the  lower  part  of  the  posterior  tuberosity  of  the 
OS  calcis,  a  synovial  bursa  being  placed  between  that  tendon  and 
the  upper  part  of  the  tuberosity.  The  gastrocnemius  must  be 
removed  from  its  origin,  and  turned  down,  in  order  to  expose  the 
next  muscle. 

Relations. — By  its  supei^cial  surface  with  the  deep  fascia  of  the 
leg  which  separates  it  from  the  external  saphenous  vein,  and  with 
the  external  saphenous  nerve.  By  its  deep  surface  with  the  lateral 
portions  of  the  posterior  ligament  of  the  knee-joint,  the  popliteus, 
plantaris,  and  soleus.  The  internal  head  of  the  muscle  rests  against 
the  posterior  surface  of  the  internal  condyle  of  the  femur;  the  exter- 
nal head  against  the  outer  side  of  the  external  condyle.  In  the  lat- 
ter a  sesamoid  bone  is  sometimes  found. 

The  Plantaris  (planta,  the  sole  of  the  foot),  an  extremely  diminu- 
tive muscle  situated  between  the  gastrocnemius  and  soleus,  arises 
from  the  outer  condyle  of  the  femur ;  and  is  inserted,  by  its  long  and 
delicately  slender  tendon,  into  the  inner  side  of  the  posterior  tube- 
rosity of  the  OS  calcis,  by  the  side  of  the  tendo  Achilhs;  having  crossed 
obliquely  between  the  two  muscles. 

The  Soleus  (solea,  a  sole)  is  the  broad  muscle  upon  which  the 
plantaris  rests.  It  arises  from  the  hearl  and  upper  third  of  the  fibula, 
from  the  oblique  line  and  middle  third  of  the  tibia.  Its  fibres  con- 
verge to  the  tendo  Achillis,  by  which  it  is  inserted  into  the  posterior 
tuberosity  of  the  os  calcis.  Between  tlie  fibular  and  tibial  origins  of 
this  muscle  is  a  tendinous  arch,  beneath  which  the  popliteal  vessels 
and  nerve  pass  into  the  leg. 

Relations. — By  its  superficial  surface  with  the  gastrocnemius  and 


POSTERIOR  TIBIAL  REGION. 


237 


plantaris.  By  its  deep  surface  with  the  intermuscular  fascia,  which 
separates  it  from  the  flexor  longus  digitorum,  tibiahs  posticus,  flexor 
longus  polUcis,  from  the  posterior  tibial  vessels  and  nerve,  and  from 
the  peroneal  vessels. 

Fig.  92  * 


Actions. — The  three  muscles  of  the  calf  draw  powerfully  on  the 
OS  calcis,  and  lift  the  heel ;  continuing  their  action,  they  raise  the 
entire  body.  This  action  is  attained  by  means  of  a  lever  of  the 
second  power,  the  fulcrum  (the  toes)  being  at  one  end,  the  weight 

*  The  muscles  of  the  anterior  tibial  region.  1.  The  extensor  muscles  inserted  into 
the  patella.  2.  The  subcutaneous  surface  of  the  tibia.  3.  The  tibialis  anticus.  4. 
The  extensor  communis  digitorum.  5.  The  extensor  proprius  pollicis.  6.  The  pero- 
neus  tertius.  7.  The  peroneus  longus.  8.  The  pcroneus  brcvis.  9,  9.  The  borders 
of  the  soleus  muscle.  10.  A  part  of  the  inner  belly  of  the  gastrocnemius.  11.  The 
extensor  brevis  digitorum;  the  tendon  in  front  of  this  number  is  tliat  of  the  peroneus 
tertius ;  and  that  behind  it,  the  tendon  of  the  pcroneus  brevis. 

t  The  superficial  muscles  of  the  posterior  aspect  of  the  leg.  1.  The  biceps  muscle 
forming  the  outer  hamstring.  2.  The  tendons  forming  the  inner  hamstring.  3.  The 
popliteal  space.  4.  The  gastrocnemius  muscle.  5,  5.  Tlie  soleus.  6.  The  tcndo 
Achillis.  7.  The  posterior  tuberosity  of  the  os  calcis,  8.  Tlie  tendons  of  the  pcroneus 
longus  and  brevis  muscles  passing  behind  the  outer  ankle.  9.  The  tendons  of  the  deep 
layer  passing  into  the  foot  behind  the  inner  ankle. 


238  POSTERIOR  TIBIAL  REGION. 

(the  body  supported  on  the  tibia)  in  the  middle,  and  the  power  (these 
muscles)  at  the  other  extremity. 

They  are,  therefore,  the  walking  muscles,  and  perform  all  move- 
ments that  i-equire  the  support  of  the  whole  body  from  the  ground, 
as  dancing,  leaping,  &c.  Taking  their  fixed  point  from  below,  they 
steady  the  leg  upon  the  foot. 

Deep  layer.    ' 

Popliteus, 

Flexor  longus  pollicis, 
Flexor  longus  digitorum, 
Tibialis  posticus. 

Dissection. — After  the  removal  of  the  soleus,  the  deep  layer  will 
be  found  bound  down  by  an  inter-muscular  fascia,  which  is  to  be  dis- 
sected away ;  the  muscles  may  then  be  examined. 

The  Popliteus  muscle  (poples,  the  ham  of  the  leg)  forms  the  floor 
of  the  popliteal  region  at  its  lower  part,  and  is  bound  tightly  down 
by  a  strong  fascia  derived  from  the  middle  slip  of  the  tendon  of  the 
semi-membranosus  muscle.  It  mnses  by  a  rounded  tendon  from  a 
deep  groove  on  the  outer  side  of  the  external  condyle  of  the  femur, 
beneath  the  external  lateral  ligament ;  and  spreading  obliquely  over 
the  head  of  the  tibia,  is  inserted  into  the  surface  of  bone  above  its 
oblique  line.  This  line  is  often  called,  from  being  the  limit  of  inser- 
tion of  the  popliteus  muscle,  the  popliteal  line. 

Relations. — By  its  superficial  surface  with  a  thick  fascia  which 
separates  it  from  the  two  heads  of  the  gastrocnemius,  the  plantaris, 
and  the  popliteal  vessels  and  nerve.  By  its  deepj  surface  with  the 
articulation  of  the  knee-joint  and  with  the  upper  part  of  the  tibia. 

The  Flexor  longus  pollicis  is  the  most  superficial  of  the  three  next 
muscles.  It  arises  from  the  lower  two-thirds  of  the  fibula,  passes 
through  a  groove  in  the  astragalus  and  os  calcis,  which  is  converted 
by  tendinous  fibres  into  a  distinct  sheath  lined  by  a  synovial  mem- 
brane into  the  sole  of  the  foot ;  it  is  inserted  into  the  base  of  the  last 
phalanx  of  the  great  toe. 

Relations. — By  its  superfixial  surface  with  the  intermuscular 
fascia,  which  separates  it  from  the  soleus  and  tendo  Achillis.  By 
its  deep  surface  with  the  tibialis  posticus,  fibula,  fibular  vessels,  inter- 
osseous membrane,  and  ankle-joint.  By  its  07iter  border  with  the 
peroneus  longus  and  brevis.  By  its  inner  border  with  the  flexor 
longus  digitorum.  In  the  foot,  the  tendon  of  the  flexor  longus  pol- 
licis is  connected  with  that  of  the  flexor  longus  digitorum  by  a  short 
tendinous  slip. 

The  Flexor  longus  digitorum  (pcrforans)  arises  from  the  surface  of 
the  tibia,  immediately  below  the  popliteal  line.  Its  tendon  passes 
through  a  shoatli  common  to  it  and  the  tibialis  posticus  behind  the 
inner  malleolus;  it  then  passes  through  a  second  sheath  which  is 
connected  with  a  groove  in  the  astragalus  and  os  calcis,  into  the 
sole  of  the  foot,  where  it  divides  into  four  tendons,  which  are  inserted 


TIBIALIS  POSTICUS. 


239 


into  the  base  of  the  last  phalanx  of  the  four  lesser  toes,  perforating 
the  tendons  of  the  flexor  brevis  digitorurn. 

Relations. — By  its  sicpey-ficial  surface  with  the  intermuscular 
fascia,  which  separates  it  from  the  soleus,  and  with  the  posterior 
tibial  vessels  and  nerve.  By  its  deep  surface  with  the  tibia  and 
tibialis  posticus.  In  the  sole  of  the  foot  its  tendon  is  in  relation  with 
the  abductor  polhcis  and  flexor  brevis  digitorurn,  which  lie  superfi- 
cially to  it,  and  it  crosses  the  tendon  of  the  flexor  longus  polUcis. 
At  the  point  of  crossing  it  receives  the  tendinous  slip  of  communi- 
cation from  the  latter. 

The  flexor  longus  polhcis  must  now  be  removed  from  its  origin, 
and  the  flexor  longus  digitorum  drawn  aside,  to  bring  into  view  the 
entire  extent  of  the  tibialis  posticus. 

The  Tibialis  posticus  (extensor  tarsi  tibiahs)  lies  upon  the  interos- 
seous membrane,  between  the  two  bones  of  the  leg. 
It  arises  by  two  heads  from  the  adjacent  sides  of  Fig.  94.* 
the  tibia  and  fibula  their  whole  length,  and  from 
the  interosseous  membrane.  Its  tendon  passes 
inwards  beneath  the  tendon  of  the  flexor  lono;us 
digitorum,  and  runs  in  the  same  sheath;  it  then  #'i  ?=   .V 

passes  through  a  proper  sheath  over  the  deltoid  liga- 
ment, and  beneath  the  calcaneo-scaphoid  articula-        ^  [l^^vl^]  T  | 
tion,   to    be   inserted    into   the   tuberosity  of   the  '^^"t^^-  .^- 

scaphoid  and  internal  cuneiform  bone.  While  in 
the  common  sheath  behind  the  internal  malleolus, 
the  tendon  of  the  tibiahs  posticus  lies  internally  to 
that  of  the  flexor  longus  digitorum,  from  which  it  is 
separated  by  a  thin  fibrous  partition.  A  sesamoid 
bone  is  usually  met  with  in  the  tendon  close  to  its 
insertion. 

Relations. — By  its  superficial  surface  with  the  in- 
termuscular septum,  the  flexor  longus  pollicis,  flexor 
longus  digitorum,  posterior  tibial  vessels  and  nerve, 
peroneal  vessels,  and  in  the  sole  of  the  foot  with  the 
abductor  pollicis.  By  its  deep  surface  with  the 
interosseous  membrane,  the  fibula  and  tibia,  the  ankle 
joint,  and  the  astragalus.  -  The  anterior  tibial  artery 
passes  between  the  two  heads  of  the  muscle. 

The  student  will  observe  that  the  two  latter  mus- 
cles change  their  relative  position  to  each  other  in  r'  ^-^ 
their  course.  Thus,  in  the  leg,  the  position  of  the  "  y 
three  muscles   from   within  outwards,  is  —  flexor 

*  The  deep  layer  of  muscles  of  the  posterior  tibial  region.  1.  The  lower  extremity 
of  the  femur.  2.  The  ligamentum  posticum  Winslowii.  3.  The  tendon  of  the  semi- 
membranosus  muscle  dividing  into  its  three  slips.  4.  The  internal  lateral  ligament  of 
the  knee-joint.  5.  The  external  lateral  ligament.  6.  Tlie  popliteus  muscle.  7.  Tlie 
flexor  longus  digitorum.  8.  The  tibialis  posticus.  9.  The  flexor  longus  pollicis.  10. 
The  peroneus  longus  muscle.  11.  The  peroneus  brevis.  12.  The  tendo  Achillis 
divided  at  its  insertion  into  the  os  calcis.  1.3.  The  tendons  of  the  tibialis  posticus  and 
flexor  longus  digitorum  muscles,  just  as  they  are  about  to  pass  beneath  the  internal 
annular  ligament  of  the  ankle  ;  the  interval  between  the  latter  tendon  and  the  tendon 
of  the  flexor  longus  pollicis  is  occupied  by  the  posterior  tibial  vessels  and  nerve. 


240  FIBULAR  REGION. 

longus  digitorum,  tibialis  posticus,  flexor  longus  pollicis.  At  the 
inner  malleolus,  the  relation  of  the  tendons  is — tibiahs  posticus, 
flexor  longus  digitorum,  both  in  the  same  sheath ;  then  a  broad 
groove,  which  lodges  the  posterior  tibial  artery,  venae  comites,  and 
nerve ;  "and  lastly,  the  flexor  longus  pollicis. 

Actions. — The  popliteus  is  a  flexor  of  the  tibia  upon  the  thigh, 
carrying  it  at  the  same  time  inwards  so  as  to  invert  the  leg.  The 
flexor  longus  polhcis,  and  flexor  longus  digitorum  are  the  long 
flexors  of  the  toes ;  their  tendons  are  connected  in  the  foot  by  a 
short  tendinous  band,  hence  they  necessarily  act  together.  The 
tibialis  posticus  is  an  extensor  of  the  tarsus  upon  the  leg,  and  an 
antagonist  to  the  tibialis  anticus.  It  combines  with  the  tibalis  anticus 
in  adduction  of  the  foot. 

Fibular  Region. 

Peroneus  longus, 
Peroneus  brevis. 

Dissection. — These  muscles  are  exposed  by  continuing  the  dissec- 
tion of  the  anterior  tibial  region  outwards  beyond  the  fibula,  to  the 
border  of  the  posterior  tibial  region. 

The  Peroneus  longus  ('tts^ovt),  fibula,  extensor  tarsi  fibularis  longior) 
muscle  arises  from  the  upper  third  of  the  outer  side  of  the  fibula, 
and  terminates  in  a  long  tendon,  which  passes  behind  the  external 
malleolus,  and  obliquely  across  the  sole  of  the  foot,  through  the 
groove  in  the  cuboid  bone,  to  be  inserted  into  the  base  of  the  meta- 
tarsal bone  of  the  great  toe.  Its  tendon  is  thickened  when  it  glides 
behind  the  external  malleolus,  and  a  sesamoid  bone  is  developed  in 
that  part  which  plays  upon  the  cuboid  bone. 

Relations. — By  its  superficial  surface  with  the  fascia  of  the  leg 
and  foot.  By  its  deep  surface  with  the  fibula,  peroneus  brevis,  os 
calcis,  and  cuboid  bone,  and  near  the  head  of  the  fibula  with  the 
fibular  nerve.  By  its  anterior  border  it  is  separated  from  the  extensor 
longus  digitorum  by  the  attachment  of  the  fascia  of  the  leg  to  the 
fibula ;  and  by  the  posterior  border  by  the  same  medium  from  the 
soleus  and  flexor  longus  pollicis.  The  peroneus  longus  is  furnished 
with  three  tendinous  sheaths  and  as  many  synovial  membranes ;  the 
first  is  situated  behind  the  external  malleolus,  and  is  common  to  this 
muscle  and  the  peroneus  brevis,  the  second  on  the  outer  side  of  the 
OS  calcis,  and  the  third  on  the  cuboid  bone. 

The  Peroneus  brevis  (extensor  tarsi  fibularis  brevier)  lies  beneath 
the  peroneus  longus ;  it  arises  from  the  lower  two-thirds  of  the  fibula, 
and  terminates  in  a  tendon  which  passes  behind  the  external  mal- 
leolus and  through  a  groove  in  the  os  calcis,  to  be  inserted  into  the 
base  of  tlic  metatarsal  bone  of  the  little  toe. 

Relations. — By  its  superficial  surface  with  the  peroneus  longus 
and  fascia  of  the  leg  and  foot.  By  its  deep  surface  with  the  fibula, 
the  OS  calcis,  and  cuboid  bone.  The  lateral  relations  are  the  same 
as  those  of  the  peroneus  longus.     The  tendon  of  the  peroneus  brevis 


MUSCLES  OF  THE  FOOT.  241 

has  but  two  tendinous  sheaths  and  two  synovial  membranes  ; — one 
behind  the  external  malleolus  and  common  to  both  peronei,  the  other 
upon  the  side  of  the  os  calcis. 

Actions. — The  peronei  muscles  are  extensors  of  the  foot,  con- 
jointly with  the  tibialis  posticus.  They  antagonise  the  tibialis  anticus 
and  peroneus  tertius,  which  are  flexors  of  the  foot.  The  whole  of 
these  muscles  acting  together,  tend  to  maintain  the  flatness  of  the 
foot,  so  necessary  to  security  in  walking. 

Foot. 

Dorsal  Region. 

Extensor  brevis  digitorum, 
Interossei  dorsales. 

The  Extensor  brevis  digitorum  muscle  arises  from  the  outer  side 
of  the  OS  calcis,  crosses  the  foot  obHquely,  and  terminates  in  four 
tendons,  the  innermost  of  which  is  inserted  into  the  base  of  the 
first  phalanx  of  the  great  toe,  and  the  other  three  into  the  sides  of 
the  long  extensor  tendons  of  the  second,  third,  and  fourth  toes. 

Relations. — By  its  upper  surface  with  the  tendons  of  the  extensor 
longus  digitorum,  peroneus  brevis,  and  with  the  deep  fascia  of  the 
foot.  By  its  under  surface  with  the  tarsal  and  metatarsal  bones. 
Its  inner  border  is  in  relation  with  the  dorsalis  pedis  artery,  and  the 
innermost  tendon  of  the  muscle  crosses  that  artery  just  before  its 
division. 

The  Dorsal  interossei  muscles  are  placed  between  the  metatarsal 
bones ;  they  resemble  the  analogous  muscles  in  the  hand  in  arising 
by  two  heads  from  the  adjacent  sides  of  the  metatarsal  bones  ;  their 
tendons  are  inserted  into  the  base  of  the  first  phalanx,  and  into  the 
digital  expansion  of  the  tendons  of  the  long  extensor. 

The  first  dorsal  interosseous  is  inserted  into  the  inner  side  of  the 
second  toe,  and  is  therefore  an  adductor ;  the  other  three  are  inserted 
into  the  outer  side  of  the  second,  third,  and  fourth  toes,  and  are  con- 
sequently abductors. 

Relations. — By  their  upper  surface  with  a  strong  fascia  which 
separates  them  from  the  extensor  tendons.  By  their  under  surface 
with  the  plantar  interossei.  Each  of  the  muscles  gives  passage  to 
a  small  artery  (posterior  perforating)  which  communicates  with  the 
external  plantar  artery.  And  between  the  heads  of  the  first  interos- 
seous muscle  the  communicating  artery  of  the  dorsahs  pedis  takes 
its  course. 

Plantar  Region. 
First  Layer. 

Abductor  polUcis, 
Abductor  minimi  digiti, 
Flexor  brevis  digitorum. 
31 


242 


3IUSCLES  OF  THE  SOLE  OF  THE  FOOT. 


Dissection. — The  sole  of  the  foot  is  best  dissected  by  caiTying  an 
incision  around  the  heel,  and  along  the  inner  and  outer  borders  of 
the  foot,  to  the  great  and  little  toes.  This  incision  should  divide  the 
integument  and  superficial  fascia,  and  both  together  should  be  dis- 
sected from  the  deep  fascia,  as  far  forward  as  the  base  of  the  pha- 
langes, where  they  may  be  removed  from  the  foot  altogether.  The 
deep  fascia  should  then  be  removed,  and  the  first  layer  of  muscles 
will  be  brought  into  view. 


Fig.  95.^ 


Fig.  96.t 


The  Abductor  pollicis  lies  along  the  inner  border  of  the  foot ;  it 
arises  by  two  heads,  between  which  the  tendons  of  the  long  flexors, 
arteries,  veins,  and  nerves  enter  the  sole  of  the  foot.  One  head 
arises  from  the  inner  tuberosity  of  the  os  calcis,  the  other  from  the 
internal  annular  ligament  and  plantar  fascia.  Insertion,  into  the 
base  of  the  first  phalanx  of  the  great  toe,  and  into  the  internal  sesa- 
moid bone. 


*  The  first  layer  of  muscles  in  the  sole  of  the  foot ;  this  layer  is  exposed  by  the  removal 
of  tlie  plantar  fascia,  1.  The  os  calcis.  2.  The  posterior  part  of  the  plantar  fascia 
divided  transversely.  3.  The  abductor  pollicis.  4.  The  abductor  minimi  digiti.  5. 
The  flexor  brevis  digitorum.  6.  The  tendon  of  the  flexor  longus  pollicis  muscle.  7,7. 
The  lumbricalcs.  On  the  second  and  third  toes,  the  tendons  of  the  flexor  longus  digi- 
torum  are  seen  passing  through  the  bifurcation  of  the  tendons  of  the  flexor  brevis 
digitorum. 

t  Tlie  tijird  and  a  i>art  of  the  second  layer  of  muscles  of  the  sole  of  the  foot.  1.  The 
divided  edge  of  the  pbintar  fascia.  2.  Tlio  musculus  accessorius.  3.  The  tendon  of 
the  flexor  longus  digitorum,  previously  to  its  division.  4.  The  tendon  of  the  flexor 
longus  pollicis.  5.  The  flexor  brevis  pollicis.  6.  Tlic  adductor  pollicis.  7.  The  flexor 
brevis  minimi  digiti.  8.  The  transversus  pedis.  !i.  Intcrossci  muscles,  plantar  and 
dorsal.  10.  A  convex  ridge  formed  by  the  tendon  of  the  peroneus  longus  muscle  in  its 
oblique  course  across  the  foot. 


MUSCLES  OF  THE  SOLE  OF  THE  FOOT.  243 

Relations. — By  its  superficial  surface  with  the  internal  portion  of 
the  plantar  fascia.  By  its  deep  surface  with  the  flexor  brevis  poUicis, 
musculus  accessorius,  tendons  of  the  flexor  longus  digitorum  and 
flexor  longus  pollicis,  tendons  of  the  tibialis  anticns  and  posticus, 
the  plantar  vessels  and  nerves  and  the  tarsal  bones.  On  its  outer 
border  with  the  flexor  bi'evis  digitorum,  from  which  it  is  separated 
by  a  vertical  septum  of  the  plantar  fascia. 

The  Abductor  minimi  digiti  lies  along  the  outer  border  of  the  foot. 
It  arises  from  the  outer  tuberosity  of  the  os  calcis,  and  from  the 
base  of  the  metatarsal  bone  of  the  little  toe,  and  is  inserted  into  the 
base  of  the  first  phalanx  of  the  little  toe. 

Relations. — By  its  superficial  surface  with  the  external  portion  of 
the  plantar  fascia.  By  its  deep  surface  with  the  musculus  acces- 
sorius, flexor  brevis  minimi  digiti,  with  the  tarsal  boneS;  and  with 
the  metatarsal  bone  of  the  little  toe.  By  its  inner  side  with  the 
flexor  brevis  digitorum,  from  which  it  is  separated  by  the  vertical 
septum  of  the  plantar  fascia. 

The  Flexor  brevis  digitorum  (perforatus)  is  placed  between  the 
two  preceding  muscles.  It  arises  from  the  under  surface  of  the  os 
calcis  and  plantar  fascia,  and  is  inserted  by  four  tendons  into  the 
base  of  the  second  phalanx  of  the  four  lesser  toes.  Each  tendon 
divides,  previously  to  its  insertion,  to  give  passage  to  the  tendon  of 
the  long  flexor ;  hence  its  cognomen  perforatus. 

Relations. — By  its  superficial  surface  with  the  plantar  fascia.  By 
its  deep  surface  with  a  thin  layer  of  fascia  which  separates  it  from 
the  musculus  accessorius,  tendons  of  the  flexor  longus  digitorum  and 
flexor  longus  pollicis,  and  plantar  vessels  and  nerves.  By  its  borders 
with  the  vertical  septa  of  the  plantar  fascia,  which  separate  the 
muscle,  on  the  one  side  from  the  abductor  pollicis,  and  on  the  other 
from  the  abductor  minimi  digiti. 

Second  Layer. 

Musculus  accessorius, 
Lumbricales. 

Dissection. — The  three  preceding  muscles  must  be  divided  from 
their  origin,  and  anteriorly  through  their  tendons,  and  removed,  in 
order  to  bring  into  view  the  second  layer. 

The  Musculus  accessorius  arises  by  two  slips  from  either  side  of 
the  under  surface  of  the  os  calcis ;  the  inner  slip  being  fleshy,  the 
outer  tendinous.  The  muscle  is  inserted  into  the  outer  side  of  the 
tendon  of  the  flexor  longus  digitorum. 

Relations. — By  its  superficial  surface  with  the  thi-ee  muscles  of 
the  superficial  layer,  from  which  it  is  separated  by  their  fascial 
sheaths,  and  with  the  external  plantar  vessels  and  nerves.  By  its 
deep  surface  with  the  under  surface  of  the  os  calcis  and  the  long 
calcaneo-cuboid  ligament. 

The  Lumbricales  (lumbricus,  an  earthworm)  are  four  little  muscles 
arising  from  the  tibial  side  of  the  tendons  of  the  flexor  longus  digi- 


244  MUSCLES  OF  THE  SOLE  OF  THE  FOOT. 

torum,  and  inserted  into  the  expansion  of  the  extensor  tendons,  and 
into  the  base  of  the  first  phalanx  of  the  four  lesser  toes. 

Relations. — By  their  superficial  surface  with  the  tendons  of  the 
flexor  longus  digitorum.  By  their  deep  surface  with  the  third  layer 
of  muscles  of  the  sole  of  the  foot.  They  pass  between  the  digital 
slips  of  the  deep  fascia  to  reach  their  insertion. 

Third  Layer. 

Flexor  brevis  poUicis, 
Adductor  poUicis, 
Flexor  brevis  minimi  digiti, 
Transversus  pedis. 

Dissection. — The  tendons  of  the  long  flexors  and  the  muscles  con- 
nected with  them  must  be  removed,  to  see  clearly  the  attachments  of 
the  third  layer. 

The  Flexor  hrevis  poUicis  arises  by  a  pointed  tendinous  process 
from  the  os  calcis,  the  side  of  the  cuboid,  and  from  the  external  and 
middle  cuneiform  bones ;  and  is  inserted  by  two  heads  into  the  base 
of  the  first  phalanx  of  the  great  toe.  Two  sesamoid  bones  are  de- 
veloped in  the  tendons  of  insertion  of  these  two  heads,  and  the  tendon 
of  the  flexor  longus  poUicis  lies  in  the  groove  between  them. 

Relations. — By  its  superficial  surface  with  the  abductor  pollicis, 
tendon  of  the  flexor  longus  pollicis,  and  plantar  fascia.  By  its  deep 
surface  with  the  tarsal  bones  and  their  ligaments,  the  metatarsal 
bone  of  the  great  toe,  and  the  insertion  of  the  tendon  of  the  peroneus 
longus.  By  its  inner  border  with  the  abductor  polhcis.  By  its  outer 
harder  with  the  adductor  pollicis. 

The  Adductor  pollicis  arises  from  the  cuboid  bone,  from  the  sheath 
of  the  tendon  of  the  peroneus  longus,  and  from  the  base  of  the  third 
and  fourth  metatarsal  bones.  It  is  inserted  into  the  base  of  the  first 
phalanx  of  the  great  toe. 

Relations. — By  its  superficial  surface  with  the  tendons  of  the  flexor 
longus  and  flexor  brevis  digitorum,  the  musculus  accessorius,  and 
lumbricales.  By  its  deep  surface  with  the  tarsal  bones  and  liga- 
ments, the  external  plantar  artery  and  veins,  the  interossei  muscles, 
tendon  of  the  peroneus  longus,  and  metatarsal  bone  of  the  great  toe. 
By  its  inner  border  with  the  flexor  brevis  pollicis. 

The  Flexor  brevis  minimi  digiti  arises  from  the  base  of  the  meta- 
tarsal bone  of  the  little  toe,  and  from  the  sheath  of  the  tendon  of  the 
peroneus  longus.  It  is  inserted  into  the  base  of  the  first  phalanx  of 
the  little  toe. 

Relations. — By  its  superficial  surface  with  the  tendons  of  the  flexor 
longus  and  flexor  brevis  digitorum,  the  fourth  lumbricalis,  abductor 
minimi  digiti,  and  plantar  fascia.  By  its  deep  surface  with  the 
plantar  interosseous  muscle  of  the  fourth  metatarsal  space,  and  the 
metatarsal  bone. 

The  Transversus  pedis  arises  by  fleshy  slips,  from  the  heads  of 
the  metatarsal  bones  of  the  four  lesser  toes.  Its  tendon  is  inserted 
into  the  base  of  the  first  phalanx  of  the  great  toe. 


ACTION  OF  MUSCLES  OF  THE  FOOT.  245 

Relations. — By  its  superficial  surface  with  the  tendons  of  the  flexor 
longus  and  flexor  brevis  digitorum,  and  the  kimbricales.  By  its 
deep  surface  with  the  interossei,  and  heads  of  the  metatarsal  bones. 

Fourth  Layer. 
Interossei  plantares. 

The  Plantar  interossei  muscles  are  three  in  number,  and  are 
placed  iLpon  rather  than  between  the  metatarsal  bones.  They  arise 
from  the  base  of  the  metatarsal  bones  of  the  three  outer  toes,  and 
are  inserted  into  the  inner  side  of  the  extensor  tendon  and  base  of 
the  first  phalanx  of  the  same  toes.  In  their  action  they  are  all 
adductors. 

Relations. — By  their  swperficicd  surface  with  the  dorsal  interossei 
and  the  metatarsal  bones.  By  their  deej)  surface  with  the  external 
plantar  artery  and  veins  with  their  branches,  the  adductor  pollicis, 
transversus  pedis,  and  flexor  minimi  digiti. 

Actions. — All  the  preceding  muscles  act  upon  the  toes ;  and  the 
movements  which  they  are  capable  of  executing  may  be  referred  to 
four  heads,  viz.  flexion,  extension,  adduction,  and  abduction.  In 
these  actions  they  are  grouped  in  the  following  manner : — 

Flexion.  Extension. 

Flexor  longus  digitorum,  Extensor  longus  digitorum, 

Flexor  brevis  digitorum.  Extensor  brevis  digitorum. 

Flexor  accessorius, 
Flexor  minimi  digiti. 

Adduction.  Abduction. 

•r  ,  .    (  one  dorsal,  Interossei,  three  dorsal, 

'  \  three  plantar.  Abductor  minimi  digiti. 

The  great  toe,  like  the  thumb  in  the  hand,  enjoys  an  independent 
action,  and  is  provided  with  distinct  muscles  to  perform  its  move- 
ments. These  movements  are  precisely  the  same  as  those  of  the 
other  toes,  viz. : 

Flexion.  Extension. 

Flexor  longus  pollicis.  Extensor  proprius  pollicis, 

Flexor  brevis  poUicis,  Extensor  brevis  digitorum. 

Adduction.  Abduction. 

Adductor  polhcis.  Abductor  pollicis. 

The  only  muscles  excluded  from  this  table  are  the  lumbricales, 
four  small  muscles,  which  from  their  attachments  to  the  tendons  of 
the  long  flexor,  appear  to  be  assistants  to  their  action ;  and  the 
transversus  pedis,  a  small  muscle  placed  transversely  in  the  foot 
across  the  heads  of  the  metatarsal  bones,  which  has  for  its  office 
the  drawing  together  of  the  toes. 


CHAPTER    IV. 


ON  THE  FASCIA. 


Fascia  (fascia,  a  bandage,)  is  the  name  assigned  to  laminae  of 
various  extent  and  thickness,  which  are  distributed  through  the  dif- 
ferent regions  of  the  body,  for  the  purpose  of  investing  or  protecting 
the  softer  and  more  dehcate  organs.  From  a  consideration  of  their 
structure,  these  fasciae  may  be  arranged  in  three  classes : — cellular 
fasciae,  cellulo-fibrous  fasciae,  and  tendino-fibrous  fasciae. 

The  cellular  fascia  is  best  illustrated  in  the  common  subcutaneous 
investment  of  the  entire  body,  the  superficial  fascia.  This  structure 
is  situated  immediately  beneath  the  integument  over  every  part  of 
the  frame,  and  is  the  medium  of  connexion  between  that  layer  and 
the  deeper  parts.  It  is  composed  of  cellular  tissue  containing  in  its 
areolae  a  considerable  abundance  of  adipose  vesicles.  The  fat,  being 
a  bad  conductor  of  caloric,  serves  to  retain  the  warmth  of  the  body; 
while  it  forms  at  the  same  time  a  yielding  tissue,  through  which  the 
minute  vessels  and  nerves  may  pass  to  the  papillary  layer  of  the 
skin,  without  incurring  the  risk  of  obstruction  from  injury  or  pres- 
sure upon  the  surface.  By  dissection,  the  superficial  fascia  may  be 
separated  into  two  layers,  between  which  are  found  the  superficial 
or  cutaneous  vessels  and  nerves ;  as,  the  superficial  epigastric  artery, 
the  saphenous  veins,  the  radial  and  ulnar  veins,  the  superficial 
lymphatic  vessels,  also  the  cutaneous  muscles,  as  the  platysma 
myoides,  orbicularis  palpebrarum,  sphincter  ani,  &c.  In  some  situ- 
ations where  the  deposition  of  fat  would  have  been  injurious  to  the 
functions  of  the  part,  the  cells  of  the  cellular  fascia  are  moistened 
by  a  serous  exhalation,  analogous  to  the  secretion  of  serous  mem- 
branes, as  in  the  eyelids  and  scrotum. 

The  cellulo-fLbrous  fascia  appears  to  result  from  a  simple  condens- 
ation of  cellular  tissue  deprived  of  its  fat,  and  intermingled  with 
strong  fibres  disposed  in  various  directions,  so  as  to  constitute  an 
inelastic  membrane  of  considerable  strength.  Of  this  structure  is 
the  deep  fascia  of  the  neck,  some  of  the  fasciae  of  the  cavities  of  the 
trunk,  as  the  thoracic  and  transversalis  fasciae,  and  the  sheaths  of 
vessels. 

The  tendino-fibrous  fascia  is  the  strongest  of  the  three  kinds  of 
investing  membrane ;  it  is  composed  of  strong  tendinous  fibres,  run- 
ning parallel  with  each  other,  and  connected  by  other  fibres  of  the 
same  kind  passing  in  diflferent  directions.  When  freshly  exposed, 
it  is  brilliant  and  nacreous,  and  is  tough,  inelastic,  and  unyielding. 
In  the  limbs  it  forms  the  deep  fascia,  enclosing  and  forming  distinct 


FASCIA  OF  THE  HEAD  AND  NECK.  247_ 

sheaths  to  all  the  muscles  and  tendons.  It  is  thick  upon  the  outer 
and  least  protected  side  of  the  limb,  and  thinner  upon  its  inner  side. 
It  is  firmly  connected  to  the  bones  and  to  the  prominent  points  of 
each  region,  as  to  the  pelvis,  knee,  and  ankle,  in  the  lower,  and  to 
the  clavicle,  scapula,  elbow,  and  wrist  in  the  upper  extremity.  It 
assists  the  muscles  in  their  action,  by  keeping  up  a  tonic  pressure 
on  their  surface  ;  aids  materially  in  the  circulation  of  the  fluids  in 
opposition  to  the  laM^s  of  gravity ;  and  in  the  palm  of  the  hand  and 
sole  of  the  foot  is  a  powerful  protection  to  the  structures  which  enter 
into  the  formation  of  these  regions.  In  some  situations  its  tension 
is  regulated  by  muscular  action,  as  by  the  tensor  vaginas  femoris 
and  gluteus  maximus  in  the  thigh,  by  the  biceps  in  the  leg,  and  by 
the  biceps  and  palmaris  longus  in  the  arm  ;  in  other  situations  it 
affords  an  extensive  surface  for  the  origin  of  the  fibres  of  muscles. 

The  fasciae  may  be  arranged  like  the  other  textures  of  the  body 
into — 1.  Those  of  the  head  and  neck.  2.  Those  of  the  trunk.  3. 
Those  of  the  upper  extremity.     4.  Those  of  the  lower  extremity. 


FASCIiE  OF  THE  HEAD  AND  NECK. 

The  temporal  fascia  is  a  strong  tendino-fibrous  membrane  which 
covers  in  the  temporal  muscle  at  each  side  of  the  head,  and  gives 
origin  by  its  internal  surface  to  the  superior  muscular  fibres.  It  is 
attached  to  the  whole  extent  of  the  temporal  ridge  above,  and  to 
the  zygomatic  arch  below ;  in  the  latter  situation  it  is  thick  and 
divided  into  two  layers,  the  external  being  connected  to  the  upper 
border  of  the  arch,  and  the  internal  to  its  inner  surface.  A  small 
quantity  of  fat  is  usually  found  between  these  two  layers,  together 
with  the  orbital  branch  of  the  temporal  artery. 

The  superficial  cervical  fascia  contains  between  its  layers  the 
platysma  myoides  muscle. 

The  deep  cervical  fascia  is  a  strong  cellulo-fibrous  layer  which 
invests  the  muscles  of  the  neck,  and  retains  and  supports  the  vessels 
and  nerves.  It  commences  posteriorly  at  the  ligamentum  nuchas, 
and  passes  forwards  at  each  side  beneath  the  trapezius  muscle  to 
the  posterior  border  of  the  sterno-mastoid  ;  here  it  divides  into  two 
layers  which  embrace  that  muscle  and  unite  upon  its  anterior  border 
to  be  prolonged  onwards  to  the  middle  line  of  the  neck,  where  it 
becomes  continuous  with  the  fascia  of  the  opposite  side.  Besides 
thus  constituting  a  sheath  for  the  sterno-mastoid,  it  also  forms  sheaths 
for  the  other  muscles  of  the  neck  over  which  it  passes.  If  the  super- 
ficial layer  of  the  sheath  of  the  sterno-mastoid  be  traced  upwards, 
it  will  be  found  to  pass  over  the  parotid  gland  and  masseter  muscle, 
and  to  be  inserted  into  the  zygomatic  arch;  and  if  it  be  traced 
downwards,  it  will  be  seen  to  pass  in  front  of  the  clavicle  and  be- 
come lost  upon  the  pectoralis  major  muscle.  If  the  deep  layer  of 
the  sheath  be  examined  superiorly,  it  will  be  found  attached  to  the 
styloid  process,  from  which  it  is  reflected  to  the  angle  of  the  lower 


248 


FASCIA  OF  THE  TRUNK. 


jaw, 


Fiff.  97* 


forming  the  stylo-maxillary  ligament;   and  if  it  be  followed 

downwards,  it  will  be  found  con- 
nected with  the  tendon  of  the  omo- 
hyoid muscle,  and  may  thence  be 
traced  behind  the  clavicle  where 
it  encloses  the  subclavius  muscle, 
and  being  extended  from  the  cai'- 
tilage  of  the  first  rib  to  the  cora- 
coid  process,  constitutes  the  costo- 
coracoid  membrane.  In  front  of 
the  sterno-mastoid  muscle,  the  deep 
fascia  is  attached  to  the  border  of 
the  lower  jaw  and  os  hyoides,  and 
forms  a  distinct  sheath  for  the  sub- 
maxillary gland.  Inferiorly  it  di- 
vides into  two  layers,  one  of  which 
passes  in  front  of  the  sternum,  while 
the  other  is  attached  to  its  superior 
border. 


FASCIA  OF  THE  TRUNK. 

The  thoracic  fasciaj  is  a  dense  layer  of  cellulo-fibrous  membrane 
stretched  horizontally  across  the  superior  opening  of  the  thorax.  It 
is  firmly  attached  to  the  concave  margin  of  the  first  rib,  and  to  the 
inner  surface  of  the  sternum.  In  front  it  leaves  an  opening  for  the 
connexion  of  the  cervical  with  the  thoracic  portion  of  the  thymus 
gland,  and  behind  it  forms  an  arch  across  the  vertebral  column,  to 
give  passage  to  the  oesophagus. 

At  the  point  where  the  great  vessels  and  trachea  pass  through  the 
thoracic  fascia,  it  divides  into  an  ascending  and  descending  layer. 
The  ascending  layer  is  attached  to  the  trachea,  and  becomes  con- 
tinuous with  the  sheath  of  the  carotid  vessels,  and  with  the  deep 
cervical  fascia ;  the  descending  layer  descends  upon  the  trachea  to 

*  A  transverse  section  of  the  neck,  showing  the  deep  cervical  fascia  and  its  numerous 
proloni,''ations,  forming  sheaths  for  the  different  muscles.  As  the  figure  is  symmetri- 
cal, the  figures  of  reference  are  placed  only  on  one  side.  1.  The  platysma  myoides. 
2.  Tlie  trapezius.  3.  The  ligamentum  nucha?,  from  which  the  fascia  may  be  traced 
forwards  beneath  the  trapezius,  enclosing  the  other  muscles  of  the  neck.  4.  The  point 
at  which  the  fascia  divides,  to  form  a  sheath  for  the  sterno-mastoid  muscle.  6.  The 
point  of  reunion  of  the  two  layers  of  the  sterno-mastoid  slieath.  7.  The  point  of  union 
of  the  dec])  cervical  fascia  of  opposite  sides  of  the  neck.  8.  Section  of  the  sterno-hyoid, 
9.  Omo-hyoid.  10.  Sterno-tiiyroid.  11.  The  lateral  lobe  of  the  thyroid  gland.  12. 
The  trachea.  1.3.  The  oesophagus.  14.  The  slieath  containing  the  common  carotid 
artery,  internal  jugular  vein,  and  pneumogastric  nerve.  1.5.  The  longus  colli.  The 
nerve  in  front  of  the  sheath  of  tliis  muscle  is  the  sympathetic.  16.  The  rectus  anticus 
major.  17.  Scalenus  anticus.  18.  Scalenus  posticus.  19.  The  splenius  capitis.  20. 
Splcnius  colli.  21.  Iiovator  anguli  scapulte.  22.  Complexus.  23.  Trachelo-mastoid. 
24.  Transversalis  colli.  2.5.  Cerviealis  ascendcns.  2(i.  The  semi-spinalis  colli.  27. 
The  multifidus  spiniE.  28.  A  cervical  vertebra.  Tlie  transverse  processes  are  seen  to 
be  traversed  by  the  vertebral  artery  and  vein. 

t  For  an  excellent  description  of  this  fascia,  see  Sir  Astley  Cooper's  work  on  the 
"  Anatomy  of  the  Thymus  Gland." 


ABDOMINAL  FASCIA.  249 

its  bifurcation,  surrounds  the  large  vessels  arising  from  the  arch  of 
the  aorta,  and  the  upper  part  of  the  arch  itself,  and  is  continuous 
with  the  fibrous  layer  of  the  pericardium.  It  is  connected  also  with 
the  vense  innominatse  and  superior  cava,  and  is  attached  to  the 
cellular  capsule  of  the  thymus  gland. 

"  The  thoracic  fascia,"  writes  Sir  Astley  Cooper,  "  performs  three 
important  offices : — ■ 

"  1st.  It  forms  the  upper  boundary  of  the  chest,  as  the  diaphragm 
does  the  lower. 

"  2nd.  It  steadily  preserves  the  relative  situation  of  the  parts 
which  enter  and  quit  the  thoracic  opening. 

"  3d.  It  attaches  and  supports  the  heart  in  its  situation,  through 
the  medium  of  its  connexion  with  the  aorta  and  large  vessels  which 
are  placed  at  its  curvature." 

ABDOMINAL  FASCIA. 

The  lower  part  of  the  parietes  of  the  abdomen,  and  the  cavity  of  the 
pelvis,  are  strengthened  by  a  layer  of  fascia  which  lines  their  inter- 
nal surface,  and  at  the  bottom  of  the  latter  cavity  is  reflected  in- 
wards to  the  sides  of  the  bladder.  This  fascia  is  continuous  through- 
out the  whole  of  the  surface ;  but  for  convenience  of  description  it 
is  considered  under  the  several  names  of  transversalis  fascia,  iliac 
fascia,  and  pelvic  fascia ;  the  two  former  meet  at  the  crest  of  the 
ilium,  and  Poupart's  ligament,  and  the  latter  is  confined  to  the  cavity 
of  the  true  pelvis. 

The  fascia  transversalis  (Fascia  Cooperi)*  is  a  cellulo-fibrous 
lamella  which  lines  the  inner  surface  of  the  transversalis  muscle. 
It  is  thick  and  dense  below,  near  the  lower  part  of  the  abdomen; 
but  becomes  thinner  as  it  ascends,  and  is  gradually  lost  in  the  sub- 
serous cellular  tissue.  It  is  attached  inferiorly  to  the  reflected  margin 
of  Poupart's  ligament  and  to  the  crest  of  the  ilium  ;  internally,  to 
the  border  of  the  rectus  muscle ;  and  at  the  inner  third  of  the  femoral 
arch,  is  continued  beneath  Poupart's  ligament,  and  forms  the  ante- 
rior segment  of  the  crural  canal,  or  sheath  of  the  femoral  vessels. 

The  internal  abdominal  ring  is  situated  in  this  fascia,  at  about 
midway  between  the  spine  of  the  os  pubis,  and  the  anterior  superior 
spine  of  the  ilium,  and  half  an  inch  above  Poupart's  ligament ;  it  is 
bounded  upon  its  inner  side  by  a  well-marked  falciform  border,  but 
is  ill  defined  around  its  outer  margin.  From  the  circumference  of 
this  ring  is  given  off"  an  infundibiUform  process  which  surrounds  the 
testicle  and  spermatic  cord,  constituting  the  fascia  propria  of  the 
latter,  and  forms  the  first  investment  to  the  sac  of  oblique  inguinal 
hernia.  It  is  the  strength  of  this  fascia,  in  the  interval  between  the 
head  of  the  rectus  and  the  internal  abdominal  ring,  that  defends  this 

*  Sir  Astley  Cooper  first  described  this  fascia  in  its  important  relation  to  inguinal 
hernia. 

32 


250  INGUINAL  HERNIA. 

portion  of  the  parietes  from  the  frequent  occurrence  of  direct  in- 
guinal hernia. 

INGUINAL  HERNIA. 

Ino-Liinal  hernia  is  of  two  kinds,  obUque,  and  direct. 

In  obUque  inguinal  hernia  the  intestine  escapes  from  the  cavity 
of  the  abdomen  into  the  spermatic  canal,  through  the  internal  abdo- 
minal ring,  pressing  before  it  a  pouch  of  peritoneum  which  consti- 
tutes the  hernial  sac,  and  distending  the  infundibiliform  process  of 
the  transversalis  fascia.  After  emerging  through  the  internal  abdo- 
minal ring,  it  passes  frst  beneath  the  lower  and  arched  border  of 
the  transversalis  muscle ;  then  beneath  the  lower  border  of  the  in- 
ternal oblique  muscle ;  and  finally  through  the  external  abdominal 
rino-  in  the  aponeurosis  of  the  external  oblique.  From  the  trans- 
versalis muscle  it  receives  no  investment ;  while  passing  beneath  the 
lower  border  of  the  internal  oblique  it  obtains  the  cremaster  muscle ; 
and,  upon  escaping  at  the  external  abdominal  ring,  receives  the  in- 
tercolumnar  fascia.  So  that  the  coverings  of  an  oblique  inguinal 
hernia,  after  it  has  emerged  through  the  external  abdominal  ring, 
are,  from  the  surface  to  the  intestine,  the 

Integument, 

Superficial  fascia, 

Intercolumnar  fascia, 

Cremaster  muscle, 

Transversalis,  or  infundibiliform  fascia, 

Peritoneal  sac. 

The  spermatic  canal,  which,  in  the  normal  condition  of  the  abdo- 
minal parietes  serves  for  the  passage  of  the  spermatic  cord  in  the 
male,  and  the  round  hgament  with  its  vessels  in  the  female,  is  about 
one  inch  and  a  half  in  length.  It  is  bounded  in  front  by  the  aponeu- 
rosis of  the  external  oblique  muscle ;  heliind  by  the  transversalis 
fascia,  and  by  the  conjoined  tendon  of  the  internal  oblique  and  trans- 
versahs  muscle ;  above  by  the  arched  borders  of  the  internal  oblique 
and  transversalis ;  below  by  the  grooved  border  of  Poupart's  liga- 
ment; and  at  each  extremity  by  one  of  the  abdominal  rings,  the  in- 
ternal ring  at  the  inner  termination,  the  external  ring  at  the  outer 
extremity.  These  relations  may  be  more  distinctly  illustrated  by 
the  following  plan — 

Above. 
Lower  borders  of  internal  oblique 
and  transversalis  muscle. 
In  Front.  Behind. 

Transversalis  fascia.  Con- 
joined lendon  of  internal 
oblique  and  transversalis. 


Aponeurosis  of  external  Spermatic  canal. 

oblique.  * 


Below. 
Grooved  border  of 
Poupart's  ligament, 


DIRECT  INGUINAL  HERNIA.  251 

There  are  three  varieties  of  oblique  inguinal  hernia : — common, 
congenita],  and  encysted. 

Common  oblique  hernia  is  that  which  has  been  described  above. 

Congenital  hernia  results  from  the  nonclosure  of  the  pouch  of  peri- 
toneum carried  downwards  into  the  scrotum  by  the  testicle,  during 
its  descent  in  the  foetus. 

The  intestine  at  some  period  of  life  is  forced  into  this  canal,  and 
descends  through  it  into  the  tunica  vaginalis  where  it  lies  in  contact 
with  the  testicle ;  so  that  congenital  hernia  has  no  proper  sac,  but  is 
contained  within  the  tunica  vaginalis.  The  other  coverings  are  the 
same  as  those  of  common  inguinal  hernia. 

Encysted  heniia  (hernia  infantihs,  of  Hey)  is  that  form  of  pro- 
trusion in  which  the  pouch  of  peritoneum  forming  the  tunica  vagi- 
nalis, being  only  partially  closed,  and  remaining  open  externally  to 
the  abdomen,  admits  of  the  hernia  passing  into  the  scrotum,  behind 
the  tunica  vaginalis.  So  that  the  surgeon  in  operating  upon  this 
variety,  requires  to  divide  three  layers  of  serous  membrane ;  the  first 
and  second  layers  being  those  of  the  tunica  vaginalis ;  and  the  third, 
the  true  sac  of  the  hernia. 

Direct  inguinal  hernia*  has  received  its  name  from  passing  directly 
through  the  external  abdominal  ring,  and  forcing  before  it  the 
opposing  parietes.  This  portion  of  the  wall  of  the  abdomen  is 
strengthened  by  the  conjoined  tendon  of  the  internal  oblique  and 
transversalis  muscle,  which  is  pressed  before  the  hernia,  and  forms 
one  of  its  investments.     Its  coverings  are,  the 

Integument, 
Superficial  fascia, 
Intercolumnar  fascia, 
Conjoined  tendon, 
Transversalis  fascia. 
Peritoneal  sac.    • 

Direct  inguinal  hernia  differs  from  oblique  in  never  attaining  the 
same  bulk,  in  consequence  of  the  resisting  nature  of  the  conjoined 
tendon  of  the  internal  oblique  and  transversalis  and  of  the  transver- 
salis fascia ;  in  its  direction,  having  a  tendency  to  protrude  from  the 
middle  line  rather  than  towards  it.  Thirdly,  in  making  for  itself  a 
new  passage  through  the  abdominal  parietes,  instead  of  following  a 
natural  channel ;  and  fourthly,  in  the  relation  of  the  neck  of  its  sac 
to  the  epigastric  artery ;  that  vessel  lying  to  the  outer  side  of  the 
opening  of  the  sac  of  direct  hernia,  and  to  the  inner  side  of  oblique 
hernia. 

All  the  forms  of  inguinal  hernia  are  designated  scrotal,  when  they 
have  descended  into  that  cavity. 

The  fascia  iliaca  is  the  tendino-fibrous  investment  of  the  psoas 
and  iliacus  muscles ;  and,  hke  the  fascia  transversalis,  is  thick 
below,  and  becomes  gradually  thinner  as  it  ascends.  It  is  attached 
superiorly  along  the  edge  of  the  psoas,  to  the  anterior  lamella  of  the 

*  Known  in  America  by  the  name  ventro-inguinal  hernia. — G. 


252 


PELVIC  LAYEK   OK   FASCIA. 


aponeurosis  of  the  transversalis  muscle,  to  the  ligamentum  arcuatum 
internum,  and  to  the  bodies  of  the  kimbar  vertebrae,  leaving  arches 
corresponding  with  the  constricted  portions  of  the  vertebrae  for  the 
passage  of  the  lumbar  vessels.  Lower  down  it  passes  beneath  the 
external  iliac  vessels,  and  is  attached  along  the  margin  of  the  true 
pelvis ;  externally,  it  is  connected  to  the  crest  of  the  ilium ;  and,  infe- 
riorly,  to  the  outer  two-thirds  of  Poupart's  ligament,  where  it  is  con- 
tinuous with  the  fascia  transversalis.  Passing  beneath  Poupart's 
hgament,  it  surrounds  the  psoas  and  iliacus  muscles  to  their  termi- 
nation, and  beneath  the  inner  third  of  the  femoral  arch  forms  the 
posterior  segment  of  the  sheath  of  the  femoral  vessels. 

The  fascia  pelvica  is  attached  to  the  inner  surface  of  the  os  pubis 
and  along  the  margin  of  the  brim  of  the  pelvis,  where  it  is  continu- 
ous with  the  iliac  fascia.  From  this  extensive  origin  it  descends 
into  the  pelvis,  and  divides  into  two  layers,  the  pelvic  and  obturator. 

Fig.  98.* 


The  pelvic  layer  or  fascia,  when  traced  from  the  internal  surface 
of  the  OS  pubis  near  to  the  symphysis,  is  seen  to  be  reflected  inwards 
to  the  neck  of  the  bladder,  so  as  to  form  the  anterior  vesical  liga- 
ments. Traced  backwards,  it  passes  between  the  sacral  plexus  of 
nerves  and  the  internal  iliac  vessels,  and  is  attached  to  the  anterior 
surface  of  the  sacrum ;  and  followed  from  the  sides  of  the  pelvis,  it 
descends  to  the  base  of  the  bladder  and  divides  into  three  layers, 
one  ascending,  is  reflected  to  the  side  of  that  viscus,  encloses  the 

*  A  transverse  section  of  the  pelvis,  showing  the  distribution  of  the  pelvic  fascia.  1. 
The  bladder.  2.  The  vesiculse  seminales  divided  across.  3.  The  rectum.  4.  The 
iliac  fascia  coverin/j  in  the  iliacus  and  psoas  muscles  (5) ;  and  forming  a  sheath  for  the 
external  iliac  vessels  (6).  7.  The  anterior  crural  nerve  excluded  from  the  sheath.  8. 
The  pelvic  fascia.  9.  Its  ascending  layer,  forming  the  lateral  ligament  of  the  bladder 
of  one  side,  and  a  sheath  to  the  vesical  plexus  of  veins.  10.  The  recto-vesical  fascia 
of  Mr.  Tyrrell  formed  by  the  middle  layer.  11.  The  inferior  layer  surrounding  the 
rectum  and  meeting  at  the  middle  line  with  the  fascia  of  the  opposite  side.  12.  The 
levator  arii  muscle.  13.  The  obturator  intcrnus  muscle,  covered  in  by  the  obturator 
fascia,  which  also  forms  a  sheath  for  the  internal  pudic  vessels  and  nerve  (14).  15. 
The  layer  cf  fascia  which  invests  the  under  surface  of  the  levator  ani  muscle,  the  anal 
faBcia. 


OBTURATOR  FASCIA— rPERINEAL  FASCIA. 


253 


vesical  plexus  of  veins,  and  forms  the  lateral  ligaments  of  the  blad- 
der. A  middle  layer  passes  inwards  betv/een  the  base  of  the  blad- 
der and  the  upper  surface  of  the  rectum,  and  is  named  by  Mr.  Tyr- 
rell the  recto-vesical  fascia;  and  an  inferioi^  layer  passes  behind  the 
rectum,  and,  with  the  layer  of  the  opposite  side,  completely  invests 
that  intestine. 

The  obturator  fascia  passes  directly  downwards  from  the  splitting 
of  the  layers  of  the  pelvic  fascia,  and  covers  in  the  obturator  inter- 
nus  muscle  and  the  internal  pudic  vessels  and  nerve ;  it  is  attached 
to  the  ramus  of  the  os  pubis  and  ischium  in  front,  and  below  to  the 
falciform  margin  of  the  great  sacro-ischiatic  ligament.  Lying  be- 
tween these  two  layers  of  fascia  is  the  levator  ani  muscle,  which 
arises  from  their  angle  of  separation.  The  levator  ani  is  covered  in 
inferiorly  by  a  third  layer  of  fascia,  wliich  is  given  off  by  the  obtu- 
rator fascia,  and  is  continued  downwards  upon  the  inferior  surface 
of  the  muscle  to  the  extremity  of  the  rectum,  where  it  is  lost.  This 
layer  may  be  named  from  its  position  and  inferior  attachment  the 
anal  fascia. 

Fig.  99.* 


In  the  perineum  there  are  two  fascias  of  much  importance,  the 
superficial  and  deep  perineal  fascia. 

The  superficial  perineal  fascia  is  a  thin  tendino-fibrous  layer,  which 
covers  in  the  muscles  of  the  genital  portion  of  the  perineum  and  the 
root  of  the  penis.     It  is  firmly  attached  at  each  side  to  the  ramus  of 


*  The  pubic  arch  with  the  attachments  of  the  perineal  fascice.  1,  1,  1.  The  superfi- 
cial fascia  divided  by  a  V  shaped  incision  into  three  flaps  ;  the  lateral  flaps  are  turned 
over  the  ramus  of  the  os  pubis  and  ischium  at  each  side,  to  which  they  are  firmly 
attached ;  the  posterior  flap  is  continuous  with  the  deep  perineal  fascia.  2.  The  deep 
perineal  fascia.  3.  The  opening-  for  the  passage  of  the  membranous  portion  of  the 
urethra,  previously  to  entering  the  bulb.  4.  Two  projections  of  the  anterior  layer  of 
the  deep  perineal  fascia,  corresponding  with  Cowper's  glands. 


254 


DEEP  PERINEAL  FASCIA. 


the  OS  pubis  and  ischiam ;  posteriorly  it  is  reflected  backwards  be- 
neath the  transversus  perinei  muscles  to  become  connected  with  the 
deep  perineal  fascia ;  while  anteriorly  it  is  continuous  with  the  dartos 
of  the  scrotum. 


The  deep  perineal  fascia  (Camper's  ligament,  triangular  liga- 
ment) is  situated  behind  the  root  of  the  penis,  and  is  firmly  stretched 
across  between  the  ramus  of  the  os  pubis  and  ischium  of  each  side 
so  as  to  constitute  a  strong  septum  of  defence  to  the  outlet  of  the 
pelvis.  At  its  inferior  border  it  divides  into  two  layers,  one  of  which 
is  continued  forwards,  and  is  continuous  with  the  superficial  perineal 
fascia ;  while  the  other  is  prolonged  backwards  to  the  rectum,  and 
joining  with  the  anal  fascia  assists  in  supporting  the  extremity  of 
that  intestine.  The  deep  perineal  fascia  is  composed  of  two  layers, 
which  are  separated  from  each  other  by  several  important  parts, 
and  traversed  by  the  membranous  portion  of  the  urethra.     The  ante- 

*  A  side  view  of  the  viscera  of  the  pelvis,  showing  the  distribution  of  the  perineal 
and  pelvic  fascite.  1.  The  symphysis  pubis.  2.  The  bladder.  3.  The  recto-vesical 
fold  of  peritoneum,  passing-  from  the  anterior  surface  of  the  rectum  to  the  posterior  part 
of  the  bladder ;  from  the  upper  part  of  the  fundus  of  the  bladder  it  is  reflected  upon 
the  abdominal  parietes.  4.  The  ureter.  5.  The  vas  deferens  crossing-  the  direction  of 
the  ureter.  6.  The  vesicula  scminalis  of  the  right  side.  7,  7.  The  prostate  gland 
divided  by  a  longitudinal  section.  8,  8.  The  section  of  a  ring  of  clastic  tissue  encir- 
cling the  prostatic  portion  of  the  urethra  at  its  commencement.  9.  TJie  prostatic  por- 
tion of  the  urethra.  10.  The  membranous  portion,  enclosed  by  the  compressor  urethra; 
muscle.  11.  The  commencement  of  the  corpus  spongiosum  penis,  the  bulb.  12.  The 
anterior  ligaments  of  the  bladder  formed  liy  the  reflection  of  the  pelvic  fascia,  from  the 
internal  surface  of  the  os  pubis  to  tlic  neck  of  the  bladder.  13.  Tiie  edge  of  the  pelvic 
fascia  at  the  point  where  it  is  reflected  upon  the  rectum.  H.  An  interval  between  the 
pelvic  fascia  and  deep  perineal  fascia,  occupied  by  a  plexus  of  veins.  15.  The  deep 
perineal  fascia;  its  two  layers.  16.  Cowpcr's  gland  of  the  right  side  situated  between 
the  two  layers  below  the  membranous  portion  of  tlie  urethra.  17.  The  superficial 
perineal  fascia  ascending  in  front  of  tlic  root  of  the  penis  to  become  continuous  with 
the  dartos  of  tlie  scrotum  (18).  19.  The  layer  of  the  deep  fascia  which  is  prolonged 
to  the  rectum.  20.  Tlie  lower  part  of  the  levator  ani ;  its  fibres  arc  concealed  by  the 
anal  fascia.  21.  The  inferior  segment  of  the  fimncl-shapcd  process  given  off"  from  the 
posterior  layer  of  the  deep  perineal  fascia,  whieii  is  continuous  with  the  recto-vcsical 
fiiKcia  of  Tyrrell.  The  attachment  of  this  fascia  to  the  recto-vcsical  fold  of  peritoneum 
is  seen  at  22. 


PASCIiE  OF  THE  UPPER  EXTREMITY.  255 

rior  layer  is  nearly  plane  in  its  direction,  and  sends  a  sheath  for- 
wards around  the  anterior  termination  of  the  membranous  urethra 
to  be  attached  to  the  posterior  part  of  the  bulb.  The  posterior  layer 
is  oblique  and  sends  a  funnel-shaped  process  backwards,  which 
invests  the  commencement  of  the  membranous  urethra  and  the  pro- 
state gland.  The  inferior  segment  of  this  funnel-shaped  process  is 
continued  backwards  beneath  the  prostate  gland  and  the  vesiculoB 
seminales,  and  is  continuous  with  the  recto-vesical  fascia  of  Tyrrell, 
which  is  attached  posteriorly  to  the  recto-vesical  fold  of  peritoneum, 
and  serves  the  important  oifice  of  retaining  that  duplicature  in  its 
proper  situation. 

Between  the  two  layers  of  the  deep  perineal  fascia  are  situated, 
therefore,  the  whole  extent  of  the  membranous  portion  of  the  urethra, 
the  compressor  urethra  muscle,  Cowper's  glands,  the  internal  pudic 
and  bulbous  arteries,  and  a  plexus  of  veins.  Mr.  Tyrrell  considers 
the  anterior  lamella  alone  as  the  deep  perineal  fascia,  and  the  pos- 
terior lamella  as  a  distinct  layer  of  fascia  covering  in  a  considerable 
plexus  of  veins. 

FASCIiE  OF  THE  UPPER  EXTREMITY. 

The  superficial  fascia  of  the  upper  extremity  contains  between 
its  layers  the  superficial  veins  and  lymphatics,  and  the  superficial 
nerves. 

The  deep  fascia  is  thin  over  the  deltoid  and  pectoralis  major 
muscles,  and  in  the  axillary  space,  but  thick  upon  the  dorsum  of  the 
scapula,  where  it  binds  down  the  infra-spinatus  muscle.  It  is  at- 
tached to  the  clavicle,  acromion  process,  and  spine  of  the  scapula. 
In  the  upper  arm  it  is  somewhat  stronger,  and  is  inserted  into  the 
condyloid  ridges,  forming  the  intermuscular  septa.  In  the  fore-arm 
it  is  very  strong,  and  at  the  bend  of  the  elbow  its  thickness  is  aug- 
mented by  a  broad  band,  which  is  given  off  from  the  inner  side  of 
the  tendon  of  the  biceps.  It  is  firmly  attached  to  the  olecranon 
process,  to  the  ulna,  and  to  the  prominent  points  about  the  wrist. 
Upon  the  front  of  the  wrist  it  is  continuous  with  the  anterior  annular 
ligament,  which  is  considered  by  some  anatomists  to  be  formed  by 
the  deep  fascia,  but  which  I  am  more  disposed  to  regard  as  a  liga- 
ment of  the  wrist.  On  the  posterior  aspect  of  this  joint  it  forms  a 
strong  transverse  band,  the  fosterior  annular  ligament,  beneath  which 
the  tendons  of  the  extensor  muscles  pass,  in  distinct  sheaths. 

The  tendons  as  they  pass  beneath  the  annular  ligaments  are 
surrounded  by  synovial  bursse.  The  dorsum  of  the  hand  is  invested 
by  a  thin  fascia,  which  is  continuous  with  the  posterior  annular 
ligament. 

The  palmar  fascia  is  divided  into  three  portions.  A  central  por- 
tion, which  occupies  the  middle  of  the  palm,  and  two  lateral  por- 
tions, which  spread  out  over  the  sides  of  the  hand,  and  are  continuous 
with  the  dorsal  fascia.  The  central  portion  is  strong  and  tendinous : 
it  is  narrow  at  the  wrist,  where  it  is  attached  to  the  annular  liga- 


256  FASCI-E  OF  THE  LOWER  EXTREMITY. 

ment,  and  broad  over  the  heads  of  the  metacarpal  bones,  where  it 
divides  into  eight  slips,  which  are  inserted  into  the  sides  of  the  bases 
of  the  phalanges  of  each  finger.  The  fascia  is  strengthened  at  its 
point  of  division  into  slips  by  strong  fasciculi  of  transverse  fibres. 
and  the  arched  interval  left  between  the  slips  gives  passage  to  the 
tendons  of  the  flexor  muscles.  The  arches  between  the  finsrers 
transmit  the  digital  vessels  and  nerves,  and  lumbricales  muscles. 

FASCIA  OF  THE  LOWER  EXTREMITY. 

The  superficial  fascia  contains  between  its  two  layers  the  super- 
ficial vessels  and  nerves  of  the  lower  extremity.  At  the  groin  these 
two  layers  are  separated  from  each  other  by  the  superficial  lymphatic 
glands,  and  the  deeper  layer  is  attached  to  Poupart's  ligament, 
while  the  superficial  layer  is  continuous  with  the  superficial  fascia 
of  the  abdomen. 

The  deep  fascia  of  the  thigh  is  named,  from  its  great  extent,  the 
fascia  lata ;  it  is  thick  and  strong  upon  the  outer  side  of  the  limb, 
and  thinner  upon  its  inner  and  posterior  side.  That  portion  of  fascia 
which  invests  the  gluteus  maximus  is  very  thin,  but  that  which  covers 
in  the  gluteus  medius  is  excessively  thick,  and  gives  origin,  by  its 
inner  surface,  to  the  superficial  fibres  of  that  muscle.  The  fascia 
lata  is  attached  superiorly  to  Poupart's  ligament,  the  crest  of  the 
ilium,  sacrum,  coccyx,  tuberosity  of  the  ischium,  ramus  of  the 
ischium  and  os  pubis  and  body  of  the  os  pubis ;  in  the  thigh  it  is 
inserted  into  the  linea  aspera,  and  around  the  knee  is  connected  with 
the  prominent  points  of  that  joint.  It  possesses  also  two  muscular 
attachments, — by  means  of  the  tensor  vaginae  femoris,  which  is 
inserted  between  its  two  layers  on  the  outer  side,  and  the  gluteus 
maximus  which  is  attached  to  it  behind. 

In  addition  to  the  smaller  openings  in  the  fascia  lata  which  trans- 
mit the  small  cutaneous  vessels  and  nerves,  there  exists  at  the  upper 
and  inner  extremity  of  the  thigh  an  obUque  foramen,  which  gives 
passage  to  the  superficial  lymphatic  vessels,  and  the  large  subcu- 
taneous vein  of  the  lower  extremity,  the  internal  saphenous  vein,  and 
is  thence  named  the  saphenous  opening.  The  existence  of  this 
opening  has  given  rise  to  the  division  of  the  upper  part  of  the  fascia 
lata  into  two  portions,  an  iliac  portion  and  a  pubic  portion. 

The  iliac  portion  is  situated  upon  the  iliac  side  of  the  opening. 
It  is  attached  to  the  crest  of  the  ilium,  and  along  Poupart's  ligament 
to  the  spine  of  the  os  pubis,  whence  it  is  reflected  downwards  and 
outwards  in  an  arched  direction,  and  forms  a  falciform  border,  which 
constitutes  the  outer  boundary  of  the  say)hcnous  opening.  The  edge 
of  this  border  immediately  overlies,  and  is  reflected  upon,  the  sheath 
of  the  femoral  vessels,  and  the  lower  extremity  of  the  curve  is  con- 
tinuous with  the  pubic  portion. 

The  pubic  portion,  occupying  the  pubic  side  of  the  saphenous 
opening,  is  attached  to  the  spine  of  the  os  pubis  and  pectineal  line ; 
and,  passing  outvv^ards  behind  the  sheath  of  the  femoral  vessels, 


FASCIA  LATA FEMORAL  RING.  257 

divides  into  two  layers ;  the  anterior  layer  is  continuous  with  that 
portion  of  the  iliac  fascia  which  forms  the  sheath  of  the  iliacus  and 
psoas  muscles,  and  the  posterior  layer  is  lost  upon  the  capsule  of 
the  hip-joint. 

The  interval  between  the  falciform  border  of  the  iliac  portion  and 
the  opposite  surface  of  the  pubic  portion  is  closed  by  a  fibrous  layer, 
which  is  pierced  by  numerous  openings  for  the  passage  of  lymphatic 
vessels,  and  is  thence  named  cribrifoi-m  fascia.  The  cribriform 
fascia  is  connected  with  the  sheath  of  the  femoral  vessels,  and  forms 
one  of  the  coverings  of  femoral  hernia.  When  the  iliac  portion  of 
the  fascia  lata  is  removed  from  its  attachment  to  Poupart's  ligament 
and  is  turned  aside,  the  sheath  of  the  femoral  vessels  (the  femoral 
or  crural  canal)  is  brought  into  view  ;  and  if  Poupart's  Ugament  be 

Fig.  101.* 


carefully  divided,  the  sheath  may  be  isolated,  and  its  continuation 
with  the  transversahs  and  iliac  fascia  clearly  demonstrated.  In  this 
view  the  sheath  of  the  femoral  vessels  is  an  infundibiliform  continua- 
tion of  the  abdominal  fasciae,  closely  adherent  to  the  vessels,  a  little 
way  down  the  thigh,  but  much  larger  than  the  vessels  it  contains  at 

*  A  section  of  the  structures  wiiich  pass  beneath  the  femoral  arch.  1.  Poupart's 
ligament.  2,  2.  The  iliac  portion  of  the  fascia  lata,  attached  along  the  margin  of  the 
crest  of  the  ilium,  and  along  Poupart's  ligament,  as  far  as  the  spine  of  the  os  pubis  (3). 
4.  The  pubic  portion  of  the  fascia  lata,  continuous  at  3  with  the  iliac  portion,  and  pass- 
ing outwards  behind  the  sheath  of  the  femoral  vessels  to  its  outer  border  at  5,  where  it 
divides  into  two  layers  ;  one  is  continuous  with  the  sheath  of  the  psoas  (6)  and  iliacus 
(7);  the  other  (8)  is  lost  upon  the  capsule  of  the  hip-joint  (9).  10.  The  femoral  nerve, 
enclosed  in  the  sheath  of  the  psoas  and  iliacus.  11.  Gimbernat's  ligament.  12.  The 
femoral  ring,  within  the  femoral  sheath.  13.  The  femoral  vein.  14.  The  femoral 
artery:  the  two  vessels  and  the  ring  are  surrounded  by  the  femoral  sheath,  and  thin 
septa  are  sent  between  the  anterior  and  posterior  wall  of  the  sheath,  dividing  the  artery 
from  the  vein,  and  the  vein  from  the  femoral  ring. 

33 


258  FEMORAL  HERNIA. 

Poupart's  ligament.     If  the  sheath  be  opened,  the  artery  and  vein 

will  be  found  lying  side  by  side,  and  occupying  the  outer  two-thirds 
of  the  sheath,  leaving  an  infundibiliform  interval  between  the  vein 
and  the  inner  wall  of  the  sheath.  The  superior  opening  of  this 
space  is-  named  X\\e  femoral  ring;  it  is  bounded  in  front  by  Poupart's 
lio-ament,  behind  by  the  os  pubis,  internally  by  Gimbernat's  ligament, 
and  externally  by  the  femoral  vein.  The  interval  itself  serves  for 
the  passage  of  the  superficial  lymphatic  vessels  from  the  saphenous 
opening  to  a  lymphatic  gland,  which  generally  occupies  the  femoral 
rino- ;  and  from  thence  they  proceed  into  the  current  of  the  deep 
lymphatics.  The  femoral  ring  is  closed  merely  by  a  thin  layer  of 
subserous  cellular  tissue,*  which  retains  the  lymphatic  gland  in  its 
position,  and  is  named  septum  crurale ;  and  by  the  peritoneum.  It 
follows  from  this  description,  that  the  femoral  ring  must  be  a  weak 
point  in  the  parietes  of  the  abdomen,  particularly  in  the  female, 
where  the  femoral  arch,  or  space  included  between  Poupart's  liga- 
ment and  the  border  of  the  pelvis,  is  larger  than  in  the  male,  while 
the  structures  which  pass  through  it  are  smaller.  It  happens  con- 
sequently, that  if  violent  or  continued  pressure  be  made  upon  the 
abdominal  viscera,  a  portion  of  intestine  may  be  forced  through  the 
femoral  ring  into  the  infundibiliform  space  in  the  sheath  of  the 
femoral  vessels,  carrying  before  it  the  peritoneum  and  the  septum 
crurale, — this  constitutes  femoral  hernia.  If  the  causes  which  give 
rise  to  the  formation  of  this  hernia  continue,  the  intestine,  unable  to 
extend  further  down  the  sheath,  from  its  close  connexion  to  the  ves- 
sels, will  in  the  next  place  be  forced  forwards  through  the  saphenous 
opening  in  the  fascia  lata,  carrying  before  it  two  additional  cover- 
ings, the  sheath  of  the  vessels,  or  fascia  propria,  and  the  cribriform 
fascia,  and  then  curving  upwards  over  Poupart's  ligament,  will 
become  placed  beneath  the  superficial  fascia  and  integument. 

The  direction  which  femoral  hernia  takes  in  its  descent  is  at  first 
downwards,  then  forwards,  and  then  upwards;  and  in  endeavouring 
to  reduce  it,  the  application  of  the  taxis  must  have  reference  to  this 
course,  and  be  directed  in  precisely  the  reverse  order.  The  cover- 
ings of  femoral  hernia  are  the 

Integument, 
Superficial  fascia, 
Cribriform  fascia, 
Fascia  propria. 
Septum  crurale, 
Peritoneal  sac. 

The  fascia  of  the  leg  is  strong  in  the  anterior  tibial  region,  and 
gives  origin  by  its  inner  surface  to  the  upper  part  of  the  tibialis  anti- 
cus,  and  extensor  longus  digitorum  muscles. 

*  This  cellular  tissue  is  sometimes  very  considerably  thickened  by  a  deposit  of  fat 
within  its  cells,  and  forms  a  thick  stratum  over  the  hernial  sac. 


FASCIA  OF  THE  LEG.  259 

It  is  firmly  attached  to  the  tibia  and  fibula  at  each  side,  and  be- 
comes thickened  inferiorly  into  a  narrow  band,  the  anterior  annular 
ligament,  beneath  which  the  tendons  of  the  extensor  muscles  pass 
into  the  dorsum  of  the  foot  in  distinct  sheaths,  Uned  by  synovial 
bursse.  Upon  the  outer  side  it  forms  a  distinct  sheath  which  enve- 
lopes the  peronei  muscles,  and  ties  them  to  the  fibula.  The  anterior 
annular  ligament  is  attached  by  one  extremity  to  the  outer  side  of 
the  OS  calcis,  and  divides  in  front  of  the  joint  into  two  bands,;  one  of 
which  is  inserted  into  the  inner  malleolus,  while  the  other  spreads 
over  the  inner  side  of  the  foot,  and  becomes  continuous  with  the 
internal  portion  of  the  plantar  fascia. 

The  fascia  of  the  dorsum  of  the  foot  is  a  thin  layer  given  off  from 
the  lower  border  of  the  anterior  annular  ligament ;  it  is  continuous 
at  each  side  with  the  lateral  portions  of  the  plantar  fascia. 

The  fascia  of  the  posterior  part  of  the  leg  is  much  thinner  than  the 
anterior,  and  consists  of  two  layers,  superficial  and  deep.  The 
supeifcial  layer  is  continuous  with  the  posterior  fascia  of  the  thigh, 
and  is  increased  in  thickness  upon  the  outer  side  of  the  leg  by  an 
expansion  derived  from  the  tendon  of  the  biceps ;  it  terminates  infe- 
riorly in  the  external  and  internal  annular  ligaments.  The  deep 
layer  is  stretched  across  between  the  tibia  and  fibula,  and  forms  the 
intermuscular  fascia  between  the  superficial  and  deep  layer  of  mus- 
cles. It  covers  in  superiorly  the  popliteus  muscle,  receiving  a  tendi- 
nous expansion  from  the  semi-membranosus  muscle,  and  is  attached 
to  the  oblique  line  of  the  tibia. 

The  internal  annular  ligament  is  a  strong  fibrous  band  attached 
above  to  the  internal  malleolus,  and  below  to  the  side  of  the  inner 
tuberosity  of  the  os  calcis.  It  is  continuous  above  with  the  posterior 
fascia  of  the  leg,  and  below  with  the  plantar  fascia,  forming  sheaths 
for  the  passage  of  the  flexor  tendons  and  vessels,  into  the  sole  of  the 
foot. 

The  external  annular  ligament,  shorter  than  the  internal,  extends 
from  the  extremity  of  the  outer  malleolus  to  the  side  of  the  os  calcis, 
and  serves  to  bind  down  the  tendons  of  the  peronei  muscles  in  their 
passage  beneath  the  external  ankle. 

The  plantar  fascia  consists  of  three  portions,  a  middle  and  two 
lateral. 

The  middle  portion  is  thick  and  dense,  and  is  composed  of  strong 
tendinous  fibres,  closely  interwoven  with  each  other.  It  is  attached 
posteriorly  to  the  inner  tuberosity  of  the  os  calcis,  and  terminates 
under  the  heads  of  the  metatarsal  bones  in  five  fasciculi.  Each  of 
these  fasciculi  divides  into  two  slips,  which  are  inserted  into  each 
side  of  the  bases  of  the  first  phalanges  of  the  toes,  leaving  an  interval 
between  them  for  the  passage  of  the  flexor  tendons.  The  point  of 
division  of  this  fascia  into  fasciculi  and  slips,  is  strengthened  by 
transverse  bands,  which  preserve  the  solidity  of  the  fascia  at  its 
broadest  part.  The  intervals  between  the  toes  give  passage  to  the 
digital  arteries  and  nerves  and  the  lumbricales  muscles. 


260  PLANTAR  FASCIA. 

The  lateral  'portions  are  thin,  and  cover  the  sides  of  the  sole  of  the 
foot ;  they  are  continuous  behind  with  the  internal  and  external  an- 
nular ligaments ;  on  the  inner  side  with  the  middle  portion,  and  ex- 
ternally with  the  dorsal  fascia. 

Besides  constituting  a  strong  layer  of  investment  and  defence  to 
the  soft  parts  situated  in  the  sole  of  the  foot,  these  three  portions  of 
fascia  send  processes  inwards,  which  form  sheaths  for  the  different 
muscles.  A  strong  septum  is  given  off  from  each  side  of  the  middle 
portion  of  the  plantar  fascia,  which  is  attached  to  the  tarsal  bones, 
and  divides  the  muscles  into  three  groups,  a  middle  and  two  lateral; 
and  transverse  septa  are  stretched  between  these  to  separate  the 
layers.  The  superficial  layer  of  muscles  derive  a  part  of  their  ori- 
gin from  the  plantar  fascia. 


CHAPTER    V. 


ON  THE  ARTERIES. 


The  arteries  are  the  cylindrical  tubes  which  convey  the  blood 
from  the  ventricles  of  the  heart  to  every  part  of  the  body.  They 
are  dense  in  structure,  and  preserve  for  the  most  part  the  cyhndrical 
form  when  emptied  of  their  blood,  which  is  their  condition  after 
death :  hence  they  were  considered  by  the  ancients,  as  the  vessels 
for  the  transmission  of  the  vital  spirits,*  and  were  therefore  named 
arteries  (d^f  tyj^sTv,  to  contain  air). 

The  artery  proceeding  from  the  left  ventricle  of  the  heart  contains 
the  pure  or  arterial  blood,  which  is  distributed  throughout  the  entire 
system,  and  constitutes  with  its  returning  veins  the  greater  or  sys- 
temic circulation.  That  which  emanates  from  the  right  ventricle, 
conveys  the  impure  blood  to  the  lungs ;  and  with  its  corresponding 
veins  establishes  the  lesser  or  pulmonary  circulation. 

The  whole  of  the  arteries  of  the  systemic  circulation  proceed 
from  a  single  trunk,  named  the  aorta,  from  which  they  are  given  off 
as  branches,  and  divide  and  subdivide  to  their  ultimate  ramifications, 
constituting  the  great  arterial  tree  which  pervades  by  its  minute 
subdivisions  every  part  of  the  animal  frame.  The  mode  in  which 
the  division  into  branches  takes  place  is  deserving  of  remark.  From 
the  aorta  the  branches,  for  the  most  part,  pass  off  at  right  angles, 
as  if  for  the  purpose  of  checking  the  impetus  with  v^hich  the  blood 
would  otherwise  rush  along  their  cylinders  from  the  main  trunk ; 
but  in  the  limbs  a  very  different  arrangement  is  adopted ;  the  branches 
are  given  off"  from  the  principal  artery  at  an  acute  angle,  so  that  no 
impediment  may  be  offered  to  the  free  circulation  of  the  vital  fluid. 
The  division  of  arteries  is  usually  dichotomous,  as  of  the  aorta  into 
the  two  common  iliacs,  common  carotid  into  the  external  and  inter- 
nal, &c. ;  but  in  some  few  instances  a  short  trunk  divides  suddenly 
into  several  branches  which  proceed  in  different  directions ;  this 
mode  of  division  is  termed  an  axis,  as  the  thyroid  and  cceliac  axis. 

In  the  division  of  an  artery  into  two  branches,  it  is  observed  that 
the  combined  arose  of  the  two  branches  are  greater  than  that  of  the 
single  trunk ;  and  if  the  combined  areas  of  all  the  branches  at  the 
periphery  of  the  body  were  compared  with  that  of  the  aorta,  it 
would  be  seen  that  the  blood,  in  passing  from  the  aorta  into  the 
numerous  distributing  branches,  was  flowing  through  a  conical  tube 
of  which  the  apex  might  be  represented  by  the  aorta,  and  the  base 

*  To  Galen  is  due  the  honour  of  haviug  discovered  tliat  arteries  contained  blood,  and 
not  ail-. 


262  STRUCTURE  OP  ARTERIES. 

by  the  surface  of  the  entire  body.  The  advantage  of  this  important 
principle  in  faciUtating  the  circulation  is  sufficiently  obvious ;  for  the 
increased  channel  which  is  thus  provided  for  the  current  of  the  blood, 
serves  to  compensate  the  retarding  influence  of  friction,  resulting 
from  the  distance  of  the  heart  and  the  division  of  the  vessels. 

Communications  between  arteries  are  very  free  and  numerous, 
and  increase  in  frequency  with  the  diminution  in  the  size  of  the 
branches ;  so  that  through  the  medium  of  the  minute  ramifications, 
the  entire  body  may  be  considered  as  one  uninterrupted  circle  of 
inosculations,  or  anastomoses  (ava  between,  tfTo/j-a  mouth).  This  in- 
crease in  the  frequency  of  anastomosis  in  the  smaller  branches  is  a 
provision  for  counteracting  the  greater  liability  to  impediment  exist- 
ing in  them  than  in  the  larger  branches.  Where  freedom  of  circu- 
lation is  of  vital  importance,  this  communication  of  the  arteries  is 
very  remarkable,  as  in  the  circle  of  Willis  in  the  cranium,  or  in  the 
distribution  of  the  arteries  of  the  heart.  It  is  also  strikingly  seen  in 
situations  where  obstruction  is  most  likely  to  occur,  as  in  the  dis- 
tribution to  the  alimentary  canal,  around  joints,  or  in  the  hand  and 
foot.  Upon  this  free  communication  existing  every  where  between 
arterial  branches  is  founded  the  principle  of  cure  in  the  ligature  of 
large  arteries ;  the  ramifications  of  the  branches  given  oflf  from  the 
artery  above  the  ligature  inosculate  with  those  which  proceed  from 
the  trunk  of  the  vessel  below  the  ligature:  these  anastomosing 
branches  enlarge  and  constitute  a  collateral  circulation,  in  which,  as 
is  shown  in  the  beautiful  preparations  made  by  Sir  Astley  Cooper, 
several  large  branches  perform  the  office  of  the  single  obliterated 
trunk.* 

The  arteries  do  not  terminate  directly  in  veins ;  but  in  an  inter- 
mediate system  of  vessels,  which,  from  their  minute  size,  are  termed 
capillaries  (capillus,  a  hair).  The  capillaries  constitute  a  micro- 
scopic network,  which  is  distributed  through  every  part  of  the  body, 
so  as  to  render  it  impossible  to  introduce  the  smallest  needle-point 
beneath  the  skin  without  wounding  several  of  these  fine  vessels.  It 
is  through  the  medium  of  the  capillaries  that  all  the  phenomena  of 
nutrition  and  secretion  are  performed.  They  are  remarkable  for 
their  uniformity  of  diameter,  and  for  the  constant  divisions  and 
communications  which  take  place  between  them  without  any  altera- 
tion of  size.  They  inosculate  on  one  hand  with  the  terminal  ram- 
usculi  of  the  arteries ;  and  on  the  other  with  the  minute  radicles  of 
the  veins. 

Arteries  are  composed  of  three  coats,  external,  middle,  and  in- 
ternal The  external  or  cellular  coat  is  firm  and  strong,  and  serves 
at  the  same  time  as  the  chief  means  of  resistance  of  the  vessel,  and 
of  connexion  to  surrounding  parts.  It  consists  of  condensed  cellular 
tissue,  strengthened  by  an  interlacement  of  ghstening  fibres  which 


*  I  have  a  preparation,  showing  the  collaternl  circulation  in  a  dog,  in  whom  T  tied 
the  abdorainul  aorta  ;  the  animai  died  from  over-ffcding-  nearly  two  years  after  the 
operation. 


AORTA.  263 

partially  encircle  the  cylinder  of  the  tube  in  an  oblique  direction. 
Upon  the  surface  the  cellular  tissue  is  loose,  to  permit  of  the  move- 
ments of  the  artery  in  distension  and  contraction. 

The  middle  or  fibrous  coat  is  composed  of  yellowish  fibres  of 
elastic  tissue,  which  are  disposed  in  an  oblique  direction  around  the 
cylinder  of  the  vessel,  and  cross  each  other  in  their  course.  This 
coat  is  elastic  and  fragile,  and  thicker  than  the  external  coat.  Its 
elasticity  enables  the  vessel  to  accommodate  itself  to  the  quantity  of 
blood  which  it  may  contain ;  its  fragility  is  exhibited  in  some  cases 
of  aneurism,  and  in  the  division  of  the  two  internal  coats  of  an  artery 
by  a  ligature. 

The  internal  coat  is  a  thin  serous  membrane  which  lines  the  in- 
terior of  the  artery,  and  gives  it  the  smooth  polish  which  that  sur- 
face presents.  It  is  continuous  with  the  lining  membrane  of  the 
heart,  and  through  the  medium  of  the  capillaries  with  the  venous 
system.  The  internal  is  connected  to  the  fibrous  coat  by  a  close 
cellular  tissue  which  is  very  liable  to  disease  and  depositions  of 
various  kinds ;  and  is  the  seat  of  the  first  changes  which  precede 
aneurism.  The  researches  of  Henle  have  demonstrated  an  epithe- 
lium, composed  of  vesicles  and  scales,  with  central  nuclei,  upon  the 
surface  of  this  internal  coat,  analogous  to  the  epithelium  of  serous 
and  mucous  membranes. 

The  arteries  in  their  distribution  through  the  body  are  included 
in  a  loose  cellular  investment  which  separates  them  from  the  sur- 
rounding tissues,  and  is  called  a  sheath.  Around  the  principal  ves- 
sels the  sheath  is  an  important  structure  ;  it  is  composed  of  cellulo- 
fibrous  tissue,  intermingled  with  tendinous  fibres,  and  is  continuous 
with  the  fascia  of  the  region  in  which  the  arteries  are  situated,  as 
with  the  thoracic  and  cervical  fascia  in  the  neck,  transversalis  and 
iliac  fasciae,  and  fascia  lata  in  the  thigh,  &c.  The  sheath  of  the 
arteries  contains  also  their  accompanying  veins,  and  sometimes  a 
nerve. 

The  coats  of  arteries  are  supplied  with  blood  like  other  organs  of 
the  body,  and  the  vessels  which  are  distributed  to  them  are  named 
Vasa  vasorum.  They  are  also  provided  with  nerves ;  but  the  mode 
of  distribution  of  the  nerves  is  at  present  undiscovered. 

In  the  consideration  of  the  arteries,  we  shall  first  describe  the 
aorta,  and  the  branches  of  that  trunk,  with  their  subdivisions,  which 
together  constitute  the  efferent  portion  of  the  systemic  circulation  : 
and  then  the  pulmonary  artery  as  the  efferent  trunk  of  the  pulmo- 
nary circulation. 

AORTA. 

The  Aorta  arises  from  the  left  ventricle,  at  the  middle  of  the  root 
of  the  heart,  opposite  the  articulation  of  the  fourth  costal  cartilage 
with  the  sternum.  At  its  commencement  it  presents  three  dilata- 
tions, called  the  sinus  aortici,  which  correspond  with  the  semilunar 
valves.     It  ascends  at  first  to  the  right,  then  curves  backwards  and 


264 


AORTA. 


to  the  left,  and  descends  on  the  left  side  of  the  vertebral  column  to 
the  fourth  lumbar  vertebra.  Hence  it  is  divided  into — ascending — 
arch — and  descending  aorta. 

Relations. — The  ascendivg  aorta  has  in  relation  with  it,  in  front, 
the  trunk  of  the  pulmonary  artery,  thoracic  fascia,  and  pericardium ; 
behind,  the  right  pulmonary  veins  and  artery;  to  the  right  side,  the 
right  auricle  and  superior  cava ;  and  to  the  left,  the  left  auricle  and 
the  trunk  of  the  pulmonary  artery. 

Fig.  102.* 


*  The  large  vessels  which  proceed  from  the  root  of  the  heart,  with  their  relations ; 
the  heart  has  been  removed.  1.  The  ascending  aorta.  2.  The  arch.  3.  The  thoracic 
portion  of  the  descending  aorta.  4.  The  arteria  innominata  dividing  into,  5,  the  right 
carotid,  which  again  divides  at  6,  into  the  external  and  internal  carotid;  and  7,  the 
right  subclavian  artery.  8.  The  axillary  artery  :  its  extent  is  designated  by  a  dotted 
line.  9.  The  brachial  artery.  10.  The  right  pneumogasiric  nerve  running  by  the  side 
of  the  common  carotid,  in  front  of  the  right  subclavian  artery,  and  behind  the  root  of 
tlie  right  lunp-.  11.  The  left  common  carotid,  having  to  its  outer  side  the  left  pneumo- 
gastric  nerve,  which  crosses  the  arch  of  the  aorta,  and  as  it  reaches  its  lower  border  is 
seen  to  give  off  the  left  recurrent  nerve.  12.  The  left  subclavian  artery  becoming 
axillary,  and  brachial  in  its  course,  like  the  artery  of  the  opposite  side.  13.  The  trunk 
of  the  pulmonary  artery  connected  to  the  concavity  of  the  arch  of  the  aorta  by  a  fibrous 
cord,  the  remains  of  the  ductus  arteriosus.  14.  Tiie  left  pulmonary  artery.  1.5.  The 
right  pulmonary  artery.  IG.  The  traciiea.  17.  The  right  bronchus.  18.  The  left 
bronchus.  19,  19.  The  pulmonary  veins.  17,  l.*),  and  19,  on  the  right  side,  and  14, 
18,  and  19,  on  the  left,  constitute  the  roots  of  the  corresponding  lungs,  and  the  relative 
position  of  these  vessels  is  carefully  preserved.  20.  Bronchial  arteries.  21,21.  Inter- 
costal arteries;  the  branches  from  the  front  of  the  aorta  above  and  below  the  number  3 
are  pericardiac  and  oesophageal  branches. 


ASCENDING  AORTA — ARCH. 


265 


Plan  of  the  relations  of  the  ascending  Aorta. 

In  Front. 
Pericardium, 
Thoracic  fascia, 
Pulmonary  artery. 


Right  Side, 
Superior  cava. 
Right  auricle. 


Ascending  Aorta. 


Left  Side. 
Pulmonary  artery, 
Left  auricle. 


Behind. 
Right  pulmonary  artery, 
Right  pulmonary  veins. 

Arch. — The  upper  border  of  the  arch  is  parallel  with  the  upper 
border  of  the  second  sterno-costal  articulation  of  the  right  side  in 
front,  and  the  second  dorsal  vertebra  behind,  and  terminates  opposite 
the  lower  border  of  the  third. 

The  anterior  surface  of  the  arch  is  crossed  by  the  left  pneumo- 
gastric  nerve,  and  by  the  cardiac  branches  of  that  nerve,  and  of  the 
sympathetic. 

The  posterior  surface  of  the  arch  is  in  relation  with  the  bifurca- 
tion of  the  trachea  and  great  cardiac  plexus,  the  cardiac  nerves,  left 
recurrent  nerve,  and  the  thoracic  duct. 

The  superior  border  gives  off  the  three  great  arteries,  viz.  the  in- 
nominata,  left  carotid,  and  left  subclavian. 

The  inferior  border,  or  concavity  of  the  arch,  is  in  relation  with 
the  remains  of  the  ductus  arteriosus,  the  cardiac  ganglion  and  left 
recurrent  nerve,  and  has  passing  beneath  it  the  right  pulmonary 
artery  and  left  bronchus. 

Plan  of  the  relations  of  the  arch  of  the  Aorta. 

Above. 
Arteria  innorainata. 


Left  carotid, 
Left  subclavian. 


In  Front. 


Left  pneumogastric  nerve. 
Cardiac  nerves. 


Arch 
of  the  Aorta. 


Behind, 
Bifurcation  of  the  trachea, 
Great  cardiac  plexus. 
Cardiac  nerves. 
Left  recurrent  nerve, 
Thoracic  duct. 


Below. 
Cardiac  ganglion. 
Remains  of  ductus  arteriosus, 
Left  recurrent  nerve, 
Right  pulmonary  artery. 
Left  bronchus. 

The  descending  aorta  is  subdivided,  in  correspondence  with  the 
two  great  cavities  of  the  trunk,  into  the  thoracic  and  abdominal 
aorta. 

The  thoracic  aorta  is  situated  to  the  left  side  of  the  vertebral 

34 


266 


THORACIC  AORTA ABDOMINAL  AORTA. 


column,  but  approaches  the  middle  line  as  it  descends,  and  at  the 
aortic  opening  of  the  diaphragm  is  altogether  in  front  of  the  column. 
After  entering  the  abdomen  it  again  falls  back  to  the  left  side. 

Relations. — It  is  in  relation,  behind  with  the  vertebral  column 
and  lesser  vena  azygos ;  in  front  with  the  oesophagus  and  right 
pneumogastric  nerve  ;  to  the  left  side  with  the  pleura  ;  and  to  the 
right  with  the  thoracic  duct. 

Plan  of  the  relations  of  the  thoracic  Aorta. 

In  Front. 
CEsophagus, 
Right  pneumogastric  nerve. 


Right  Side. 
Thoracic  duct. 


Thoracic  Aorta. 


Left  Side. 
Pleura. 


Behind. 
Lesser  vena  azygos, 
Vertebral  column. 


The  abdominal  aorta  enters  the  abdomen  through  the  aortic  open- 
ing of  the  diaphragm,  and  descends,  lying  rather  to  the  left  side  of 
the  vertebral  column,  to  the  fourth  lumbar  vertebra,  where  it  divides 
into  the  two  common  iliac  arteries. 

Relations. — It  is  crossed,  in  front  by  the  left  renal  vein,  pancreas, 
transverse  duodenum,  and  mesentery,  and  is  embraced  by  the  aortic 
plexus ;  behind  it  is  in  relation  with  the  thoracic  duct,  receptaculum 
chyli,  and  left  lumbar  veins.  ' 

On  its  left  side  is  the  left  semilunar  ganglion  and  sympathetic 
nerve ;  and  on  the  right  the  vena  cava,  right  semilunar  ganglion, 
and  the  commencement  of  the  vena  azygos. 


Plan  of  the  relations  of  the  abdominal  Aorta. 

In  Front. 
Left  renal  vein. 
Pancreas, 

Transverse  duodenum, 
Mesentery, 
Aortic  plexus. 


Right  Side. 
Vena  cava, 

Right  semilunar  ganglion. 
Vena  azygos. 


Behind. 
Thoracic  duct, 
Receptaculum  chyli. 
Left  lumbar  veins. 


Left  Side. 

Left  semilunar  gan- 
glion. 
Sympathetic  nerve. 


ARTERIA.  INNOMINATA. 


267 


Branches.- 
are — 


-The  branches  of  the  aorta,  arranged  in  a  tabular  form, 


Ascending  aorta 
Arch  of  the  aorta 

Thoracic  aorta 


Right  carotid, 
Right  subclavian. 


Abdominal  aoj^ta 


Coronary. 

Arteria  innominata, 
Left  carotid, 
Left  subclavian. 

Pericardiac, 
Bronchial, 
1  (Esophageal, 
Intercostal. 

Phrenic, 

C  Gastric, 
Coeliac  axis,  <  Hepatic, 

(  Splenic. 
Supra-renal,  or  capsular, 
Renal,  or  emulgent, 
Superior  mesenteric, 
Spermatic, 
Inferior  mesenteric, 
Lumbar, 
Sacra  media, 
Common  iliacs. 


The  coronary  arteries  arise  from  the  aortic  sinuses  at  the  com- 
mencement of  the  ascending  aorta,  immediately  above  the  free 
margin  of  the  semilunar  valves.  The  left,  or  anterior  coronary  passes 
forwards,  between  the  pulmonary  artery  and  left  appendix  auriculae, 
and  divides  into  two  branches  ;  one  of  which  winds  around  the 
base  of  the  left  ventricle,  in  the  auriculo-ventricular  groove,  and 
inosculates  with  the  right  coronary,  forming  an  arterial  circle  around 
the  base  of  the  heart,  while  the  other  passes  along  the  line  of  union 
of  the  two  ventricles,  upon  the  anterior  aspect  of  the  heart,  to  its 
apex,  where  it  anastomoses  with  the  descending  branch  of  the  right 
coronary.  It  supplies  the  left  auricle  and  the  adjoining  sides  of 
both  ventricles. 

The  right,  or  posterior  coronary  passes  forwards,  between  the  root 
of  the  pulmonary  artery  and  the  right  auricle,  and  winds  along  the 
auriculo-ventricular  groove,  to  the  posterior  median  furrow,  where 
it  descends  upon  the  posterior  aspect  of  the  heart  to  its  apex,  and 
inosculates  with  the  left  coronary.  It  is  distributed  to  the  right 
auricle  and  to  the  posterior  surface  of  both  ventricles,  and  sends  a 
large  branch  along  the  sharp  margin  of  the  right  ventricle  to  the 
apex  of  the  heart. 

ARTERIA  INNOMINATA. 

The  Arteria  innominata  (fig.  102,  No.  4,)  is  the  first  artery  given 
off  by  the  arch  of  the  aorta.     It  is  an  inch  and  a  half  in  length, 


268  COMMON  CAROTID  ARTERIES. 

and  ascends  obliquely  to  the  right  sterno-clavicular  articulation, 
where  it  divides  into  the  right  carotid  and  right  subclavian  artery. 

Relations. — It  is  in  relation,  in  front  with  the  left  vena  innomi- 
nata,  the  thymus  gland,  and  the  origins  of  the  sterno-thyroid  and 
sterno-hyoid  muscles,  which  separates  it  from  the  sternum.  Behind 
with  the  trachea,  pneumogastric  nerve  and  cardiac  nerves ;  exter- 
nally with  the  right  vena  innominata  and  pleura;  and  internally  with 
the  origin  of  the  left  carotid. 

Plan  of  the  relations  of  the  Arteria  Innominata. 

In  Front, 
Left  vena  innominata, 
Thymus  gland, 
Sterno-thyroid, 
Sterno-hyoid. 


Right  Side. 
Right  vena  innominata, 
Pleura. 


Arteria  innominata. 


Left  Side. 
Left  carotid. 


Behind. 
Trachea, 

Pneumogastric  nerve. 
Cardiac  nerves. 

The  arteria  innominata  occasionally  gives  off  a  small  branch 
which  ascends  along  the  middle  of  the  trachea  to  the  thyroid  gland. 
This  branch  was  described  by  Neubauer,  and  Dr.  Harrison  names 
it  the  middle  thyroid  artery.  A  knowledge  of  its  existence  is  ex- 
tremely important  in  performing  the  operation  of  tracheotomy. 

COMMOKr  CAROTID  ARTERIES. 

The  common  carotid  arteries  (xapa,  the  head)  arise,  the  right  from 
the  bifurcation  of  the  arteria  innominata  opposite  the  right  sterno- 
clavicular articulation,  the  left  from  the  arch  of  the  aorta.  It  fol- 
lows, therefore,  that  the  right  carotid  is  shorter  than  the  left;  it  is 
also  more  anterior;  and, in  consequence  of  proceeding  from  a  branch 
instead  of  from  the  main  trunk,  it  is  larger  than  its  fellow. 

The  Right  common  carotid  artery  (fig.  102,  No.  5)  ascends  the 
neck  perpendicularly,  from  the  right  sterno-clavicular  articulation 
to  a  level  with  the  upper  border  of  the  thyroid  cartilage,  where  it 
divides  into  the  external  and  internal  carotid. 

The  Left  common  carotid  (fig.  102,  No.  11)  passes  somewhat  ob- 
liquely outwards  from  the  arch  of  the  aorta  to  the  side  of  the  neck, 
and  thence  upwards  to  a  level  with  the  upper  border  of  the  thyroid 
cartilage,  where  it  divides  like  the  right  common  carotid  into  the 
external  and  internal  carotid. 

Relations. — The  right  common  carotid  rests,  first,  upon  the  longus 
colli  muscle,  then  upon  the  rectus  anticus  major,  the  sympathetic 
nerve  being  interposed.  The  inferior  thyroid  artery  and  recurrent 
laryngeal  nerve  pass  behind  it  at  its  lower  part.  To  its  inner  side 
is  the  trachea,  recurrent  laryngeal  nerve,  and  larynx;  to  its  outer 
side,  and  enclosed  in  the  same  sheath,  the  jugular  vein  and  pneumo- 


EXTERNAL  CAROTID  ARTERY. 


269 


gastric  nerve;  and  in  front  the  sterno-thyroid,  sterno-hyoid,  sterno- 

mastoid,  omo-hyoid,  and  platysma  muscles,  and  the  descendens  noni 
nerve.  The  left  common  carotid,  in  addition  to  the  relations  just 
enumerated,  which  are  common  to  both,  is  crossed  near  its  com- 
mencement by  the  left  vena  innominata;  it  lies  upon  the  trachea; 
then  gets  to  its  side,  and  is  in  relation  with  the  oesophagus  and  tho- 
racic duct :  to  facilitate  the  study  of  these  relations,  I  have  arranged 
them  in  a  tabular  form. 

Plan  of  relations  of  the  Common  Carotid  Artery. 

In  Front. 

Platysma, 

Descendens  noni  nerve, 

Omo-hyoid, 

Sterno-mastoid, 

Sterno-hyoid, 

Sterno-thyroid. 


Externally. 
Internal  jugular  vein, 
Pneumogastric  nerve. 


Common 
Carotid  Artery. 


Internally. 
Trachea, 
Larynx, 
Recurrent  laryngeal 


Behind. 

Longus  colli. 

Rectus  anticus  major. 

Sympathetic, 

Inferior  thyroid  artery. 

Recurrent  laryngeal  nerve. 

Additional  relations  of  the  Left  Common  Carotid. 


In  Front. 

Left  vena  innominata. 


Behind. 
Trachea, 
Thoracic  duct. 


Internally. 
Arteria  innominata, 
(Esophagus. 


Externally. 
Pleura. 


EXTERN.'IL  CAROTID  ARTERY. 


The  External  carotid  artery  ascends  nearly  perpendicularly  from 
opposite  the  upper  Itorder  of  the  thyroid  cartilage,  to  the  space  be- 
tween the  neck  of  the  lower  jaw  and  the  meatus  auditorius,  where 
it  divides  into  the  temporal  and  internal  maxillary  artery. 

Relations. — In  front  it  is  crossed  by  the  posterior  belly  of  the 
digastricus,  stylo-hyoideus,  and  platysma  myoides  muscles;  by  the 
lingual  nerve  near  its  origin;  higher  up  it  is  situated  in  the  sub- 
stance of  the  parotid  gland,  and  is  crossed  by  the  facial  nerve.  Be- 
hind it  is  separated  from  the  internal  carotid  by  the  stylo-pharyngeus 
and  stylo-glossus  muscles,  glosso-pharyngeal  nerve,  and  part  of  the 
parotid  gland. 


270  SUrEKIOR  THYROID  ARTERY. 

Plan  of  the  relations  of  the  External  Carotid  Artery. 

In  Front.   ' 
Platysma, 
Digastricus, 
Stylo-h)'oid, 
Lingual  nerve, 
Facial  nerve, 
Parotid  gland. 


Behind. 
Stylo-pharyngeus, 
Stylo-glossus, 
Glosso-pharyngeal  nerve, 
Parotid  gland. 

Branches. — The  branches  of  the  external  carotid  are  eleven  in 
number,  and  may  be  arranged  into  four  groups,  viz. 

Anterior.  Posterior. 

1.  Superior  thyroid,  4.  Mastoid, 

2.  Lingual,  5.  Occipital, 

3.  Facial.  6.  Posterior  auricular. 

Superior.  Terminal. 

7.  Parotidean,  10.  Temporal. 

8.  Ascending  pharyngeal,  1 1 .  Internal  maxillary. 

9.  Transverse  facial. 

The  anterior  branches  arise  from  the  commencement  of  the  exter- 
nal carotid,  within  a  short  distance  of  each  other.  The  lingual  and 
facial  bifurcate,  not  unfrequently,  from  a  common  trunk. 

1.  The  Superior  Thyroid  Artery  (the  first  of  the  branches  of 
the  external  carotid)  curves  downwards  to  the  thyroid  gland  to  which 
it  is  distributed,  anastomosing  with  its  fellow  of  the  opposite  side, 
and  with  the  inferior  thyroid  arteries.  In  its  course  it  passes  be- 
neath the  omo-hyoid,  sterno-thyroid,  and  sterno-hyoid  muscle. 

Branches. 

Hyoid, 

Superior  laryngeal, 
Inferior  laryngeal. 
Muscular. 

The  Hyoid  branch  passes  forwards  beneath  the  thyro-hyoideus, 
and  is  distributed  to  the  insertion  of  the  depressor  muscles^  into  the 
OS  hyoidcs. 

The  Superior  laryngeal  pierces  the  thyro-hyoidcan  membrane,  in 
company  with  the  superior  laryngeal  nerve,  and  supplies  the  mucous 
membrane  and  muscles  of  the  larynx,  sending  a  branch  upwards  to 
the  epiglottis. 


LINGUAL  ARTEEY. 


271 


The  Inferior  laryngeal  is  a  small  branch  which  crosses  the  crico- 
thyroidean  membrane  along  the  lower  border  of  the  thyroid  cartilage. 
It  sends  branches  through  the  membrane  to  supply  the  mucous  lining 
of  the  larynx,  and  inosculates  with  its  fellow  of  the  opposite  side. 

Fig.  103.* 


The  muscular  branches  are  distributed  to  the  depressor  muscles  of 
the  OS  hyoides  and  larynx.  One  of  these  branches  crosses  the  sheath 
of  the  common  carotid  to  the  under  surface  of  the  sterno-mastoid 
muscle. 

2.  The  Lingual  Artery  ascends  obliquely  from  its  origin,  it  then 
passes  forwards  parallel  with  the  os  hyoides ;  thirdly,  it  ascends  to 
the  under  surface  of  the  tongue ;  and  fourthly,  runs  forward  in  a 
serpentine  direction  to  its  tip,  under  the  name  of  ranine  artery, 
where  it  terminates  by  inosculating  with  its  fellow  of  the  opposite 
side. 

Relations. — The ^rs^  part  of  its  course  rests  upon  the  middle  con- 
strictor muscle  of  the  pharynx,  being  covered  in  by  the  tendon  of 
the  digastricus  and  the  stylo-hyoid  muscle ;  the  second  is  situated 
between  the  middle  constrictor  and  hyo-glossus  muscle,  the  latter 
separating  it  from  the  lingual  nerve ;  in  the  third  part  of  its  course 

*  The  carotid  arteries  with  the  branches  of  the  external  carotid.  1.  The  common 
carotid.  2.  The  external  carotid.  3.  The  internal  carotid.  4.  The  carotid  foramen 
in  the  petrous  portion  of  the  temporal  bone.  5.  The  superior  tliyroid  artery.  6.  The 
lingual  artery.  7.  The  facial  artery.  8.  The  mastoid  artery.  9.  The  occipital.  10. 
The  posterior  auricular.  11.  The  transverse  facial  artery.  12.  The  internal  ma.xil- 
lary.     13.  The  temporal.     14.  The  ascending  pharyngeal  artery. 


272  FACIAL  ARTERY. 

it  lies  between  the  hyo-glossus  and  genio-hyo-glossus ;  and  in  the 
fourth  (ranine)  rests  upon  the  HnguaUs  to  the  tip  of  the  tongue. 

Branches. 

Hyoid, 

Dorsalis  hngua3, 
Sublingual. 

The  Hyoid  branch  runs  along  the  upper  border  of  the  os  hyoides, 
and  is  distributed  to  the  origins  of  the  elevator  muscles  of  the  os 
hyoides,  inosculating  with  its  fellow  of  the  opposite  side. 

The  Do7'saIis  linguce  ascends  along  the  posterior  border  of  the 
hyo-glossus  muscle  to  the  dorsum  of  the  tongue,  and  is  distributed 
to  the  tongue,  the  fauces  and  epiglottis,  anastomosing  with  its  fellow 
of  the  opposite  side. 

The  Sublingual  branch,  frequently  considered  as  a  branch  of 
bifurcation  of  the  lingual,  runs  along  the  anterior  border  of  the  hyo- 
glossus,  and  is  distributed  to  the  sublingual  gland  and  to  the  muscles 
of  the  tongue.  It  is  situated  between  the  mylo-hyoideus  and  genio- 
hyo-glossus,  generally  accompanies  Wharton's  duct  for  a  part  of  its 
course,  and  sends  a  branch  to  the  fraenum  Hnguse.  It  is  the  latter 
branch  which  affords  the  considerable  haemorrhage  which  some- 
times accompanies  the  operation  of  snipping  the  froenum  in  children. 

3.  Facial  Artery. — The  Facial  artery  arises  a  little  above  the 
great  cornu  of  the  os  hyoides  and  ascends  obliquely  to  the  submax- 
illary gland,  in  which  it  lies  embedded.  It  then  curves  around  the 
body  of  the  lower  jaw,  close  to  the  anterior  inferior  angle  of  the 
massetcr  muscle,  ascends  to  the  angle  of  the  mouth,  and  thence  to 
the  angle  of  the  eye,  where  it  is  named  the  angular  artery.  The 
facial  artery  is  very  tortuous  in  its  course  over  the  buccinator  mus- 
cle, to  accommodate  itself  to  the  movement  of  the  jaws. 

Relations. — Below  the  jaw  it  passes  beneath  the  digastricus  and 
stylo-hyoid  muscles  ;  on  the  body  of  the  lower  jaw  it  is  covered  by 
the  platysma  myoides,  and  at  the  angle  of  the  mouth  by  the  depressor 
anguli  oris  and  zygomatic  muscles.  It  rests  upon  the  submaxillary 
gland,  the  lower  jaw,  buccinator,  orbicularis  oris,  levator  anguli  oris, 
levator  labii  superioris  proprius,.and  levator  labii  supcrioris  alseque 
nasi. 

Its  branches  are  divided  into  those  which  are  given  off  below  the 
jaw  and  those  on  the  face :  they  may  be  thus  arranged  : — 


Below  the  Jaw. 

Inferior  palatine, 
Submaxillary, 
Submental, 
Pterygoid. 


FACIAL OCCIPITAL.  273 

On  the  Face. 

Masseteric, 
Inferior  labial, 
Inferior  coronary, 
Superior  coronary, 
Lateralis  nasi. 

The  Inferior-  palatine  branch  ascends  between  the  stylo-glossus 
and  stylo-pharyngeus  muscles,  to  be  distributed  to  the  tonsil  and  soft 
palate,  and  anastomoses  with  the  posterior  palatine  branch  of  the 
internal  maxillary  artery. 

The  Submaxillary  are  four  or  five  branches  which  supply  the  sub- 
maxillary gland. 

The  Submental  branch  runs  forwards  upon  the  mylo-hyoid  muscle, 
under  cover  of  the  body  of  the  lower  jaw,  and  anastomoses  with 
branches  of  the  sublingual  and  inferior  dental  artery. 

The  Pterygoid  branch  is  distributed  to  the  internal  pterygoid 
muscle. 

The  Masseteric  branches  are  distributed  to  the  masseter  and  buc- 
cinator muscles. 

The  Inferior  labial  branch  is  distributed  to  the  muscles  and  integu- 
ment of  the  lower  lip. 

The  Inferior  coronary  runs  along  the  edge  of  the  lower  lip, 
between  the  mucous  membrane  and  labial  glands,  and  the  orbicu- 
laris oris  ;  it  inosculates  with  the  corresponding  artery  of  the  oppo- 
site side. 

The  Superior  coronary  follows  the  same  course  along  the  upper 
lip,  inosculating  with  the  opposite  superior  coronary  artery,  and  at 
the  middle  of  the  Up  it  sends  a  branch  upwards  to  supply  the  septum 
of  the  nose  and  the  mucous  membrane. 

The  Lateralis  nasi  is  distributed  to  the  ala  and  septum  of  the 
nose. 

The  Inosculations  of  the  facial  artery  are  very  numerous :  thus 
it  anastomoses  with  the  sublingual  branch  of  the  lingual,  with  the 
ascending  pharyngeal  and  posterior  palatine  arteries,  with  the  inferior 
dental  as  it  escapes  from  the  mental  foramen,  infra-orbital  at  the 
infra-orbital  foramen,  transverse  facial  on  the  side  of  the  face,  and 
at  the  angle  of  the  eye  with  the  nasal  and  frontal  branches  of  the 
ophthalmic  artery. 

The  facial  artery  is  subject  to  considerable  varieties  in  its  extent ; 
it  not  unfrequently  terminates  at  the  angle  of  the  nose  or  mouth,  and 
is  rarely  symmetrical  on  both  sides  of  the  face. 

4.  The  Mastoid  Artery  turns  downwards,  to  be  distributed  to 
the  sterno-mastoid  muscle,  and  to  the  lymphatic  glands  of  the  neck  ; 
sometimes  it  is  replaced  by  two  small  branches. 

5.  The  Occipital  Artery,  smaller  than  the  preceding  branches, 
passes  backwards  beneath  the  posterior  belly  of  the  digastricus,  the 
trachelo-mastoid  and  sterno-mastoid  muscles,  to  the  occipital  groove 

35 


274  POSTERIOR   AURICULAR TEMPORAL. 

in  the  mastoid  portion  of  the  temporal  bone.  It  then  ascends 
between  the  splenius  and  complexus  muscles,  and  divides  into  two 
branches  which  are  distributed  upon  the  occiput,  anastomosing  with 
the  opposite  occipital,  the  posterior  auricular,  and  temporal  artery. 
The  lingual  nerve  curves  around  this  artery  near  to  its  origin  from 
the  external  carotid. 

Branches. — It  gives  off  only  two  branches  deserving  of  name, 
the  inferior  meningeal  and  princeps  cervicis. 

The  Inferior  meningeal  ascends  by  the  side  of  the  internal  jugular 
vein,  and  passes  through  the  foramen  lacerum  posterius,  to  be  dis- 
tributed to  the  dura  mater. 

The  Arteria  prince'ps  cervicis  is  a  large  and  irregular  branch.  It 
descends  the  neck  between  the  complexus  and  semi-spinahs  coUi, 
and  inosculates  with  the  profunda  cervicis  of  the  subclavian.  This 
branch  is  the  means  of  estabhshing  a  very  important  collateral  cir- 
culation between  the  branches  of  the  carotid  and  subclavian,  in  liga- 
ture of  the  common  carotid  artery. 

6.  The  Posterior  Auricular  Artery  arises  from  the  external 
carotid,  above  the  digastric  and  stylo-hyoid  muscles,  and  ascends 
beneath  the  lower  border  of  the  parotid  gland,  and  behind  the  concha, 
to  be  distributed  by  two  branches  to  the  external  ear  and  side  of  the 
head,  anastomosing  with  the  occipital  and  temporal  arteries  ;  some 
of  its  branches  pass  through  fissures  in  the  fibro-cartilage,  to  be  dis- 
tributed to  the  anterior  surface  of  the  pinna.  The  anterior  auricular 
arteries  are  branches  of  the  temporal. 

Branches. — The  posterior  auricular  gives  off  but  one  named 
branch,  the  styh-mastoid,  which  enters  the  stylo-mastoid  foramen  to 
be  distributed  to  the  aquseductus  Fallopii  and  tympanum. 

7.  The  Parotidean  Arteries  are  four  or  five  large  branches 
which  are  given  off"  from  the  external  carotid  whilst  that  vessel  is 
situated  in  the  parotid  gland.  They  are  distributed  to  the  structure 
of  the  gland,  their  terminal  branches  reaching  the  integument  and 
the  side  of  the  face. 

8.  The  Ascending  Pharyngeal  Artery,  the  smallest  of  the 
branches  of  the  external  carotid,  arises  from  that  trunk  near  to  its 
bifurcation,  and  ascends  between  the  internal  carotid  and  the  side  of 
the  pharynx  to  the  base  of  the  skull,  where  it  divides  into  two 
branches  ;  meningeal,  which  enters  the  foramen  lacerum  posterius, 
to  be  distributed  to  the  dura  mater ;  and  pharyngeal.  It  supplies 
the  pharynx,  tonsils,  and  Eustachian  tube. 

9.  The  Transversalis  Faciei  arises  from  the  external  carotid 
whilst  that  trunk  is  lodged  within  the  parotid  gland  ;  it  crosses  the 
masseter  muscle,  lying  parallel  with  and  a  little  above  Stenon's  duct ; 
and  is  distributed  to  the  temporo-maxillary  articulation,  and  to  the 
muscles  and  integument  on  the  side  of  the  face,  inosculating  with 
the  infra-orbital  and  facial  artery.  This  artery  is  not  unfrequently 
a  branch  of  the  temporal. 

10.  The  Temporal  Artery  is  one  of  the  two  terminal  branches 
of  the  external  carotid.     It  ascends  over  the  root  of  the  zygoma ; 


INTERNAL  MAXILLARY  ARTERY.  275 

and  at  about  an  inch  and  a  half  above  the  zygomatic  arch,  divides 
into  an  anterior  and  a  posterior  temporal  branch.  The  anterior 
temporal  is  distributed  over  the  front  of  the  temple  and  arch  of  the 
skull,  and  anastomoses  with  the  opposite  anterior  temporal,  and  with 
the  supra-orbital  and  frontal  artery.  The  posterior  temporal  curves 
upwards  and  backwards,  and  inosculates  with  its  fellow  of  the  oppo- 
site side,  with  the  posterior  auricular  and  occipital  artery. 

The  trunk  of  the  temporal  artery  is  covered  in  by  the  parotid 
gland  and  by  the  attrahens  aurem  muscle,  and  rests  upon  the  tem- 
poral fascia. 

Branches. 

Orbitar, 

Anterior  auricular. 

Middle  temporal. 

The  Orbitar  artery  is  a  small  branch,  not  always  present,  which 
passes  forwards  immediately  above  the  zygoma,  between  the  two 
layers  of  the  temporal  fascia,  and  inosculates  beneath  the  orbicularis 
palpebrarum  with  the  palpebral  arteries. 

The  Anterior  auricular  arteries  are  distributed  to  the  anterior  por- 
tion of  the  pinna. 

The  Middle  temporal  branch  passes  through  an  opening  in  the 
temporal  fascia  immediately  above  the  zygoma,  and  supplies  the 
temporal  muscle  inosculating  with  the  deep  temporal  arteries. 

11.  The  Internal  Maxillary  Artery,  the  other  terminal  branch 
of  the  external  carotid,  has  next  to  be  examined. 

Dissection. — The  Internal  maxillary  artery  passes  inwards  behind 
the  neck  of  the  lower  jaw  to  the  deep  structures  in  the  face ;  we 
require,  therefore,  to  remove  several  parts  for  the  purpose  of  seeing 
it  completely.  To  obtain  a  good  view  of  the  vessel,  the  zygoma 
should  be  sawn  across  in  front  of  the  external  ear,  and  the  malar 
bone  near  to  the  orbit.  Turn  down  the  zygomatic  arch  with  the 
masseter  muscle.  In  doing  this,  a  small  artery  and  nerve  will  be 
seen  crossing  the  sigmoid  arch  of  the  lower  jaw,  and  entering  the 
masseter  muscle  (the  masseteric).  Cut  away  the  tendon  of  the  tem- 
poral muscle  from  its  insertion  into  the  coronoid  process,  and  turn  it 
upwards  towards  its  origin ;  some  vessels  will  be  seen  entering  its 
under  surface ;  these  are  the  deep  temporal.  Then  saw  the  ramus 
of  the  jaw  across  its  middle,  and  dislocate  it  from  its  articulation 
with  the  temporal  bone.  Be  careful  in  doing  this  to  carry  the  blade 
of  the  knife  close  to  the  bone,  lest  any  branches  of  nerves  should 
be  injured.  Next  raise  this  portion  of  bone,  and  with  it  the  external 
pterygoid  muscle.  The  artery,  together  with  the  deep  branches  of 
the  inferior  maxillary  nerve,  will  be  seen  lying  upon  the  pterygoid 
muscles.  These  are  to  be  carefully  freed  of  fat  and  cellular  tissue, 
and  then  examined. 

This  artery  (fig.  103,  No.  12)  commences  in  the  substance  of  the 
parotid  gland,  opposite  the  meatus  auditorius  externus,  it  passes  in 
the  first  instance  horizontaUv  forwards  behind  the  neck  of  the  lower 


276  INTERNAL  MAXILLARY  ARTERY. 

jaw ;  next,  curves  around  the  lower  border  of  the  external  pterygoid 
muscle  near  its  origin,  and  ascends  obliquely  forwards  upon  the 
outer  side  of  that  muscle ;  it  then  passes  between  the  two  heads  of 
the  external  pterygoid  and  enters  the  pterygo-maxillary  fossa.  Occa- 
sionally it  passes  between  the  two  pterygoid  muscles,  without  appear- 
ing on  the  outer  surface  of  the  external  pterygoid.  In  consideration 
of  its  course  this  artery  may  be  divided  into  three  portions:  maxillary, 
pterygoid,  and  spheno-maxillary. 

Relations. — The  Maxillary  portion  is  situated  between  the  ramus 
of  the  jaw  and  the  internal  lateral  ligament,  lying  parallel  with  the 
auricular  nerve  ;  the  pterygoid  portion  between  the  external  ptery- 
goid muscle,  and  the  masseter  and  temporal  muscle.  The  pterygo- 
maxillary  portion  lies  between  the  two  heads  of  the  external  ptery- 
goid muscle,  and  in  the  spheno-maxillary  fossa  is  in  relation  with 
Meckel's  ganglion. 

Branches. 

Tympanic, 
nr     -1,  J-  J  Inferior  dental, 

Maxillary  pai^tion       ^  ^^^^^.-^  meningea  magna, 

Arteria  meningea  parva. 

Deep  temporal  branches. 
External  pterygoid. 
Pterygoid  portion  .     <^  Internal  pterygoid, 
Masseteric, 
Buccal. 

Superior  dental, 
Infra-orbital, 
Pterygo-maxillary      )  Pterygo-palatine, 
portion  j  Spheno-palatine, 

Posterior  palatine. 
Vidian. 

The  Tympanic  branch  is  small  and  not  likely  to  be  seen  in  an 
ordinary  dissection  ;  it  is  distributed  to  the  temporo-maxillary  articu- 
lation and  meatus,  and  passes  into  the  tympanum  through  the  fissura 
Glaseri. 

The  Inferior  dental  descends  to  the  dental  foramen,  and  enters 
the  canal  of  the  lower  jaw  in  company  with  the  dental  nerve. 
Opposite  the  bicuspid  teeth  it  divides  into  two  branches,  one  of 
which  is  continued  onwards  within  the  bone  as  far  as  the  symphysis, 
to  supply  the  incisor  teeth,  while  the  other  escapes  with  the  nerve 
at  the  mental  foramen,  and  anastomoses  with  the  inferior  labial  and 
submental  branch  of  the  facial.  It  supplies  the  teeth  of  the  lower 
jaw,  sending  small  branches  along  the  canals  in  their  roots. 

The  Arteria  meningea  magna  ascends  behind  the  temporo-maxil- 
lary articulation  to  the  foramen  spinosum  in  the  spinous  process  of 
the  sphenoid  bone,  and  entering  the  cranium  divides  into  an  anterior 
and  a  posterior  branch.     The  anterior  branch  crosses  the  great  ala 


INTERNAL  MAXILLARY  ARTERY.  277 

of  the  sphenoid  to  the  groove  or  canal  in  the  anterior  inferior  angle 
of  the  parietal  bone,  and  divides  into  branches,  v^hich  ramify  upon 
the  external  surface  of  the  dura  mater,  and  anastomose  with  corre- 
sponding branches  from  the  opposite  side.  The  posterior  branch 
crosses  the  squamous  portion  of  the  temporal  bone,  to  the  posterior 
part  of  the  dura  mater  and  cranium.  The  branches  of  the  arteria 
meningea  magna  are  distributed  chiefly  to  the  bones  of  the  skull ; 
and  in  the  middle  fossa  it  sends  a  small  branch  through  the  hiatus 
Fallopii  to  the  facial  nerve. 

The  Meningea  parva  is  a  small  branch  which  ascends  to  the 
foramen  ovale,  and  passes  into  the  skull  to  be  distributed  to  the 
Casserian  ganglion  and  dura  mater.  It  gives  off  a  small  branch  to 
the  nasal  fossae  and  soft  palate. 

The  Muscular  branches  are  distributed,  as  their  names  imply,  to 
the  five  muscles  of  the  maxillary  region ;  the  temporal  branches  are 
two  in  number. 

The  Superior  dental  artery  is  given  off  from  the  internal  maxil- 
lary, just  as  that  vessel  is  about  to  make  its  turn  into  the  spheno- 
maxillary fossa.  It  descends  upon  the  tuberosity  of  the  superior 
maxillary  bone,  and  sends  its  branches  through  several  small  fora- 
mina to  supply  the  posterior  teeth  of  the  upper  jaw,  and  the  antrum. 
The  terminal  branches  are  continued  forwards  upon  the  alveolar 
process,  to  be  distributed  to  the  gums  and  to  the  sockets  of  the 
teeth. 

The  Infra-orbital  would  appear,  from  its  size,  to  be  the  proper 
continuation  of  the  artery.  It  runs  along  the  infra-orbital  canal 
with  the  superior  maxillary  nerve,  sending  branches  into  the  orbit 
and  downwards  through  canals  in  the  bone,  to  supply  the  mucous 
lining  of  the  antrum  and  the  teeth  of  the  upper  jaw,  and  escapes 
from  the  infra-orbital  foramen.  The  branch  which  supplies  the  in- 
cisor teeth  is  the  anterior  dental  artery ;  on  the  face  it  inosculates 
with  the  facial  and  transverse  facial  arteries. 

The  Pterygo-palatine  is  a  small  branch  which  passes  through  the 
pterygo-palatine  canal,  and  supplies  the  upper  part  of  the  pharynx 
and  Eustachian  tube. 

The  Spheno-palatine,  or  nasal,  enters  the  superior  meatus  of  the 
nose  through  the  spheno-palatine  foramen  in  company  with  the  nasal 
branches  of  Meckel's  ganglion,  and  divides  into  two  branches  ;  one 
of  which  is  distributed  in  the  mucous  membrane  of  the  septum,  while 
the  other  supplies  the  mucous  membrane  of  the  lateral  wall  of  the 
nares,  together  with  the  sphenoid  and  ethmoid  cells. 

The  Posterior  palatine  artery  descends  along  the  posterior  pala- 
tine canal,  in  company  with  the  posterior  palatine  branches  of 
Meckel's  ganglion,  to  the  posterior  palatine  foramen  ;  it  then  curves 
forwards  lying  in  a  groove  upon  the  bone,  and  is  distributed  to  the 
palate,  while  in  the  posterior  palatine  canal  it  sends  a  small  branch 
backwards,  through  the  small  posterior  palatine  foramen  to  supply 
the  soft  palate,  and  anteriorly  it  supplies  a  branch  to  the  anterior 
palatine  canal,  which  reaches  the  nares  and  inosculates  with  the 
branches  of  the  spheno-palatine  artery. 


278  IjVTErnal  carotid  artery. 

The  Vidian  branch  passes  backwards  along  the  pterygoid  canal, 
and  is  distributed  to  the  sheath  of  the  Vidian  nerve,  and  to  the  Eus- 
tachian tube. 

INTERNAL  CAROTID  ARTERY. 

The  internal  carotid  artery  curves  slightly  outwards  from  the 
bifurcation  of  the  common  carotid,  and  then  ascends  nearly  perpen- 
dicularly through  the  maxillo-pharyngeal  space*  to  the  carotid  fora- 
men in  the  petrous  bone.  It  next  passes  inioards  along  the  carotid 
c^iidX,  forioards  by  the  side  of  the  sella  turcica,  and  upwards  by  the 
anterior  clinoid  process,  where  it  pierces  the  dura  mater  and  divides 
into  three  terminal  branches.  The  course  of  this  artery  is  remark- 
able from  the  number  of  angular  curves  which  it  forms  ;  one  or  two 
of  these  flexures  are  sometimes  seen  in  the  cervical  portion  of  the 
vessel  near  to  the  base  of  the  skull ;  and  by  the  side  of  the  sella  tur- 
cica it  resembles  the  italic  letter  s,  placed  horizontally. 

Relations. — In  consideration  of  its  connections,  the  artery  is  divi- 
sible into  a  cervical,  petrous,  cavernous,  and  cerebral  portion.  The 
Cervical  portion  is  in  relation  'posteriorly  with  the  rectus  anticus 
major,  sympathetic  nerve,  pharyngeal  and  laryngeal  nerves  which 
cross  behind  it,  and  near  the  carotid  foramen  with  the  glosso-pharyn- 
geal,  pneumogastric  and  lingual  nerves,  and  partially  with  the  inter- 
nal jugular  vein.  Internally  it  is  in  relation  with  the  side  of  the 
pharynx,  the  tonsil,  and  the  ascending  pharyngeal  artery.  Externally 
with  the  internal  jugular  vein,  glosso-pharyngeal,  pneumogastric, 
and  lingual  nerves,  and  in  front  with  the  stylo-glossus,  and  stylo- 
pharyngeus  muscle,  glosso-pharyngeal  nerve,  and  parotid  gland. 

Plan  of  the  relations  of  the  cervical  portion  of  the  internal  carotid 
artery. 

In  Front. 
Parotid  gland, 
Stylo-glossus  muscle, 
Stylo-pharyngeus  muscle, 
Glosso-pharyngeal  nerve. 


Internally, 

P^^'^y,"'''  I  Internal 

i°"^'''  ,  Carotid  Artery. 

Ascendmg   pharyn-  ' 

geal  artery. 


Externally, 
Jugular  vein, 
Glosso-pharyngeal, 
Pneumogastric, 
Lingual  nerve. 


Behind, 
Superior  cervical  ganglion, 
Pneumogastric  nerve, 
Glosso-pharyngeal, 
Pharyngeal  nerve, 
Superior  laryngeal  nerve. 
Sympathetic  nerve, 
Rectus  anticus  major. 


The  Petrous  portion  is  separated  from  the  bony  wall  of  the  carotid 
canal  by  a  lining  of  dura  mater ;  it  is  in  relation  with  the  carotid 
plexus,  and  is  covered  in  by  the  Casserian  ganglion. 

*  For  tlie  boundaries  of  this  space  bcc  page  IGG. 


INTERNAL  CAROTID  ARTERY.  279 

The  Cavernous  'portion  is  situated  in  the  inner  wall  of  the  caver- 
nous sinus,  and  is  in  relation  by  its  outer  side  with  the  lining  mem- 
brane of  the  sinus,  the  sixth  nerve,  and  the  ascending  branches  of 
the  carotid  plexus.  The  third,  fourth,  and  ophthalmic  nerves  are 
placed  in  the  outer  wall  of  the  cavernous  sinus,  and  are  separated 
from  the  artery  by  the  lining  membrane  of  the  sinus. 

The  Cerebral  portion  of  the  artery  is  enclosed  in  a  sheath  of  the 
arachnoid,  and  is  in  relation  with  the  optic  nerve.  At  its  point  of 
division  it  is  situated  in  the  fissure  of  Sylvius. 

Branches. — The  cervical  portion  of  the  internal  carotid  gives  oif 
no  branches :  from  the  other  portions  are  derived  the  following : — 

Tympanic, 

Anterior  meningeal. 

Ophthalmic, 

Anterior  cerebral. 

Middle  cerebral. 

Posterior  communicating, 

Choroidean. 

The  Tympanic  is  a  small  branch  which  enters  the  tympanum 
through  a  minute  foramen  in  the  carotid  canal. 

The  Anterior  meningeal  is  distributed  to  the  dura  mater  and  Cas- 
serian  ganglion. 

The  Ophthalmic  artery  arises  from  the  cerebral  portion  of  the  in- 
ternal carotid,  and  enters  the  oi'bit  through  the  foramen  opticum, 
immediately  to  the  outer  side  of  the  optic  nerve.  It  then  crosses 
the  optic  nerve  to  the  inner  wall  of  the  orbit,  and  runs  along  the 
lower  border  of  the  superior  oblique  muscle,  to  the  inner  angle  of 
the  eye,  where  it  divides  into  two  terminal  branches,  the  frontal  and 
nasal. 

Branches. — The  branches  of  the  ophthalmic  artery  may  be 
arranged  into  two  groups : — first,  those  distributed  to  the  orbit  and 
surrounding  parts ;  and  secondly,  those  which  supply  the  muscles 
and  globe  of  the  eye.     They  are — 

First  Group.  Second  Group. 

Lachrymal,  Muscular, 

Supra-orbital,  Anterior  ciliary, 

Posterior  ethmoidal.  Ciliary  short  and  long, 

Anterior  ethmoidal.  Centralis  retinae. 

Palpebral, 
Frontal, 
Nasal. 

The  Lachrymal  is  the  first  branch  of  the  ophthalmic  artery,  and 
is  usually  given  off  immediately  before  that  artery  enters  the  optic 
foramen.  It  follows  the  course  of  the  lachrymal  nerve,  along  the 
upper  border  of  the  external  rectus  muscle,  and  is  distributed  to  the 


280  OPHTHALMIC  ARTERY. 

lachrymal  gland.  The  small  branches  which  escape  from  the  gland 
supply  the  conjunctiva  and  upper  eyelid.  The  lachrymal  artery 
gives  off  a  malar  branch,  which  passes  through  the  malar  bone  into 
the  temporal  fossa  and  inosculates  with  the  deep  temporal  arteries, 
while  some  of  its  branches  become  subcutaneous  on  the  cheek  and 
anastomose  with  the  transverse  facial. 

The  Supra-orbital  artery  follows  the  course  of  the  frontal  nerve, 
resting  on  the  levator  palpebrse  muscle  :  it  passes  through  the  supra- 
orbital foramen,  and  divides  into  a  superficial  and  deep  branch  which 
are  distributed  to  the  muscles  and  integument  of  the  forehead  and 
to  the  pericranium.  At  the  supra-orbital  foramen  it  sends  a  branch 
inwards  to  the  diploe. 

The  Ethmoidal  arteries,  posterior  and  anterior,  pass  through  the 
ethmoidal  foramina,  and  are  distributed  to  the  falx  cerebri  and  to 
the  ethmoidal  cells  and  nasal  fossss.  The  latter  accompanies  the 
nasal  nerve. 

The  Palpebral  arteries,  superior  and  inferior,  are  given  off  from 
the  ophthalmic,  near  to  the  inner  angle  of  the  orbit ;  they  encircle 
the  eyelids,  forming  a  superior  and  inferior  arch  near  to  the  borders 
of  the  lids,  between  the  orbicularis  palpebrarum  and  tarsal  cartilage. 
At  the  outer  angle  of  the  eyelids  the  superior  palpebral  inosculates 
with  the  orbital  branch  of  the  temporal  artery.  The  inferior  palpe- 
bral artery  sends  a  branch  to  the  nasal  duct. 

The  Frontal  artery,  one  of  the  terminal  branches  of  the  ophthalmic, 
'emerges  from  the  orbit  at  its  inner  angle,  and  ascends  along  the 
middle  of  the  forehead.  It  is  distributed  to  the  integument,  muscles, 
and  pericranium. 

The  JVasal  artery,  the  other  terminal  branch  of  the  ophthalmic, 
passes  out  of  the  orbit  above  the  tendo  oculi,  and  divides  into  two 
branches  ;  one  of  which  inosculates  with  the  angular  artery,  while 
the  other,  the  dorsalis  nasi,  runs  along  the  ridge  of  the  nose  and  is 
distributed  to  its  entire  surface.  The  nasal  artery  sends  a  small 
branch  to  the  lachrymal  sac. 

The  Muscular  branches,  usually  two  in  number,  superior  and 
inferior,  supply  the  muscles  of  the  orbit;  and  upon  the  anterior 
aspect  of  the  globe  of  the  eye  give  off  the  anterior  ciliary  arteries, 
which  pierce  the  sclerotic  near  its  margin  of  connection  with  the 
cornea,  and  are  distributed  to  the  iris.  It  is  the  congestion  of  these 
vessels  that  gives  rise  to  the  vascular  zone  around  the  cornea  in 
iritis. 

The  Ciliary  arteries  are  divisible  into  three  groups, — short,  long, 
and  anterior. 

The  Short  ciliary  are  very  numerous ;  they  pierce  the  sclerotic 
around  the  entrance  of  the  optic  nerve,  and  supply  the  choroid  coat 
and  ciliary  processes.  The  long  ciliary,  two  in  number,  pierce  the 
sclerotic  upon  opposite  sides  of  the  globe  of  the  eye,  and  pass  for- 
wards between  it  and  the  choroid  to  the  iris.  They  form  an  arterial 
circle  around  the  circumference  of  the  iris  by  inosculating  with 
each  other,  and  from  this  circle  branches  are  given  off  which  ramify 


SUBCLAVIAN  ARTERY,  281 

in  the  substance  of  the  iris,  and  form  a  second  circle  around  the 
pupil.  The  anterior  ciliary  are  branches  of  the  muscular  arteries ; 
they  terminate  in  the  great  arterial  circle  of  the  iris. 

The  Centralis  retince  artery  pierces  the  optic  nerve  obliquely, 
and  passes  forwards  in  the  centre  of  its  cylinder  to  the  retina, 
where  it  divides  into  branches,  which  ramify  in  the  inner  layer  of 
that  membrane.  It  supplies  the  retina,  hyaloid  membrane,  and 
zonula  ciliaris  ;  and,  by  means  of  a  branch  sent  forwards  through 
the  centre  of  the  vitreous  humour  in  a  tubular  sheath  of  the  hyaloid 
membrane,  the  capsule  of  the  lens. 

The  Anterior  cerebral  artery  passes  forwards  in  the  great  longi- 
tudinal fissure  between  the  two  hemispheres  of  the  brain;  then 
curves  backwards  along  the  corpus  callosum  to  its  posterior  extre- 
mity. It  gives  branches  to  the  olfactory  and  optic  nerves,  to  the 
under  surface  of  the  anterior  lobes,  the  third  ventricle,  the  corpus 
callosum,  and  the  inner  surface  of  the  hemispheres.  The  two  ante- 
rior cerebral  arteries  are  connected  soon  after  their  origin  by  a 
short  anastomosing  trunk,  the  anterior  communicating. 

The  Middle  cerebral  artery,  larger  than  the  preceding,  passes  out- 
wards along  the  fissure  of  Sylvius,  and  divides  into  three  principal 
branches,  which  supply  the  anterior  and  middle  lobes,  and  the  island 
of  Reil.  Near  to  its  origin  it  gives  off  the  numerous  small  branches 
which  enter  the  substantia  perforata,  to  be  distributed  to  the  corpus 
striatum. 

The  Posterior  Communicating  artery,  very  variable  in  size,  some- 
times double,  and  sometimes  altogether  absent,  passes  backwards 
and  inosculates  with  the  posterior  cerebral,  a  branch  of  the  basilar 
artery.  Occasionally  it  is  so  large  as  to  take  the  place  of  the  pos- 
terior cerebral  artery. 

The  Choroidean  is  a  small  branch  which  is  given  off  from  the 
internal  carotid,  near  to  the  origin  of  the  posterior  communicating 
artery,  and  passes  beneath  the  edge  of  the  middle  lobe  of  the  brain 
to  enter  the  descending  cornu  of  the  lateral  ventricle.  It  is  distri- 
buted to  the  choroid  plexus,  and  to  the  walls  of  the  middle  cornu. 

SUBCLAVIAN  ARTERY. 

The  Subclavian  artery,  on  the  right  side,  arises  from  the  arteria 
innominata,  opposite  the  sterno-clavicular  articulation,  and  on  the 
left,  from  the  arch  of  the  aorta.  The  right  is  consequently  shorter 
than  the  left,  and  is  situated  nearer  to  the  anterior  wall  of  the  chest ; 
it  is  also  somewhat  greater  in  diameter,  from  being  a  branch  of  a 
branch,  in  place  of  a  division  from  the  main  trunk. 

The  course  of  the  subclavian  artery  is  divisible,  for  the  sake  of 
precision  and  surgical  observation,  into  three  portions.  The  first 
portions  of  the  right  and  left  arteries  differ  in  their  course  and  rela- 
tions in  correspondence  with  their  dissimilarity  of  origin.  The  other 
two  portions  are  precisely  alike  on  both  sides. 

The  first  portion,  on  the  rig/it  side,  ascends  obliquely  outwards  to 
the  inner  border  of  the  scalenus  anticus.     On  the  left  side  it  ascends 

3G 


282 


SUBCLAVIAN  ARTERY RELATIONS. 


perpendicularly  to  the  inner  border  of  that  muscle.  The  second 
portion  curves  outwards  behind  the  scalenus  anticus ;  and  the  third 
portion  passes  downwards  and  outwards  beneath  the  clavicle,  to  the 
lower  border  of  the  jfirst  rib,  where  it  becomes  the  axillary  artery. 

Relations. — The  first  portion,  on  the  rigid  side,  is  in  relation  in 
frotit  with  the  internal  jugular  and  subclavian  vein  at  their  point  of 
junction,  and  is  crossed  by  the  pneumogastric  nerve,  cardiac  nerves, 
and  phrenic  nerve.  Behind  and  beneath  it  is  invested  by  the  pleura, 
is  crossed  by  the  right  recurrent  laryngeal  nerve  and  vertebral  vein, 
and  is  in  relation  with  the  transverse  process  of  the  seventh  cervical 
vertebra.  The  first  portion  on  the  left  side  is  in  relation  in  front  with 
the  pleura,  the  vena  innominata,  the  pneumogastric  and  phrenic 
nerves  (which  lie  parallel  to  it),  and  the  left  carotid  artery.  To  its 
ijiner  side  is  the  oesophagus ;  to  its  outer  side  the  pleura ;  and  hehiiid, 
the  thoracic  duct,  longus  colli,  and  vertebral  column. 

Plan  of  the  relations  oUhe  first  portion  of  the  Right  Subclavian  Artery. 

In  Front. 
Internal  jugular  vein, 
Subclavian  vein, 
Pneumogastric  nerve, 
Cardiac  nerves, 
Phrenic  nerve. 


Behind  and  beneath. 
Pleura, 

Recurrent  laryngeal  nerve. 
Vertebral  vein, 
Transverse  process  of  7th  cervical  vertebra. 

Plan  of  the  relations  of  the  first  portion  of  the  Left  Subclavian  Artery. 

In  Front. 
Pleura, 

Vena  innominata, 
Pneumogastric  nerve, 
Phrenic  nerve, 
Left  carotid  artery. 


Inner  Side. 
(Esophagus. 


Left  Subclavian  Artery. 


Outer  Side. 
Pleura. 


Behind. 
Thoracic  duct, 
Longus  colli, 
Vertebral  column. 

The  Second  portion  is  situated  between  the  two  scaleni,  and  is 
supported  by  the  margin  of  the  first  rib.  The  scalenus  anticus 
separates  it  from  the  subclavian  vein  and  j)hrenic  nerve.  Behind  it 
is  in  relation  with  the  brachial  plexus. 

The  7'hyroid  portion  is  in  relation,  in  front  with  the  subclavian  vein 
and  subclavius  muscle;  behind  w'lih  the  brachial  plexus  and  scalenus 
posticus;  below  with  the  first  rib;  and  above  with  the  supra-scapular 
artery  and  platysma. 


VERTEBRAL  ARTERY, 


283 


Plan  of  the  relations  of  the  third  portion  of  the  Subclavian  Artery, 


Above. 
Supra-scapular  artery, 
Platysma  myoides. 


In  Front. 
Subclavian  vein, 
Subclavius. 


Subclavian  Artery, 
Third  portion. 


Behind. 
Brachial  plexus, 
Scalenus  posticus. 


Below. 
First  rib. 


Thyroid  axis, 


Fig.  104.t 


Branches. — The  greater  part  of  the  branches  of  the  subclavian 
are  given  off  from  the  artery  before  it  arrives  at  the  margin  of  the 
first  rib.  The  profunda  cervicis  and  superior  intercostal  frequently 
encroach  upon  the  second  portion,  and  not  unfrequently  a  branch  or 
branches  may  be  found  proceeding  from  the  third  portion. 

The  primary  branches  are  five  in  number,  the  three  first  being 
ascending,  and  the  latter  descending ;  they  are  the — 

Vertebral, 

Inferior  thyroid. 
Supra-scapular,* 
Posterior  scapular, 
Superficialis  cervicis. 
Profunda  cervicis, 
Superior  intercostal, 
Internal  mammary. 
The  Vertebral  Artery  is  the  first  and  the  largest  of  the  branches 
of  the    subclavian   artery;    it   ascends 
through  the  foramina  in  the  transverse 
processes  of  all  the  cervical  vertebrae, 
excepting  the  last ;    then  winds  back- 
wards around  the  articulating  process 
of  the    atlas ;    and   piercing   the    dura 
mater    enters    the    skull    through    the 
foramen  magnum.      The  two  arteries 
unite  at  the  lower  border  of  the  pons 
Varolii,  to  form  the  basilar  artery.     In 
the  foramina  of  the  transverse  processes 
of  the  vertebrae  the  artery  lies  in  front 
of  the  cervical  nerves. 

Dr.  John  DavyJ  has  observed  that, 
when  the  vertebral  arteries  differ  in 
size,  the  left  is  generally  the  larger : 
thus  in  ninety-eight  cases  he  found  the 

*  This  is  usually  described  as  arising'  from  the  axillary,  but  I  have  most  frequently 
found  it  to  arise  from  the  subclavian. — G. 

t  The  branches  of  the  right  subclavian  artery.  1.  The  arteria  innominata.  2. 
The  right  carotid.  3.  Tlic  first  portion  of  the  subclavian  artery.  4.  The  second  por- 
tion, o.  The  tiiird  portion.  6.  The  vertebral  artery.  7.  The  inferior  thyroid.  8. 
The  thyroid  axis.  9.  The  superficialis  cervicis.  10.  The  profunda  cervicis.  11.  Tlie 
posterior  scapular  or  transversalis  colli.  12.  The  supra-scapular,  13.  Tlie  internal 
mammary  artery.     14.  The  superior  intercostal. 

t  Edinburgh  Medical  and  Surgical  Journal,  1839. 


284  BASILAR  ARTERY BRANCHES. 

left  vertebral  the  larger  twenty-six  times,  and  the  right  only  eight. 
In  the  same  number  of  cases  he  found  a  small  band  stretching 
across  the  cylinder  of  the  basilar  artery,  near  the  junction  of  the 
two  vertebral  arteries,  seventeen  times,  and  in  a  few  instances  a 
small  communicating  trunk  between  the  two  vertebral  arteries  pre- 
viously to  their  union.  I  have  several  times  seen  this  communicating 
branch,  and  have  a  preparation  now  before  me .  in  which  it  is  ex- 
hibited. 

The  Basilar  Artery,  so  named  from  its  position  at  the  base  of 
the  brain,  runs  forwards  to  the  anterior  border  of  the  pons  Varolii, 
where  it  divides  into  four  ultimate  branches,  two  to  either  side. 

Brandies. — The  branches  of  the  vertebral  and  basilar  arteries  are 
tlie  following : — 

Lateral  spinal, 
Posterior  meningeal, 
Vertebral,  ^  Anterior  spinal. 
Posterior  spinal, 
Inferior  cerebellar. 

(  Transverse, 
Basilar^      <  Superior  cerebellar, 
(  Posterior  cerebral. 

The  Lateral  spinal  branches  enter  the  intervertebral  foramina, 
and  are  distributed  to  the  spinal  cord  and  to  its  membranes.  Where 
the  vertebral  artery  curves  around  the  articular  process  of  the  atlas, 
it  gives  ofl'  several  muscular  branches. 

The  Posterior  meningeal  are  one  or  two  small  branches,  which 
enter  the  cranium  through  the  foramen  magnum,  to  be  distributed 
to  the  dura  mater  of  the  cerebellar  fossee,  and  to  the  falx  cerebelli. 
One  branch,  described  by  Soemmering,  passes  into  the  cranium 
along  the  first  cervical  nerve. 

The  Anterior  spinal  is  a  small  branch  which  unites  with  its  fellow 
of  the  opposite  side,  on  the  front  of  the  medulla  oblongata.  The 
artery  formed  by  the  union  of  these  two  vessels  descends  along  the 
anterior  aspect  of  the  spinal  cord,  to  which  it  distributes  branches. 

The  Posterior  spinal  winds  around  the  medulla  oblongata  to  the 
posterior  aspect  of  the  cord,  and  descends  on  either  side,  communi- 
cating very  freely  with  the  spinal  branches  of  the  intercostal  and 
lumber  arteries.  Near  its  commencement  it  sends  a  branch  upwards 
to  the  fourth  ventricle. 

The  Inferior  cerebellar  arteries  wind  around  the  upper  part  of  the 
medulla  oblongata  to  the  under  surface  of  the  cerebellum,  to  which 
they  are  distributed.  They  pass  between  the  filaments  of  origin  of 
the  hypoglossal  nerve  in  their  course,  and  anastomose  with  the 
superior  cerebellar  arteries. 

The  Transverse  branches  of  the  basilar  artery  supply  the  pons 
Varolii,  and  adjacent  parts  of  the  brain.     One  of  these  branches, 


THYROID  AXIS BRANCHES.  285 

larger  than  the  rest,  passes  along  the  crus  cerebelli  to  be  distributed 
to  the  anterior  border  of  the  cerebellum.  This  may  be  called  the 
middle  cerebellar  artery. 

The  Superior  cerebellar  arteries,  two  of  the  terminal  branches  of 
the  basilar,  wind  around  the  crus  cerebri  on  each  side  in  relation 
with  the  fourth  nerve,  and  are  distributed  to  the  upper  surface  of 
the  cerebellum  inosculating  with  the  inferior  cerebellar.  This 
artery  gives  off  a  small  branch  which  accompanies  the  seventh 
pair  of  nerves  into  the  meatus  auditorius  internus. 

The  Posterior  cerebral  arteries,  the  other  two  terminal  branches 
of  the  basilar,  wind  around  the  crus  cerebri  at  each  side,  and  are 
distributed  to  the  posterior  lobes  of  the  cerebrum.  They  are  sepa- 
rated from  the  superior  cerebellar  artery,  near  the  origin,  by  the 
third  pair  of  nerves,  and  are  in  close  relation  with  the  fourth  pair 
in  their  course  around  the  crura  cerebrL  Anteriorly,  near  their 
origin,  they  give  off  a  tuft  of  small  vessels,  which  enter  the  locus 
perforatus,  and  they  receive  the  posterior  communicating  arteries 
from  the  internal  carotid.  They  also  send  a  branch  to  the  velum 
interpositum  and  plexus  choroides. 

The  communications  established  between  the  anterior  cerebral 
arteries  in  front,  and  the  internal  carotids  and  posterior  cerebral 
arteries  behind,  by  the  communicating  arteries,  constitute  the  circle 
of  Willis.  This  remarkable  communication  at  the  base  of  the 
brain  is  formed  by  the  anterior  communicating  branch,  anterior 
cerebrals,  and  internal  carotid  arteries  in  front,  and  by  the  posterior 
communicating,  posterior  cerebrals,  and  basilar  artery  behind. 

The  Thyroid  Axis  is  a  short  trunk  which  divides  almost  imme- 
diately after  its  origin  into  four  branches,  some  of  which  are  occa- 
sionally branches  of  the  subclavian  artery  itself. 

The  I\FERioR  Thyroid  Artery  ascends  obliquely  in  a  serpentine 
course  behind  the  sheath  of  the  carotid  vessels,  to  the  inferior  part 
of  the  thyroid  gland,  to  which  it  is  distributed,  and  sends  branches 
to  the  trachea,  lower  part  of  the  larynx,  and  oesophagus.  It  is  in 
relation  with  the  middle  cervical  ganglion  of  the  sympathetic, 
which  lies  in  front  of  it. 

The  Supra-scapular  artery  (transversalis  humeri)  passes  ob- 
liquely outwards  behind  the  clavicle,  and  over  the  ligament  of  the 
supra-scapular  notch,  to  the  supra-spinatus  fossa.  It  crosses  in  its 
course  the  scalenus  anticus  muscle,  phrenic  nerve  and  subclavian 
artery,  is  distributed  to  the  muscles  on  the  dorsum  of  the  scapula, 
and  inosculates  with  the  posterior  scapular,  and  beneath  the  acro- 
mion process  with  the  dorsal  branch  of  the  subscapular  artery. 
At  the  supra-scapular  notch  it  sends  a  large  branch  to  the  trape- 
zius muscle.  The  supra-scapular  artery  is  not  unfrequently  a 
branch  of  the  subclavian. 

The  Posterior  Scapular  Artery  (transversalis  colli)  passes 
transversely  across  the  subclavian  triangle  at  the  root  of  the  neck, 
to  the  superior  angle  of  the  scapula.  It  then  descends  along  the 
posterior  border  of  that  bone  to  its  inferior  angle,  where  it  inoscu- 


286 


CIRCLE  OF  WILLIS. 


lates  with  the  subscapular  artery,  a  branch  of  the  axillary.  In  its 
course  across  the  neck  it  passes  in  front  of  the  scalenus  anticus, 
and  across  the  brachial  plexus;  in  the  rest  of  its  course  it  is  covered 
in  by  the  trapezius,  levator  anguli  scapulae,  rhomboideus  minor,  and 
rhomboideus  major  muscles.  Sometimes  it  passes  behind  the 
scalenus  anticus,  and  between  the  nerves  wliich  constitute  the 
brachial  plexus.  This  artery,  which  is  very  irregular  in  its  origin, 
proceeds  more  frequently  from  the  third  portion  of  the  subclavian 
artery  than  from  the  first. 

Fiff.  105.* 


The  posterior  scapular  gives  branches  to  the  neck,  and  opposite 
the  angle  of  the  scapula  inosculates  with  the  profunda  cervicis.  It 
supplies  the  muscles  along  the  posterior  border  of  the  scapula,  and 
establishes  an  important  anastomotic  communication  between  the 
branches  of  the  external  carotid,  subclavian,  and  axillary  arteries. 

*  The  circle  of  Willis.  The  branches  of  tlie  arteries  have  references  only  on  one 
side,  on  account  of  their  symmetrical  distribution.  1.  The  vertebral  arteries.  2.  The 
two  anterior  spinal  branches  uniting  to  form  a  single  vessel.  3.  One  of  tlic  posterior 
spinal  arteries.  4.  The  posterior  meningeal.  5.  Tlie  inferior  cerebellar.  G.  The 
basilar  artery  giving  off  its  transverse  branches  to  either  side.  7.  The  superior  cere- 
bellar artery.  8.  The  posterior  cerebral.  9.  Tlic  posterior  communicating  branch  of 
the  internal  carotid.  10.  The  internal  carotid,  showing  tlie  curvatures  it  makes  witliin 
the  skull.  11.  The  ophthalmic  artery  divided  across.  12.  The  middle  cerebral  artery. 
13.  The  anterior  cerebral  arteries  connected  by,  14.  The  anterior  communicating 
artery. 


INTERNAL  MAMMARY  ARTERY.  287 

The  SuPERFiciALis  Cervicis  Artery  (cervicalis  anterior)  is  a  small 
vessel,  which  ascends  upon  the  anterior  tubercles  of  the  transverse 
processes  of  the  cervical  vertebrtE,  lying  in  the  groove  between 
the  scalenus  anticus  and  rectus  anticus  major.  It  is  distributed  to 
the  deep  muscles  and  glands  of  the  neck,  and.  sends  branches 
through  the  intervertebral  foramina  to  supply  the  spinal  cord  and 
its  membranes. 

The  Profunda  Cervicis  (cervicalis  posterior)  passes  backwards 
between  the  transverse  processes  of  the  seventh  cervical  and  first 
dorsal  vertebra,  and  then  ascends  the  back  part  of  the  neck, 
between  the  complexus  and  semi-spinalis  colli  muscles.  It  inoscu- 
lates above  with  the  princeps  cervicis  of  the  occipital  artery,  and 
below,  by  a  descending  branch,  with  the  posterior  scapular. 

The  Superior  Intercostal  Artery  descends  behind  the  pleura 
upon  the  necks  of  the  first  two  ribs,  and  inosculates  with  the  first 
aortic  intercostal.  It  gives  off  two  branches  which  supply  the  two 
first  intercostal  spaces. 

The  Internal  Mammary  Artery  descends  by  the  side  of  the 
sternum,  resting  upon  the  costal  cartilages,  to  the  diaphragm :  it 
then  pierces  the  anterior  fibres  of  the  diaphragm,  and  enters  the 
sheath  of  the  rectus,  where  it  inosculates  with  the  epigastric  artery, 
a  branch  of  the  external  iliac.  In  the  upper  part  of  its  course  it  is 
crossed  by  the  phrenic  nerve,  and  lower  down  lies  between  the 
triangularis  sterni  and  the  internal  intercostal  muscles. 

The  Branches  of  the  internal  mammary  are, — 

Anterior  intercostal. 

Mammary, 

Comes  nervi  phrenici, 

Mediastinal, 

Pericardiac, 

Musculo-phrenic. 

The  Anterior  intercostals  supply  the  intercostal  muscles  of  the 
front  of  the  chest,  and  inosculate  with  the  aortic  intercostal  arteries. 
Each  of  the  three  first  anterior  intercostals  gives  ofi"  a  large  branch 
to  the  mammary  gland,  which  anastomoses  freely  with  the  thoracic 
branches  of  the  axillary  artery ;  the  corresponding  branches  from 
the  remaining  intercostals  supply  the  integument  and  pectoralis 
major  muscle.  There  are  usually  two  anterior  intercostal  arteries 
in  each  space. 

The  Comes  nervi  phrenici  is  a  long  and  slender  branch  which 
accompanies  the  phrenic  nerve. 

The  mediastinal  and  fericardiac  branches  are  small  vessels  dis- 
tributed to  the  anterior  mediastinum,  the  thymus  gland,  and  peri- 
cardium. 

The  Musculo-phrenic  artery  winds  along  the  attachment  of  the' 
diaphragm  to  the  ribs,  supplying  that  muscle  and  sending  branches 
to  the  inferior  intercostal  spaces.     "  The  mammary  arteries,"  says 


288  AXILLARY  ARTERY. 

Dr.  Harrison,  "  are  remarkable  for  the  number  of  their  inosculations, 
and  for  the  distant  parts  of  the  arterial  system  which  they  serve  to 
connect.  They  anastomose  with  each  other,  and  their  inosculations, 
with  the  thoracic  aorta,  encircle  the  thorax.  On  the  parietes  of  this 
cavity  their  branches  connect  the  axillary  and  subclavian  arteries ; 
on  the  diaphragm  they  form  a  link  in  the  chain  of  inosculations  be- 
tween the  subclavian  artery  and  abdominal  aorta,  and  in  the  parietes 
of  the  abdomen  they  form  an  anastomosis  most  remarkable  for  the 
distance  between  those  vessels  which  it  serves  to  connect ;  namely, 
the  arteries  of  the  superior  and  inferior  extremities," 

Varieties  of  the  Subclavian  Arteries. — Varieties  in  these  arteries 
are  rare  ;  that  which  most  frequently  occurs  is  the  origin  of  the  right 
subclavian,  from  the  left  extremity  of  the  arch  of  the  aorta,  below 
the  left  subclavian  artery.  The  vessel,  in  this  case,  curves  behind 
the  oesophagus  and  right  carotid  artery,  and  sometimes  between  the 
oesophagus  and  trachea,  to  the  upper  border  of  the  first  rib,  on  the 
right  side  of  the  chest,  where  it  assumes  its  ordinary  course.  In  a 
case*  of  subclavian  aneurism  on  the  right  side,  above  the  clavicle, 
which  happened  during  the  present  summer,  Mr.  Liston  proceeded 
to  perform  the  operation  of  tying  the  carotid  and  subclavian  arteries 
at  their  point  of  division  from  the  innominata.  Upon  reaching  the 
point  where  the  bifurcation  should  have  existed,  he  found  that  there 
was  no  subclavian  artery.  With  that  admirable  self-possession 
which  distinguishes  this  eminent  surgeon  in  all  cases  of  emergency, 
he  continued  his  dissection  more  deeply,  towards  the  vertebral 
column,  and  succeeded  in  securing  the  artery.  It  was  ascertained 
after  death,  that  the  arteria  innominata  was  extremely  short,  and 
that  the  subclavian  was  given  off  within  the  chest  from  the  posterior 
aspect  of  its  trunk,  and  pursued  a  deep  course  to  the  upper  mar- 
gin of  the  first  rib.  In  a  preparation  which  was  shown  to  me  in 
Heidelberg  some  years  since  by  Professor  Tiedemann,  the  right 
subclavian  artery  arose  from  the  thoracic  aorta,  as  low  down  as 
the  fourth  dorsal  vertebra,  and  ascended  from  that  point  to  the 
border  of  the  first  rib.  Varieties  in  the  branches  of  the  subclavian 
are  not  unfrequent ;  the  most  interesting  is  the  origin  of  the  left 
vertebral,  from  the  arch  of  the  aorta,  of  which  I  possess  several 
preparations. 

AXILLARY  ARTERY. 

The  axillary  artery  forms  a  gentle  curve  through  the  middle  of  the 
axillary  space  from  the  lower  border  of  the  first  rib  to  the  lower 
border  of  the  latissimus  dorsi,  where  it  becomes  the  brachial. 

Relations. — After  emerging  from  beneath  the  margin  of  the  costo- 
coracoid  membrane,  it  is  in  relation  with  the  axillary  vein,  which 
lies  at  first  to  the  inner  side  and  then  in  front  of  the  artery.  Near 
the  middle  of  the  axilla  it  is  embraced  by  the  two  heads  of  the 
median  nerve,  and  is  covered  in  by  the  pectoral  muscles.  Upon  the 

*  This  caae  is  recorded  in  the  Lancet,  Vol.  I.  1839-40,  pp.  37  and  419. 


AXILLARY   ARTERY.  280 

inner  or  thoracic  side  it  is  in  relation,  first,  with  the  first  intercostal 
muscle ;  it  next  rests  upon  the  first  serration  of  the  serratus  magnus ; 
and  is  then  separated  from  the  chest  by  the  brachial  plexus  of  nerves. 
By  its  outer  or  humeral  side  it  is  at  first  separated  from  the  brachial 
plexus  by  a  triangular  cellular  interval ;  it  next  rests  against  the 
tendon  of  the  subscapularis  muscle  ;  and  thirdly  upon  the  coraco-bra- 
chialis  muscle. 

The  relations  of  the  axillary  artery  may  be  thus  arranged : — 
In  front.  Inner  or  thoracic  Side.       Outer  or  humeral  Side. 

Pectoralis  major,  First  intercostal  muscle,  Plexus  of  nerves, 
Pectoralis  minor.  First  serration  of  ser-  Tendon  of  sub- 
Pectoralis  major.         ratus  magnus,  ■  scapularis, 

Plexus  of  nerves.  Coraco-brachialis. 

Branches. — The  branches  of  the  Axillary  artery  are  seven  in 
number : — 

Thoracica  acromiahs, 
Superior  thoracic, 
Inferior  thoracic, 
Thoracica  axillaris, 
Subscapular, 
Circumflex  anterior. 
Circumflex  posterior. 

The  thoracica  acromialis  and  superior  thoracic  are  found  in  the 
triangular  space  above  the  pectoralis  minor. 

The  inferior  thoracic  and  thoracica  axillaris,  below  the  pecto- 
ralis minor. 

And  the  three  remaining  branches  below  the  lower  border  of  the 
subscapularis. 

The  Thoracica  acromialis  is  a  short  trunk  which  ascends  to  the 
space  above  the  pectoralis  minor  muscle,  and  divides  into  three 
branches, — thoracic,  which  is  distributed  to  the  pectoral  muscles 
and  mammary  gland;  acromial,  which  passes  outwards  to  the 
acromion,  and  inosculates  with  branches  of  the  supra-scapular 
artery ;  and  descending,  which  follows  the  interspace  between  the 
deltoid  and  pectorahs  major  muscles,  and  is  in  relation  with  the 
cephalic  vein. 

The  Superior  thoracic  (short),  very  frequently  arises  by  a  common 
trunk  with  the  preceding ;  it  runs  along  the  upper  border  of  the 
pectoralis  minor,  and  is  distributed  to  the  pectoral  muscles  and 
mammary  gland,  inosculating  with  the  intercostal  and  mammary 
arteries. 

The  Inferior  thoracic  (long  external  mammary)  descends  along 
the  lower  border  of  the  pectoralis  minor  to  the  side  of  the  chest.  It 
is  distributed  to  the  pectoralis  major  and  minor,  serratus  magnus, 
and  subscapularis  muscle,  to  the  axillary  glands  and  mammary 
gland ;  inosculating  with  the  superior  thoracic,  intercostal,  and 
mammary  arteries. 

37 


290 


BRANCHES  OF  THE  AXILLARY  ARTERY. 


Fig.  106.* 


The  Thoracica  axillaris  is  a  small  branch  distributed  to  the  plexus 

of  nerves  and  glands  in  the  axilla. 
It  is  frequently  derived  from  one  of 
the  other  thoracic  branches.    • 

The  Subscajndar  artery,  the  largest 
of  the  branches  of  the  axillary,  runs 
along  the  lower  border  of  the  subsca- 
pularis  muscle,  to  the  inferior  angle  of 
the  scapula,  where  it  inosculates  with 
the  posterior  scapular,  a  branch  of  the 
subclavian.  It  supphes,  in  its  course, 
the  muscles  on  the  under  surface,  and 
inferior  border  of  the  scapula,  and  the 
side  of  the  chest.  At  about  an  inch  and 
a  half  from  the  axillary,  it  gives  off 
a  large  branch,  the  dorsalis  scapulcs, 
which  passes  backwards  through  the 
triangular  space  bounded  by  the  teres 
minor,  teres  major,  and  scapular  head 
of  the  triceps,  and  beneath  the  infra- 
spinatus to  the  dorsum  of  the  scapula, 
■^  where  it  is  distributed,  inosculating 
\  with  the  supra-scapular  and  posterior 
;A     scapular  arteries. 

The  Cirmmjlex  arteries'wmdB.i'ound 

the  neck  of  the  humerus.  The  anterior 

very  small,  passes  beneath  the  coraco- 

brachialis     and    short    head    of    the 

biceps,   and   sends  a  branch    upwards  along  the   bicipital  groove 

to  supply  the  shoulder-joint. 

The  Posterior  circumjiex,  of  larger  size,  passes  backwards  through 
the  quadrangular  space  bounded  by  the  teres  minor  and  major,  the 
scapular  head  of  the  triceps  and  the  humerus,  and  is  distributed  to 
the  deltoid  muscle  and  joint.  Sometimes  this  artery  is  a  branch  of 
the  superior  profunda  of  the  brachial.  It  then  ascends  behind  the 
tendon  of  the  teres  major,  and  is  distributed  to  the  deltoid  without 
passing  through  the  quadrangular  space.  The  posterior  circumflex 
artery  sends  branches  to  the  shoulder-joint. 

*  The  axillary  and  brachial  artery,  with  their  branches.  ].  The  deltoid  muscle.  2. 
The  biceps.  3.  The  tendinous  process  given  off  from  the  tendon  of  the  biceps,  to  the 
deep  fascia  of  the  fore-arm.  It  is  this  process  which  separates  the  median  basilic 
vein  from  the  brachial  artery.  4.  The  outer  border  of  the  brachialis  anticus  muscle. 
5.  The  supinator  longus.  6.  The  coraco-brachialis.  7.  Tlio  middle  portion  of  tlie 
triceps  muscle.  8.  Its  inner  head.  9.  The  a,\illary  artery.  10.  The  brachial  artery  ; 
— a  dark  line  marks  the  limit  between  these  two  vessels.  11.  The  thoracica  acro- 
mialis  artery  dividing  into  its  three  branches ;  the  number  rests  upon  the  coracoid  pro- 
cess. 12.  The  superior  and  inferior  thoracic  arteries.  1.3.  The  scrratus  magnus  mus- 
cle, 14.  The  subscapular  artery.  The  posterior  circumflex  and  thoracica  axillaris 
branches  are  seen  in  the  figure  between  the  inferior  thoracic  and  subscapular.  The 
anterior  circumflex  is  observed,  between  the  two  heads  of  the  biceps,  crossing  the 
neck  of  the  humerus.     15.  The  superior  profunda  artery.     JG.  The  inferior  profunda. 

17.  The  anastomotica  magna  inosculating  inferiorly,  with  the  anterior  ulnar  recurrent. 

18.  The  termination  of  the  superior  profunda,  inosculating  with  the  radial  recurrent 
in  the  interspace  between  the  brachialis  anticus  and  supinator  longus. 


BRACHIAL  ARTERY BRANCHES. 


291 


Varieties  of  the  Axillary  Artery. — The  most  frequent  peculiarity 
of  this  kind  is  the  division  of  the  vessel  into  two  trunks  of  equal 
size :  a  muscular  trunk,  which  gives  off  some  of  the  ordinary  axil- 
lary branches  and  supplies  the  upper  arm,  and  a  continued  trunk, 
which  represents  the  brachial  artery.  The  next  most  frequent  variety 
is  the  high  division  of  the  ulnar  which  passes  down  the  arm  by  the 
side  of  the  brachial  artery,  and  superficially  to  the  muscles  proceed- 
ing from  the  inner  condyle,  to  its  ordinary  distribution  in  the  hand. 
In  this  course  it  Kes  immediately  beneath  the  deep  fascia  of  the  fore- 
arm, and  may  be  seen  and  felt  pulsating  beneath  the  integument. 
The  high  division  of  the  radial  from  the  axillary  is  rare.  In  one 
instance,  I  saw  the  axillary  artery  divide  into  three  branches  of 
nearly  equal  size,  which  passed  together  down  the  arm,  and  at  the  bend 
of  the  elbow  resolved  themselves  into  radial,  ulnar,  and  interosseous. 
But  the  most  interesting  variety,  both  in  a  physiological  and  surgical 
sense,  is  that  described  by  Dr.  Quain,  in  his  "  Elements  of  Anatomy." 
"  I  found  in  the  dissecting-room,  a  few  years  ago,  a  variety  not 
hitherto  noticed  :  it  was  at  first  taken  for  the  ordinary  high  division 
of  the  ulnar  artery.  The  two  vessels  descended  from  the  point  of 
division  at  the  border  of  the  axilla,  and  lay  parallel  with  one  another 
in  their  course  through  the  arm ;  but  instead  of  diverging,  as  is 
usual,  at  the  bend  of  the  elbow,  they  converged,  and  united  so  as  to 
form  a  short  trunk  which  soon  divided  again  into  the  radial  and 
ulnar  arteries  in  the  regular  way."  In  a  subject,  dissected  during 
the  past  winter  in  Sydenham  College,  this  variety  existed  in  both 
arms ;  and  I  have  seen  several  other  instances  of  a  similar  kind. 


BRACHIAL  ARTERY. 

The  Brachial  artery  passes  down  the  inner  side  of  the  arm,  from 
the  lower  border  of  the  latissimus  dorsi  to  the  bend  of  the  elbow, 
where  it  divides  into  the  radial  and  ulnar  arteries. 

Relations. — In  its  course  downwards,  it  rests  upon  the  coraco- 
brachialis  muscle,  internal  head  of  the  triceps,  brachialis  anticus, 
and  the  tendon  of  the  biceps.  To  its  inner  side  is  the  ulnar  nerve ; 
to  the  outer  side,  the  coraco-brachialis  and  biceps  muscles  ;  in  front 
it  has  the  basilic  vein,  and  is  crossed  by  the  median  nerve.  Its 
relations,  within  its  sheath,  are  the  vense  comites. 

Plan  of  the  relations  of  the  Brachial  Artery. 

In  Front. 
Basilic  vein, 
Deep  fascia, 


Median  nerve. 


Inner  Side. 
Ulnar  nerve. 


Brachial  Artery. 


Outer  Side. 
Coraco-brachialis, 
Biceps. 


Behind. 
Short  head  of  triceps 
Coraco-brachialis, 
Brachialis  anticus, 
Tendon  of  biceps. 


292  BRACHIAL  ARTERY BRANCHES. 

The  branches  of  the  brachial  artery  are,  the — 

Superior  profunda, 
Inferior  profunda, 
Anastomotica  magna, 
Muscular. 

The  Superior  profunda  arises  opposite  the  lower  border  of  the 
latissimus  dorsi,  and  winds  around  the  humerus,  between  the 
triceps  and  the  bone,  in  the  space  between  the  brachialis  anticus 
and  supinator  longus,  where  it  inosculates  with  the  radial  recurrent 
branch.  It  accompanies  the  musculo-spiral  nerve.  In  its  course 
it  gives  off  the  posterior  articular  artery,  which  descends  to  the 
elbow-joint,  and  a  more  superficial  branch  which  inosculates  with 
the  interosseous  articular  artery. 

The  Inferior  profunda  arises  from  about  the  middle  of  the  brachial 
artery,  and  descends  to  the  space  between  the  inner  condyle  and 
olecranon  in  company  with  the  ulnar  nerve,  where  it  inosculates 
with  the  posterior  ulnar  recurrent. 

The  Anastomotica  magna  is  given  off  nearly  at  right  angles  from 
the  brachial,  at  about  two  inches  above  the  joint.  It  passes  directly 
inwards,  and  divides  into  two  branches  which  inosculate  with  the 
anterior  and  posterior  ulnar  recurrent  arteries  and  with  the  inferior 
profunda. 

The  Muscular  branches  are  distributed  to  the  muscles  in  the  course 
of  the  artery,  viz.  to  the  coraco-brachialis,  biceps,  deltoid,  brachialis 
anticus  and  triceps. 

Varieties  of  the  Brachial  Artery, — The  most  frequent  peculiarity 
in  the  distribution  of  branches  from  this  artery  is  the  high  divi- 
sion of  the  radial,  which  arises  generally  from  about  the  upper 
third  of  the  brachial  artery  and  descends  to  its  normal  position 
at  the  bend  of  the  elbow.  The  ulnar  artery  sometimes  arises 
from  the  brachial  at  about  two  inches  above  the  elbow,  and  pursues 
either  a  superficial  or  deep  course  to  the  wrist ;  and  in  more  than 
one  instance  I  have  seen  the  interosseous  artery  arise  from  the  bra- 
chial a  little  above  the  bend  of  the  elbow.  The  two  profunda  arte- 
ries occasionally  arise  by  a  common  trunk,  or  there  may  be  two 
superior  profundse. 

RADIAL  ARTERY. 

The  Radial  artery,  one  of  the  divisions  of  the  brachial,  appears 
from  its  direction  to  be  the  continuation  of  that  trunk.  It  runs  along 
the  radial  side  of  the  fore-arm,  from  the  bend  of  the  elbow  to  the 
wrist ;  it  there  turns  round  the  base  of  the  thumb,  beneath  its 
extensor  tendons,  and  passes  between  the  two  heads  of  the  first 
dorsal  interosseous  muscle,  into  the  palm  of  the  hand.  It  then 
crosses  the  metacarpal  bones  to  the  ulnar  side  of  the  hand,  forming 
the  deep  palmar  arch,  and  terminates  by  inosculating  with  the  super- 
ficial palmar  arch. 


RADIAL  ARTERY. 


293 


In  the  upper  half  of  its  course,  the  radial  artery  is  situated  between 
the  supinator  longus  muscle,  by  which  it  is  overlapped  superiorly, 
and  the  pronator  radii  teres  ;  in  the  lower  half,  between  the  tendons 
of  the  supinator  longus  and  flexor  carpi  radialis.  It  rests  in  its 
course  downwards,  upon  the  supinator  brevis,  pronator  radii  teres, 
radial  origin  of  the  flexor  sublimis,  flexor  longus  pollicis,  and  pro- 
nator quadratus  ;  and  is  covered  in  by  the  integument  and  fasciae. 
At  the  wrist  it  is  situated  in  contact  with  the  dorsal  carpal  liga- 
ments and  beneath  the  extensor  tendons  of  the  thumb ;  and  in  the 
palm  of  the  hand,  beneath  the  flexor  tendons.  It  is  accompanied 
by  vensB  comites  throughout  its  course,  and  for  its  middle  third  is 
in  close  relation  with  the  radial  nerve. 


Plan  of  the  relations  of  the  Radial  Artery  in  the  fore-arm. 


In  Front. 
Deep  fascia, 
Supinator  long^us. 


Inner  Side, 
Pronator  radii  teres, 
Flexor  carpi  radialis. 


Radial  Artery. 


Outer  Side. 
Supinator  longus, 
Radial  nerve  (middle  third 
of  its  course). 


Behind, 
Supinator  brevis, 
Pronator  radii  teres, 
Flexor  sublimis  digitorum, 
Flexor  longus  pollicis, 
Pronator  quadratus, 
Wrist-joint. 

The  Branches  of  the  radial  artery  may  be  arranged  into  three 
groups,  corresponding  with  the  three  regions,  the  fore-arm,  the  wrist, 
and  the  hand ;  they  are — 

Recurrent  radial, 

Muscular. 

Superficialis  vote, 

Carpalis  anterior, 

Carpalis  posterior,  or  dorsalis  carpi, 

Metacarpalis, 

Dorsales  pollicis. 

Princeps,  or  magna  pollicis, 

Radialis  indicis, 

Interosseas, 

Perforantes. 


Fore-arm, 


Wrist, 


Hand, 


The  Recurrent  branch  is  given  ofl^  immediatly  below  the  elbow  ; 
it  ascends  in  the  space  between  the  supinator  longus  and  brachialis 
anticus  to  supply  the  joint,  and  inosculates  with  the  terminal  branches 
of  the  superior  profunda.  This  vessel  gives  off"  numerous  muscular 
branches. 

The  Muscular  branches  are  distributed  to  the  muscles  on  the  radial 
side  of  the  fore-arm. 

The  Superficialis  vola  is  given  off  from  the  radial  artery  while  at 


294 


RADIAL  ARTERY BRANCHES. 


Fig.  107.* 


the  wrist.  It  passes  between  the  fibres  of  the  abductor  pollicis 
muscle,  and  inosculates  with  the  termination  of  the  ulnar  artery, 
completing  the  superficial  palmar  arch.  This 
artery  is  very  variable  in  size,  being  some- 
times as  large  as  the  continuation  of  the 
radial,  and  at  other  times  a  mere  muscular 
ramusculus,  or  entirely  wanting ;  when  of 
large  size  it  supphes  the  palmar  side  of  the 
thumb  and  the  radial  side  of  the  index 
finger. 

The  Carp«Z  branches  are  intended  for  the 
supply  of  the  wrist,  the  anterior  carpal  in 
front,  and  the  posterior,  the  larger  of  the 
two,  behind.  The  carpqlis  posterior  crosses 
the  carpus  transversely  to  the  ulnar  border 
of  the  hand,  where  it  inosculates  with  the 
posterior  carpal  branch  of  the  ulnar  artery. 
Superiorly  it  sends  branches  which  inoscu- 
late with  the  termination  of  the  anterior 
interosseous  artery ;  inferiorly,  it  gives  off 
posterior  interosseous  branches,  which  anas- 
tomose with  the  perforating  branches  of  the 
deep  palmar  arch,  and  then  run  forwards 
upon  the  dorsal  interossei  muscles. 

The  Metacarpal  branch  runs  forwards 
on  the  second  dorsal  interosseous  muscle, 
and  inosculates  with  the  digital  branch  of 
the  superficial  palmar  arch,  which  supplies 
the  adjoining  sides  of  the  index  and  middle 
fingers.  Sometimes  it  is  of  large  size,  and 
the  true  continuation  of  the  radial  artery. 

The    Dorsales    'pollicis   are   two   small 

branches  which  run  along  the  sides  of  the 

dorsal  aspect  of  the  thumb. 

The  Princeps  pollicis  descends  along  the  border  of  the  metacarpal 

bone,  between  the  abductor  indicis  and  adductor  pollicis  to  the  base 

of  the  first  phalanx,  where  it  divides  into  two  branches,  which  are 

distributed  to  the  two  sides  of  the  palmar  aspect  of  the  thumb. 

*  The  arteries  of  the  fore-arm.  1.  The  lower  part  of  the  biceps  muscle.  2.  The 
inner  condyle  of  the  humerus  with  tlie  humeral  origin  of  the  pronator  radii  teres  and 
flexor  carpi  radialis  divided  across.  3.  The  deep  portion  of  the  pronator  radii  teres. 
4.  The  supinator  longus  muscle.  5.  The  flexor  longus  pollicis.  6.  The  pronator 
quadratiis.  7.  The  flexor  profundus  digitorum.  8.  The  flexor  carpi  ulnaris.  9.  The 
annular  ligament  with  the  tendons  passing  beneath  it  into  the  palm  of  the  hand  ;  the 
figure  is  placed  on  the  tendon  of  the  palmaris  longus  muscle,  divided  close  to  its  inser- 
tion. 10.  The  brachial  artery.  11.  The  anastomotiea  magna  inosculating  superiorly 
with  the  inferior  profunda,  and  inferiorly  with  the  anterior  ulnar  recurrent.  19.  The 
radial  artery.  13.  The  radial  recurrent  artery  inosculating  with  the  termination  of 
the  superior  profunda.  14.  The  superfieialis  vola;.  15.  The  ulnar  artery.  16.  Its 
superficial  palmar  arch  giving  off  digital  branches  to  three  fingers  and  a  half.  17. 
The  magna  pollicis  and  radialis  indicis  arteries.  18.  The  posterior  ulnar  recurrent. 
19.  The  anterior  interosseous  artery.  20.  The  posterior  interosseous,  as  it  is  passing 
through  the  interosseous  membrane. 


ULNAR  ARTERY,  295 

The  Radialis  indicis  is  also  situated  between  the  abductor  indicis 
and  adductor  poUicis,  and  runs  along  the  radial  side  of  the  index 
finger,  forming  its  collateral  artery.  This  vessel  is  frequently  a 
branch  of  the  princeps  pollicis. 

The  InterossecB,  three  or  four  in  number,  are  branches  of  fhe 
deep  palmar  arch ;  they  pass  forwards  upon  the  interossei  muscles 
and  inosculate  w^ith  the  digital  branches  of  the  superficial  arch, 
opposite  the  heads  of  the  metacarpal  bones. 

The  Perforantes,  three  in  number,  pass  directly  backwards  be- 
tween the  heads  of  the  dorsal  interossei  muscles,  and  inosculate  with 
the  posterior  interosseous  arteries. 

ULNAR  ARTERY. 

The  Ulnar  artery^,  the  other  division  of  the  brachial  artery,  crosses 
the  arm  obliquely  to  the  commencement  of  its  middle  third;  it  then 
runs  down  the  ulnar  side  of  the  fore-arm  to  the  wrist,  crosses  the 
annular  ligament,  and  forms  the  superficial  palmar  arch,  which 
terminates  by  inosculating  with  the  superficialis  volas. 

Relations. — In  the  upper  or  obhque  portion  of  its  course,  it  hes 
upon  the  brachialis  anticus,  and  flexor  profundus  digitorum ;  and  is 
covered  in  by  the  superficial  layer  of  muscles  of  the  fore-arm  and 
the  median  nerve.  In  the  second  part  of  its  course,  it  is  placed 
upon  the  flexor  profundus,  and  pronator  quadratus,  lying  between 
the  flexor  carpi  ulnaris  and  flexor  sublimis  digitorum.  While  cross- 
ing the  annular  hgament  it  is  protected  from  injury  by  a  strong  ten- 
dinous arch  thrown  over  it  from  the  pisiform  bone ;  and  in  the  palm 
it  rests  upon  the  tendons  of  the  flexor  sublimis,  being  covered  in  by 
the  palmaris  brevis  muscle  and  palmar  fascia.  It  is  accompanied 
in  its  course  by  the  venae  comites,  and  is  in  relation  with  the  ulnar 
nerve  for  the  lower  two-thirds  of  its  extent. 

Plan  of  the  relations  of  the  Ulnar  Artery : 

In  front. 
Deep  fascia, 

Superficial  layer  of  muscles, 
Median  nerve. 

In  the  Hand. 
Tendinous  arch  from  the  pisiform  bone, 
Palmaris  brevis  muscle, 
Palmar  fascia. 

Inner  side.  i  Outer  side. 

Flexor  carpi  ulnaris,  Ulnar  Arlerv  Flexor  sublimis  digilo- 

Ulnar  nerve  (lower  two-  '  '       |  rum. 


tliirds.) 


Behind. 
Brachialis  anticus. 
Flexor  profundus  digitorum. 
Pronator  quadratus. 

In  the  Hand. 
Annular  ligament. 
Tendons  of  the  flexor  sublimis  digitorum. 


296  fLNAR  ARTERY BRANCHES. 

The  Branches  of  the  idnar  artery jna.y  be  arranged  like  those  of 
the  radial  into  three  groups  : — 

Anterior  ulnar  recurrent, 

Posterior  ulnar  recurrent, 

Pny-e  n^m  J  T  ^  {  A  nterlor  interosseous, 

±oie-arm  <   Interosseous  -n    ^    •      •  . 


Muscular. 


Posterior  interosseous, 


T^  •  .         \    Carpalis  anterior, 

vvrist  .      ^    Carpalis  posterior,  or  dorsaUs  manus. 

Hand  .      Digitales. 

The  Anterior  ulnar  recurrent  arises  immediately  below  the  elbow, 
and  ascends  in  front  of  the  joint  between  the  pronator  radii  teres 
and  brachialis  anticus,  where  it  inosculates  with  anastomotica  magna 
and  inferior  profunda.  The  two  recurrent  arteries  frequently  arise 
by  a  common  trunk. 

The  Posterior  ulnar  recurrent,  larger  than  the  preceding,  arises 
immediately  below  the  elbow-joint,  and  passes  backwards  beneath 
the  origins  of  the  superficial  layer  of  muscles;  it  thena  scends  be- 
tween the  two  heads  of  the  flexor  carpi  ulnaris,  and  beneath  the 
ulnar  nerve,  and  inosculates  with  the  inferior  profunda  and  anasto- 
motica magna. 

The  Common  interosseous  artery  is  a  short  trunk  which  arises 
from  the  ulnar,  opposite  to  the  bicipital  tuberosity  of  the  radiu^.  It 
divides  into  two  branches,  the  anterior  and  posterior  interosseous 
arteries. 

The  Anterior  interosseous  passes  down  the  fore-arm  upon  the  inter- 
osseous membrane,  between  the  flexor  profundus  digitorum  and 
flexor  longus  pollicis,  and  behind  the  pronator  quadratus  it  pierces 
that  membrane  and  descends  to  the  back  of  the  wrist,  where  it  inos- 
culates with  the  posterior  carpal  branches  of  the  radial  and  ulnar. 
It  is  retained  in  connexion  with  the  interosseous  membrane  by 
means  of  a  thin  aponeurotic  arch. 

The  anterior  interosseous  artery  sends  a  branch  to  the  median 
nerve,  which  it  accompanies  into  the  hand.  The  median  artery  is 
sometimes  of  large  size,  and  I  have  seen  it  take  the  place  of  the 
superficial  palmar  arch. 

The  Posterior  interosseous  artery  passes  backwards  through  an 
openincr  between  the  upper  part  of  the  interosseous  membrane  and 
the  oblique  ligament,  and  is  distributed  to  the  muscles  on  the  poste- 
rior aspect  of  the  fore-arm.  It  gives  off  a  recurrent  branch,  which 
returns  upon  the  elbow  between  the  anconeus,  extensor  carpi  ulnaris 
and  supinator  brevis  muscles,  and  anastomoses  with  the  posterior 
terminal  branches  of  the  superior  profunda. 

The  Muscular  branches  supply  the  muscles  situated  along  the 
ulnar  border  of  the  fore-arm. 

The  Carpal  branches,  anterior  and  posterior,  are  distributed  to  the 


BRANCHES  OF  THE  THORACIC  AORTA.  297 

anterior  and  posterior  aspects  of  the  wrist-joint,  where  they  inoscu- 
late with  corresponding  branches  of  the  radial  artery. 

The  Digital  branches  are  given  off  from  the  superficial  palmar 
arch,  and  are  four  in  number.  The  first  and  smallest  is  distributed 
to  the  ulnar  side  of  the  little  finger.  The  other  three  are  short 
trunks,  which  divide  between  the  heads  of  the  metacarpal  bones, 
and  form  the  collateral  branch  of  the  radial  side  of  the  little  finger, 
the  collateral  branches  of  the  ring  and  middle  fingers,  and  the  col- 
lateral branch  of  the  ulnar  side  of  the  index  finger. 

The  Superficial  palmar  arch  receives  the  termination  of  the  deep 
palmar  arch  from  between  the  abductor  minimi  digiti  and  flexor 
brevis  minimi  digiti  near  to  their  origins,  and  terminates  by  inoscu- 
lating with  the  superficialis  volas  upon  the  ball  of  the  thumb.  The 
communication  between  the  superficial  and  deep  arch  is  generally 
described  as  the  communicating  branch  of  the  ulnar  artery. 

The  mode  of  distribution  of  the  arteries  to  the  hand  is  subject  to 
great  variety. 

BRANCHES  OF  THE  THORACIC  AORTA. 

Bronchial, 

(Esophageal, 

Intercostal. 

The  Bronchial  Arteries  are  four  in  number,  and  vary  both  in 
size  and  origin.  They  are  distributed  to  the  bronchial  glands  and 
tubes,  and  send  branches  to  the  oesophagus,  pericardium,  and  left 
auricle  of  the  heart.     These  are  the  nutritious  vessels  of  the  lungs. 

The  (Esophageal  Arteries  are  numerous  small  branches ;  they 
arise  from  the  anterior  part  of  the  aorta,  are  distributed  to  the  oeso- 
phagus, and  estabUsh  a  chain  of  anastamosis  along  that  tube  :  the 
superior  inosculate  with  the  bronchial  arteries,  and  with  oesophageal 
branches  of  the  inferior  thyroid  arteries ;  and  the  inferior  with 
similar  branches  of  the  phrenic  and  gastric  arteries. 

The  Intercostal,  or  posterior  intercostal  arteries,  arise  from  the 
posterior  part  of  the  aorta ;  they  are  nine  in  number  on  each  side, 
the  two  superior  spaces  being  supplied  by  the  superior  intercostal 
artery,  a  branch  of  the  subclavian.  The  right  intercostals  are  longer 
than  the  left,  on  account  of  the  position  of  the  aorta.  They  ascend 
somewhat  obliquely  from  their  origin,  and  cross  the  vertebral  column 
behind  the  thoracic  duct,  vena  azygos  major,  and  sympathetic  nerve, 
to  the  intercostal  spaces,  the  left  passing  beneath  the  superior  inter- 
costal vein,  the  vena  azygos  minor  and  sympathetic.  In  the  inter- 
costal spaces,  or  rather,  upon  the  external  intercostal  muscles,  each 
artery  gives  off  a  dorsal  branch,  which  passes  back  between  the 
transverse  processes  of  the  vertebrse,  lying  internally  to  the  middle 
costo-transverse  ligament,  and  divides  into  a  spinal  branch,  which 
supplies  the  spinal  cord  and  vertebrae,  and  a  muscular  branch  which 
is  distributed  to  the  muscles  and  integument  of  the  back.  It  then 
comes  into  relation  with  its  vein  and  nerve,  the  former  being  above, 
and  the  latter  below,  and  divides  into  two  branches  which  run  along 

38 


298  BRANCHES  OF  THE  ABDOMINAL  AORTA. 

the  borders  of  the  contiguous  ribs  between  the  two  planes  of  inter- 
costal muscles,  and  anastomose  with  the  anterior  intercostal  arteries, 
branches  of  the  internal  mammary.  The  branch  corresponding 
with  the  lower  border  of  each  rib  is  the  larger  of  the  two.  They 
are  protected  from  pressure  during  the  action  of  the  intercostal 
muscles,  by  little  tendinous  arches  thrown  across  and  attached  by 
each  extremity  to  the  bone. 

BRANCHES  OF  THE  ABDOMINAL  AORTA. 

Phrenic, 

C  Gastric, 
Coeliac  axis  <  Hepatic, 

(  Splenic, 
Superior  mesenteric, 
Spermatic, 
Inferior  mesenteric, 
Supra-renal,  or  capsular, 
Renal,  or  emulgent, 
Lumbar, 
Sacra  media. 

The  Phrenic  Arteries  are  given  off  from  the  anterior  part  of  the 
aorta  as  soon  as  that  trunk  has  passed  through  the  aortic  opening. 
Passing  obliquely  outwards  upon  the  under  surface  of  the  diaphragm, 
each  artery  divides  into  two  branches,  an  internal  hrancli  which 
runs  forwards  and  inosculates  with  its  fellow  of  the  opposite  side  in 
front  of  the  oesophageal  opening ;  and  an  external  branch  which 
proceeds  outwards  towards  the  great  circumference  of  the  muscle, 
and  sends  branches  to  the  supra-renal  capsules.  The  phrenic  arte- 
ries inosculate  with  branches  of  the  internal  mammary,  inferior 
intercostal,  epigastric,  oesophageal,  gastric,  hepatic,  and  supra-renal 
arteries.  They  are  frequently  derived  from  the  coeliac  axis,  or 
from  one  of  its  divisions,  and  sometimes  they  give  off  the  supra- 
renal arteries. 

The  CcELiAc  Axis  {y-oikla  ventriculus)  is  the  first  single  trunk  given 
off  from  the  abdominal  aorta.  It  arises  opposite  the  upper  border 
of  the  first  lumbar  vertebrae,  is  about  half  an  inch  in  length,  and 
divides  into  three  large  branches — gastric,  hepatic,  and  splenic. 

Relations. — The  trunk  of  the  coeliac  axis  has  in  relation  with  it, 
in  front  the  lesser  omentum  ;  on  the  right  side  the  right  semilunar 
ganghon  and  lobulus  Spigelii  of  the  liver ;  on  the  left  side  the  left 
semilunar  ganglion  and  cardiac  portion  of  the  stomach ;  and  below 
the  upper  border  of  the  pancreas  and  lesser  curve  of  the  stomach. 
It  is  completely  surrounded  by  the  solar  plexus. 

The  Gastric  Artery  (coronaria  vcntriculi),  the  smallest  of  the 
three  branches  of  the  coeliac  axis,  ascends  between  the  two  layers 
of  the  lesser  omentum  to  the  cardiac  orifice  of  the  stomach,  then 
runs  along  the  lesser  curvature  to  the  pylorus,  and  inosculates  with 
the  pyloric  brancii  of  the  hepatic.     It  is  distributed  to  tiie  lower 


ABDOMINAL  AORTA. 


299 


extremity  of  the  oesophagus  and  lesser  curve  of  the  stomach,  and 
anastomoses  with  the  oesophageal  arteries  and  vasa  brevia  of  the 
splenic  artery. 


Fiff.  108.* 


The  Hepatic  Artery  curves  forwards,  and  ascends  along  the  right 
border  of  the  lesser  omentum  to  the  liver,  where  it  divides  into  two 
branches  (right  and  left),  which  enter  the  transverse  fissure,  and  are 
distributed  along  the  portal  canals  to  the  right  and  left  lobcs.f  It  is 
in  relation  in  the  right  border  of  the  lesser  omentum,  with  the  ductus 
communis  choledochus  and  portal  vein,  and  is  surrounded  by  the 

*  The  abdominal  aorta  with  its  branches.  1.  The  phrenic  arteries.  2.  The  coeliac 
axis.  3.  The  gastric  artery.  4.  The  hepatic  artery,  dividing  into  the  right  and  left 
hepatic  branches.  5.  The  splenic  artery,  passing  outwards  to  the  spleen.  6.  The 
supra-renal  artery  of  the  right  side.  7.  Tiie  right  renal  artery,  which  is  longer  than 
the  left,  passing  outwards  to  the  right  kidney.  8.  Tlic  lumbar  arteries.  9.  Thc'superior 
mesenteric  artery.  10.  The  two  spermatic  arteries.  11.  The  inferior  mesenteric 
artery.  12.  The  sacra  media.  13.  The  common  iliacs.  14.  The  internal  ihao  of  the 
right  side.  15.  The  external  iliac  artery.  16.  The  epigastric  artery.  17.  The  cir- 
cumflexa  ilii  artery.     18.  The  femoral  artery. 

t  For  the  mode  of  distribution  of  the  hepatic  artery  within  the  liver,  see  the  "  Minute 
Anatomy"  of  that  organ  in  tlie  Chajjtcr  on  the  Viscera. 


300  SPLENIC  ARTERY BRANCHES. 

hepatic  plexus  of  nerves  and  numerous  lymphatics.  There  are  some- 
times two  iiepatic  arteries,  in  which  case  one  is  derived  from  the 
superior  mesenteric  artery. 

The  Branches  of  the  hepatic  artery  are  the 

Pyloric, 

^     ,      J     J       ,.       (  Gastro-epiploica  dextra, 
Gastro-duodenahs,    <  -d  5      j      ]       r 

{  rancreatico-duodenahs. 

Cystic. 

The  Pyloric  branch  given  off  from  the  hepatic  near  to  the  pylorus, 
is  distributed  to  the  commencement  of  the  duodenum  and  to  the 
lesser  curve  of  the  stomach,  where  it  inosculates  with  the  gastric 
artery. 

The  Gastro-duodenaUs  artery  is  a  short  but  large  trunk,  which 
descends  behind  the  pylorus,  and  divides  into  two  branches,  the 
gastro-epiploica  dextra,  and  pancreatico-duodenalis.  Previously  to 
its  division,  it  gives  off  some  inferior  pyloric  branches  to  the  small 
end  of  the  stomach. 

The  Gastro-epiploica  dextra  runs  along  the  great  curve  of  the 
stomach  lying  between  the  two  layers  of  the  great  omentum,  and 
inosculates  at  about  its  middle  with  the  gastro-epiploica  sinistra,  a 
branch  of  the  splenic  artery.  It  supplies  the  great  curve  of  the 
stomach  and  the  great  omentum ;  hence  the  derivation  of  its  name. 

The  Pancreatico-duodenalis  curves  along  the  fixed  border  of  the 
duodenum,  partly  concealed  by  the  attachment  of  the  pancreas,  and 
is  distributed  to  the  pancreas  and  duodenum.  It  inosculates  infe- 
riorly  with  the  first  jejunal  and  with  the  pancreatic  branches  of  the 
superior  mesenteric  artery. 

The  Cystic  artery,  generally  a  branch  of  the  right  hepatic,  is  of 
small  size,  and  ramifies  between  the  coats  of  the  gall  bladder,  pre- 
viously to  its  distribution  to  the  mucous  membrane. 

The  Splenic  Artery,  the  largest  of  the  three  branches  of  the 
coeliac  axis,  passes  horizontally  to  the  left  along  the  upper  border  of 
the  pancreas,  and  divides  into  five  or  six  large  branches  which  enter 
the  hilum  of  the  spleen  and  are  distributed  to  its  structure.  In  its 
course  it  is  tortuous  and  serpentine,  and  frequently  makes  a  com- 
plete turn  upon  itself  It  lies  in  a  narrow  groove  in  the  upper  border 
of  the  pancreas,  and  is  accompanied  by  the  splenic  vein,  and  by  the 
splenic  plexus  of  nerves. 

The  Branches  of  the  splenic  artery  are — 

Pancreaticffi  parvce, 
Pancreatica  magna, 
Vasa  brevia, 
Gastro-epiploica  sinistra. 

The  Pancrenticai  parvce  arc  numerous  small  branches  distributed 
to  the  pancreas,  as  the  splenic  artery  runs  along  its  upper  border. 


SUPERIOR  MESEPTTERIC  ARTERY. 


301 


One  of  these,  larger  than  the  rest,  follows  the  course  of  the  pancre- 
atic duct,  and  is  called  pancreatica  magna. 

The  Fasa  hrevia  are  five  or  six  branches  of  small  size  which  pass 
from  the  extremity  of  the  splenic  artery  and  its  terminal  branches, 
between  the  layers  of  the  gastro-splenic  omentum,  to  the  great  end 
of  the  stomach,  to  which  they  are  distributed,  inosculating  wdth 
branches  of  the  gastric  artery  and  of  the  gastro-epiploica  sinistra. 

The  Gastro-epiploica  sinistra  appears  to  be  the  continuation  of 
the  splenic  artery ;  it  passes  forwards  from  left  to  right,  along  the 
great  curve  of  the  stomach,  lying  between  the  layers  of  the  great 
omentum,  and  inosculates  with  the  gastro-epiploica  dextra.  It  is 
distributed  to  the  greater  curve  of  the  stomach  and  to  the  great 


omentum. 


Fig.  109.* 


The  Superior  Mesenteric  Artery,  the  second  of  the  single 
trunks,  and  next  in  size  to  the  coeUac  axis,  arises  from  the  aorta  im- 


*  The  distribution  of  the  branches  of  the  coeliac  axis.  1.  The  liver.  2.  Its  trans- 
verse fissure.  3.  The  gall  bladder.  4.  The  stomach.  5.  The  entrance  of  the  oeso- 
phagus. 6.  The  pylorus.  7.  The  duodenum,  its  descending  portion.  8.  The  trans- 
verse portion  of  the  duodenum.  9.  The  pancreas.  10.  The  spleen.  11.  The  aorta. 
12.  The  coehac  axis.  13.  The  gastric  artery.  14.  The  hepatic  artery.  15.  Its  pyloric 
branch.  16.  The  gastro-duodenalis.  17.  The  gastro-epiploica  dextra.  18.  The 
pancreatico-duodenalis,  inosculating  with  a  brancli  from  the  superior  mesenteric  artery. 
19.  The  division  of  the  liepatic  artery  into  its  right  and  left  branches;  the  right  giving 
off  the  cystic  branch.  20.  The  splenic  artery,  traced  by  dotted  lines  behind  the  stomach 
to  the  spleen.  21.  The  gastro-epiploica  sinistra,  inosculating  along  the  great  curva- 
ture of  the  stomach  with  the  gastro-epiploica.  dextra.  22.  The  pancreatica  magna. 
23.  The  vasa  brevia  to  the  great  end  of  the  stomach,  inosculating  with  branches  of  the 
gastric  artery.  24.  The  superior  mesenteric  artery,  emerging  from  between  the  pan- 
creas and  the  transverse  portion  of  the  duodenum. 


302 


SUPERIOR  3IESENTERIC  ARTERY. 


mediately  below  that  vessel,  and  behind  the  pancreas.  It  passes  for- 
wards betv/een  the  pancreas  and  transverse  duodenum,  and  descends 
within  the  layers  of  the  mesentery,  to  the  right  iliac  fossa,  where  it 
terminates  very  much  diminished  in  size.  It  forms  a  curve  in  its 
course,  the  convexity  being  directed  towards  the  left,  and  the  con- 
cavity to  the  right.  It  is  in  relation  near  its  commencement  with 
the  portal  vein ;  and  is  accompanied  by  two  veins,  and  the  superior 
mesenteric  plexus  of  nerves. 

The  brandies  of  the  superior  Mesenteric  Artery  are — 

Vasa  intestini  tenuis, 
Ileo-colica, 
Colica  dextra, 
Colica  media. 

Fig.  110* 


*  The  course  and  distribution  of  the  superior  mesenteric  artery.  J.  The  descending 
portion  of  the  duodenum.  2.  The  transverse  portion.  3.  TJic  pancreas.  4.  The 
jejunum.  5.  The  ileum.  6.  The  ccecum  from  which  the  ap[)endix  vermiformis  is 
seen  projecting.  7.  The  ascending  colon.  8.  Tiic  transverse  colon.  9.  The  com- 
mencement of  ^the  descending  colon.  10.  The  superior  mesenteric  artery.  11.  The 
colica  media.  12.  The  branch  vi^hich  inosculates  with  the  colica  sinistra.  13.  The 
branch  of  the  superior  mesenteric  artery,  whicii  inoscidates  with  the  pancreatico- 
duodenalis.  14.  The  colica  dextra.  15.  The  ileo-coliea.  IG,  IG.  Tiic  branches  from 
the  convexity  of  the  superior  mesenteric  t»thc  small  intestines. 


SPERMATIC  ARTERIES.  303 

The  Vasa  intestini  tenuis  arise  from  the  convexity  of  the  superior 
mesenteric  artery.  They  vary  from  fifteen  to  twenty  in  number, 
and  are  distributed  to  the  small  intestine  from  the  duodenum  to  the 
termination  of  the  ileum.  In  their  course  between  the  layers  of  the 
mesentery,  they  form  a  series  of  arches  by  the  inosculation  of  their 
larger  branches;  from  these  are  developed  secondary  arches,  and 
from  the  latter  a  third  series  of  arches,  from  which  the  branches 
arise  which  are  distributed  to  the  coats  of  the  intestine.  From  the 
middle  branches  a  fourth  and  sometimes  even  a  fifth  series  of  arches 
is  produced.  By  means  of  these  arches  a  direct  communication  is 
established  between  all  the  branches  given  off  from  the  convexity  of 
the  superior  mesenteric  artery ;  the  superior  branches  moreover  sup- 
ply the  pancreas  and  duodenum,  and  inosculate  with  the  pancreatico- 
duodenalis ;  and  the  inferior  with  the  ileo-colica. 

The  Ileo-colic  arterij  is  the  last  branch  given  off  from  the  conca- 
vity of  the  superior  mesenteric.  It  descends  to  the  right  iliac  fossa, 
and  divides  into  branches  which  communicate  and  form  arches,  from 
which  branches  are  distributed  to  the  termination  of  the  ileum,  the 
cEecum,  and  the  commencement  of  the  colon.  This  artery  inoscu- 
lates on  the  one  hand  with  the  last  branches  of  the  vasa  intestini 
tenuis,  and  on  the  other  with  the  colica  dextra. 

The  Colica  dextra  arises  from  about  the  middle  of  the  concavity 
of  the  superior  mesenteric,  and  divides  into  branches  which  form 
arches,  and  are  distributed  to  the  ascending  colon.  Its  descending 
branches  inosculate  with  the  ileo-colica,  and  the  ascending  with  the 
colica  media. 

The  Colica  media  arises  from  the  upper  part  of  the  concavity  of 
the  superior  mesenteric,  and  passes  forwards  between  the  layers  of 
the  transverse  mesocolon,  where  it  forms  arches,  and  is  distributed 
to  the  transverse  colon.  It  inosculates  on  the  right  with  the  colica 
dextra ;  and  on  the  left  with  the  colica  sinistra,  a  branch  of  the  infe- 
rior mesenteric  artery. 

The  Spermatic  Arteries  are  two  small  vessels  which  arise  from 
the  front  of  the  aorta  below  the  superior  mesenteric ;  from  this  origin 
each  artery  passes  obliquely  outwards,  and  accompanies  the  corre- 
sponding ureter  along  the  front  of  the  psoas  muscle  to  the  border  of 
the  pelvis,  where  it  is  in  relation  with  the  external  iliac  artery.  It 
is  then  directed  outwards  to  the  internal  abdominal  ring,  and  follows 
the  course  of  the  spermatic  cord  along  the  spermatic  canal,  and 
through  the  scrotum  to  the  testicle,  to  which  it  is  distributed.  The 
right  spermatic  artery  lies  in  front  of  the  vena  cava,  and  both  ves- 
sels are  accompanied  by  their  corresponding  veins  and  by  the  sper- 
matic plexuses  of  nerves. 

The  spermatic  arteries  in  the  female  descend  into  the  pelvis  and 
pass  between  the  two  layers  of  the  broad  ligaments  of  the  uterus,  to 
be  distributed  to  the  ovaries,  Fallopian  tubes,  and  round  ligaments; 
along  the  latter  they  are  continued  to  the  inguinal  canal  and  labium 
at  each  sid?. 

They  inosculate  with  the  uterine  arteries. 


304 


lA^FERIOR  MESENTERIC  ARTERY. 


The  Inferior  Mesenteric  Artery,  smaller  than  the  superior, 
arises  from  the  abdominal  aorta,  about  two  inches  below  the  origin 
of-  that  vessel,  and  descends  between  the  layers  of  the  left  mesocolon, 
to  the  left  iliac  fossa,  where  it  divides  into  three  branches: 

Colica  sinistra,  superior, 

Sigmoidese,  or  colica  sinistra  media  and  inferior. 

Superior  ha;morrhoidal. 

The  Colica  sinistra  is  distributed  to  the  descending  colon,  and 
ascends  to  inosculate  with  the  colica  media.  This  is  the  largest 
arterial  inosculation  in  the  body. 

Fig.  11]  * 


*  The  distribution  and  brandies  of  the  inferior  mesenteric  artery.  1,  ].  The  supe- 
rior artery  with  its  brandies  and  the  small  intestines  turned  over  to  the  right  side.  2. 
The  cxcum  and  ap])endix  ca;ci.  3.  The  ascending-  colon.  4.  The  transverse  colon 
raised  upwards.  r>.  Tlie  descending  colon.  G.  Its  sigmoid  flexure.  7.  The  rectum. 
8.  The  aorta.  9.  Tiie  inferior  mesenteric  artery.  10.  The  eoliea  sinistra,  inosculating 
with  11.  The  colica  media,  a  branch  of  the  superior  mesenteric  artery.  12,  12.  Sig- 
moid branches.  13.  The  fiuiierior  ha-morrhoidal  artcu'y.  14.  The  pancreas.  15,  The 
descending  portion  of  the  duodentmi. 


RENAL  ARTERIES- — LUMBAR  ARTERIES.  305 

The  Sigmoidece  are  several  large  branches  which  are  distributed 
to  the  sigmoid  flexure  of  the  descending  colon.  They  form  arches, 
and  inosculate  above  with  the  colica  sinistra,  and  below  with  the 
superior  hsemorrhoidal  artery. 

The  Superior  hcEmorrhoidal  artery  is  the  continuation  of  the 
inferior  mesenteric.  It  crosses  the  ureter  and  common  iliac  artery 
of  the  left  side,  and  descends  between  the  two  layers  of  the  meso- 
rectum  as  far  as  the  middle  of  the  rectum  to  which  it  is  distributed, 
anastomosing  with  the  middle  and  external  hsemorrhoidal  arteries. 

The  Supra-Rexal  are  two  small  vessels  which  arise  from  the 
aorta  immediately  above  the  renal  arteries,  and  are  distributed  to 
the  supra-renal  capsules.  They  are  sometimes  branches  of  the 
phrenic  or  of  the  renal  arteries. 

The  Reival  Arteries  (emulgent)  are  two  large  trunks  given  off 
from  the  sides  of  the  aorta  immediately  below  the  superior  mesen- 
teric artery ;  the  right  is  longer  than  the  left  on  account  of  the  posi- 
tion of  the  aorta,  and  passes  behind  the  vena  cava  to  the  kidney  of 
that  side.  The  left  is  somewhat  higher  than  the  right.  They  divide 
into  several  large  branches  previously  to  entering  the  kidney,  and 
ramify  very  minutely  in  its  vascular  portion.  The  renal  arteries 
supply  several  small  branches  to  the  supra-renal  capsules. 

The  Lumbar  Arteries  correspond  with  the  intercostals  in  the 
chest ;  they  are  four  or  five  in  number  on  each  side,  and  curve 
around  the  bodies  of  the  lumbar  vertebras  beneath  the  psoas  muscles, 
and  divide  into  two  branches ;  one  of  which  passes  backwards 
between  the  transverse  processes  and  is  distributed  to  the  vertebra3 
and  spinal  cord  and  to  the  muscles  of  the  back,  whilst  the  other 
takes  its  course  behind  the  quadratus  lumborum  muscle  and  supplies 
the  abdominal  muscles.  The  first  lumbar  artery  runs  along  the 
lower  border  of  the  last  rib,  and  the  last  along  the  crest  of  the  ilium. 
In  passing  between  the  psoas  muscles  and  the  vertebra?,  they  are 
protected  by  a  series  of  tendinous  arches,  which  defend  them  and 
the  communicating  branches  of  the  sympathetic  nerve  from  pressure 
during  the  action  of  the  muscle. 

The  Sacra  Media  arises  from  the  posterior  part  of  the  aorta  at 
its  bifurcation,  and  descends  along  the  middle  of  the  anterior  surface 
of  the  sacrum  to  the  first  piece  of  the  coccyx  where  it  terminates 
by  inosculating  with  the  lateral  sacral  arteries.  It  distributes  branches 
to  the  rectum  and  anterior  sacral  nerves,  and  inosculates  on  either 
side  with  the  lateral  sacral  arteries. 

Varieties  in  the  Brandies  of  the  abdominal  Aorta. — The  phrenic 
arteries  are  very  rarely  both  derived  from  the  aorta.  One  or  both 
may  be  branches  of  the  cceliac  axis ;  one  may  proceed  from  the 
gastric  artery,  from  the  renal,  or  from  the  upper  lumbar  artery. 
There  are  occasionally  three  or  more  phrenic  arteries.  The  coeliac 
axis  is  very  variable  in  length,  and  gives  otT  its  branches  irregularly. 
There  are  sometimes  two  or  even  three  hepatic  arteries,  one  of 
which  may  be  derived  from  the  gastric  or  even  from  the  superior 
mesenteric.    The  colica  media  is  sometimes  derived  from  the  hepatic 

39 


306  COMMON  ILIAC  ARTERIES. 

arteiy.  The  spermatic  arteries  are  very  variable  both  in  origin  and 
number.  The  right  spermatic  may  be  a  branch  of  the  renal  artery, 
and  the  left  a  branch  of  the  inferior  mesenteric.  The  supra-renal 
arteries  may  be  derived  from  the  phrenic  or  renal  arteries.  The 
renal  arteries  present  several  varieties  in  number ;  there  may  be 
three  or  even  four  arteries  on  one  side  and  one  only  on  the  other. 
When  there  are  several  renal  arteries  on  one  side,  one  may  arise 
from  the  common  iliac  artery,  from  the  front  of  the  aorta  near  its 
lower  part,  or  from  the  internal  iliac. 

COMMOIV  ILIAC  ARTERIES. 

The  abdominal  aorta  divides  opposite  the  fourth  lumbar  vertebras 
into  the  two  common  iliac  arteries.  Sometimes  the  bifurcation  takes 
place  as  high  as  the  third,  and  occasionally  as  low  as  the  fifth  lum- 
bar vertebra.  The  common  iliac  arteries  are  about  two  inches  and 
a  half  in  lengtli ;  they  diverge  from  the  termination  of  the  aorta,  and 
pass  downwards  and  outwards  on  each  side  to  the  margin  of  the 
pelvis  opposite  the  sacro-iliac  symphysis,  where  they  divide  into  the 
internal  and  external  iliac  arteries.  In  old  persons  the  common  iliac 
arteries  are  more  or  less  dilated  and  curved  in  their  course. 

The  Right  common  iliac  is  somewhat  longer  than  the  left  and 
forms  a  more  obtuse  angle  with  the  termination  of  the  aorta ;  the 
angle  of  bifurcation  is  greater  in  the  female  than  in  the  male. 

Relations. — The  relations  of  the  two  arteries  are  different  on  the 
two  sides  of  the  body.  The  right  common  iliac  is  in  relation  in 
front  with  the  peritoneum,  and  is  crossed  at  its  bifurcation  by  the 
ureter.  It  is  in  relation  posteriorly  with  the  two  common  iliac  veins, 
and  externally  with  the  psoas  magnus.  The  left  is  in  relation  in 
front  with  the  peritoneum,  and  is  crossed  by  the  rectum  and  superior 
ha;morrhoidal  artery,  and  at  its  bifurcation  by  the  ureter.  It  is  in 
relation  behind  with  the  left  common  iliac  vein,  and  externally  with 
the  psoas  magnus. 

INTERNAL  ILIAC  ARTERY. 

The  Internal  Iliac  Artery  is  a  short  trunk,  varying  in  length  from 
an  inch  to  two  inches.  It  descends  obliquely  to  a  point  opposite  the 
upper  margin  of  the  great  sacro-ischiatic  foramen,  where  it  divides 
into  an  anterior  and  a  posterior  trunk. 

Relations. — This  artery  rests  externally  upon  the  sacral  plexus 
and  upon  the  origin  of  the  pyriformis  muscle ;  posteriorly  it  is  in 
relation  with  the  internal  iliac  vein,  and  anteriorly  with  the  ureter. 

Branches. — The  branches  of  the  anterior  trunk  are  the — 

Umbilical,  Ischiatic, 

Middle  vesical.  Internal  pudic. 

Middle  ha^morrhoidal. 

And  in  the  female  the — 
Uterine,  Vaginal. 


INTERNAL  ILIAC  ARTERY. 


307 


And  of  the  posterior  trunk  the — 

Iho-lumbar,  Lateral  sacral, 

Obturator,  Gluteal. 

The  umbilical  artery  is  the  commencement  of  the  fibrous  cord 
into  which  the  umbilical  artery  of  the  foetus  is  converted  after  birth. 
In  after  life,  the  cord  remains  pervious  for  a  short  distance  and  con- 
stitutes the  umbilical  artery  of  the  adult,  from  which  the  superior 
vesical  artery  is  given  off  to  the  fundus  and  anterior  aspect  of  the 
bladder.  The  cord  may  be  traced  forwards  by  the  side  of  the 
fundus  of  the  bladder  to  near  its  apex,  whence  it  ascends  by  the 
side  of  the  linea  alba  and  urachus  to  the  umbilicus. 

Fig.  112.* 


The  Middle  vesical  artery  is  generally  a  branch  of  the  umbilical, 
and  sometimes  of  the  internal  iliac.  It  is  somewhat  larger  than  the 
superior  vesical,  and  is  distributed  to  the  posterior  part  of  the  body 
of  the  bladder,  the  vesiculse  seminales,  and  prostate  gland. 

The  Middle  ha^morrhoidal  artery  is  as  frequently  derived  from  the 
ischiatic  or  internal  pudic  as  from  the  internal  iliac.  It  is  of  variable 
size,  and  is  distributed  to  the  rectum,  base  of  the  bladder,  vesiculse 
seminales,  and  prostate  gland ;  and  inosculates  with  the  superior  and 
external  hasmorrhoidal  arteries. 


*  Tlie  distribution  and  branches  of  the  iliac  arteries.  1.  Tlic  aorta.  2.  The  left 
common  iliac  artery.  3.  The  external  iliac.  4.  The  epigastric  artery.  5.  The  cir- 
cumflcxa  ilii.  6.  The  internal  iliac  artery.  7.  Its  anterior  trunk.  8.  Its  posterior 
trunk.  !).  The  umbilical  artery  giving  olF  (10)  the  superior  vesical  artery.  After  the 
origin  of  this  branch,  the  umbilical  artery  becomes  converted  into  a  fibrous  cord — the 
umbilical  ligament.  11.  The  internal  pudic  artery  passing  behind  the  spine  of  the 
ischium  (12)  and  lesser  sacro-ischiatic  ligament.  13.  Tlic  middle  hajmorrlioidal  artery. 
14.  The  ischiatic  artery,  also  passing  behind  the  anterior  sacro-ischiatic  ligament  to 
escape  from  tlie  pelvis.  15.  Its  inferior  vesical  branch.  16.  Tlie  ilio-lumbar,  the  fust 
brancli  of  the  posterior  trunk  (8)  ascending  to  inosculate  with  tlie  circumflcxa  ilii  arlery 
(5)  and  form  an  arcli  along  the  crest  of  the  ilium.  17.  The  obturator  artery.  18.  The 
lateral  sacral.  19.  The  gluteal  artery  escaping  from  tlic  pelvis  through  the  upper  part 
of  the  great  sacro-ischiatic  foramen.  20.  The  sacra  media.  21.  The  right  common 
iliac  artery  cut  short.     22.  The  femoral  artery. 


308 


ISCHIATIC  ARTERY, 


The  IscHiATic  Artery  is  the  larger  of  the  two  terminal  branches 
of  the  anterior  division  of  the  internal  iliac.  It  passes  dowmvards 
between  the  posterior  border  of  the  levator  ani,  and  the  pyriformis, 
resting  upon  the  sacral  plexus  of  nerves  and  lying  behind  the  internal 
pudic  artery,  to  the  lower  border  of  the  great  ischiatic  notch,  where 
it  escapes  from  the  pelvis  below  the  pyriformis  muscle.  It  then 
descends  in  the  space  between  thetrochanter  major  and  the  tube- 
rosity of  the  ischium  in  company  with  the  ischiatic  nerves,  and 
divides  into  branches. 

Fig.  113* 


Its  branches  within  the  pelvis  are  the  inferior  hmmorrlioidal  which 
supplies  the  rectum  conjointly  with  the  middle  hsemorrhoidal  and 
sometimes  takes  the  place  of  that  artery,  and  the  inferior  vesical 
which  is  distributed  to  the  base  and  neck  of  the  bladder,  the  vesiculse 
seminales,  and  prostate  gland.  The  branches  external  to  the  pelvis, 
are  four  in  number — coccygeal,  inferior  gluteal,  comes  nervi  ischia- 
tici,  and  muscular  branches. 

The  Coccygeal  branch  pierces  the  great  sacro-ischiatic  ligament, 
and  is  distributed  to  the  coccygcus  and  levator  ani  muscles,  and  to 
the  integument  around  the  anus  and  coccyx. 

*  The  arteries  of  the  perineum ;  on  the  rijrlit  side  the  superficial  arteries  are  seen, 
and  on  the  left  the  deep.  1.  The  penis,  consisting'  of  corpus  spongiosum  and  corpus 
cavernosum.  The  /;rus  penis  on  the  Icfl  side  is  cut  througli.  2.  The  accclcratores 
urinoB  muscles,  enclosing  the  bulbous  portion  of  the  cori)us  spongiosum.  3.  The  erector 
penis,  spread  out  upon  the  crus  penis  of  the  right  side.  4.  TJic  anus,  surrounded  by 
the  sphincter  ani  muscle.  .5.  The  ramus  of  the  ischium  and  os  pubis.  G.  The  tube- 
rosity of  the  ischium.  7.  The  lesser  sacro-ischiatic  ligament,  attached  by  its  small 
extremity  to  the  si)iue  of  the  ischium.  8.  The  coccyx,  y.  Tlio  internal  jjudic  artery, 
crossing  tiic  spine  of  tlie  ischium,  and  entering  tiic  perineum.  10.  Inferior  liremor- 
rhoidal  branch.  11.  The  supcrticialis  perinci  artery,  giving  oil'  a  small  branch, 
transversalis  perinci,  upon  the  transvcrsus  perinci  muscle.  12.  The  same  artery  on 
the  left  side  cut.  off.  13.  The  artery  of  the  l>ulb.  14.  TJie  two  terminal  branches  of 
the  internal  pudic  artery;  one  is  seen  entering  tlio  divided  extremity  of  the  crus  penis, 
the  artery  of  the  corpus  cavernosum ;  the  oilier,  the  dorsalis  penis,  ascends  upon  the 
dorsum  of  the  organ. 


INTERNAL  PUDIC  ARTERY.  309 

The  Inferior  gluteal  branches  supply  the  gkiteus  maximus  muscle. 

The  Comes  nervi  iscliiatici  is  a  small  but  regular  branch,  which 
accompanies  the  great  ischiatic  nerve  to  the  lower  part  of  the  thigh. 

The  Muscular  branches  supply  the  muscles  of  the  posterior  part 
of  the  hip  and  thigh,  and  inosculate  with  the  internal  and  external 
circumflex  arteries,  with  the  obturator,  and  with  the  superior  per- 
forating artery. 

The  Internal  Pudic  Artery,  the  other  terminal  branch  of  the 
anterior  trunk  of  the  internal  iliac,  descends  in  front  of  the  ischiatic 
artery  to  the  lower  border  of  the  great  ischiatic  foramen.  It  emerges 
from  the  pelvis  through  the  great  sacro-ischiatic  foramen  below  the 
pyriformis  muscle,  crosses  the  spine  of  the  ischium,  and  re-enters 
the  pelvis  through  the  lesser  sacro-ischiatic  foramen ;  it  then  crosses 
the  internal  obturator  muscle  to  the  ramus  of  the  iscliium,  being 
situated  at  about  an  inch  from  the  margin  of  the  tuberosity,  and 
bound  down  by  the  obturator  fascia ;  it  next  ascends  the  ramus  of 
the  ischium,  enters  between  the  two  layers  of  the  deep  perineal 
fascia  lying  along  the  border  of  the  ramus  of  the  os  pubis,  and  at 
the  symphysis,  pierces  the  anterior  layer  of  the  deep  perineal  fascia, 
and  very  much  diminished  in  size  reaches  the  dorsum  of  the  penis 
along  which  it  runs,  supplying  that  organ  under  the  name  of  the 
dorsalis  penis. 

Branches. — The  branches  of  the  internal  pudic  artery  within  the 
pelvis  are  several  small  ramuscules  to  the  base  of  the  bladder,  the 
vesicute  seminales,  and  the  prostate  gland;  and  the  hcBmorrlioidal 
branch  which  supplies  the  middle  of  the  rectum,  and  frequently  takes 
the  place  of  the  middle  hcemorrhoidal  branch  of  the  internal  ihac. 
The  branches,  external  to  the  pelvis,  are  the 

Inferior  htemorrhoidal, 
Superficialis  perinei, 

Transversahs  perinei, 
Arteria  bulbosa, 
Arteria  corporis  cavernosi, 
Arteria  dorsalis  penis. 

The  Inferior  hcBmorrhoidal  artery  is  given  off  by  the  internal  pudic 
while  behind  the  tuberosity  of  the  ischium.  It  is  distributed  to  the 
anus,  and  to  the  muscles,  the  fascia,  and  the  integument  in  the  anal 
region  of  the  perineum. 

The  Superficial  perineal  arterij  is  given  off  near  the  attachment 
of  the  crus  penis;  it  pierces  the  connecting  layer  of  the  superficial 
and  deep  perineal  fascia,  and  runs  forwards  across  the  transversus 
perinei  muscle,  and  along  the  groove  between  the  accelerator  uringe 
and  erector  penis  to  the  septum  scroti,  upon  which  it  ramifies  under 
the  name  of  arteria  septi.  It  distributes  branches  to  the  scrotum, 
and  to  the  perineum  in  its  course  fonvards.  One  of  the  latter,  larger 
than  the  rest,  crosses  the  perineum,  resting  on  the  transversus  peri- 
nei muscle,  and  is  named  the  transversalis  perinei. 


310  UTERINE,  VAGINAL,  AND  OBTTIRATOE  ARTERIES. 

The  Artery  of  the  hulh  is  given  off  from  the  pudic  nearly  opposite 
the  opening  for  the  transmission  of  the  urethra;  it  passes  nearly 
transversely  inwards  between  the  two  layers  of  the  deep  perineal 
fascia,  and  pierces  the  anterior  layer  to  enter  the  corpus  spongiosum 
at  its  bulbous  extremity.     It  is  distributed  to  the  corpus  spongiosum. 

The  Artery  of  ike  corpus  cavernosum  pierces  the  crus  penis,  and 
runs  forward  in  the  interior  of  the  corpus  cavernosum,  by  the  side 
of  the  septum  pectiniforme.  It  ramifies  in  the  parenchyma  of  the 
venous  structure  of  the  corpus  cavernosum. 

The  Dorsal  artery  of  the  penis  ascends  between  the  two  crura  and 
symphysis  pubis  to  the  dorsum  penis,  and  runs  forward  through  the 
suspensory  ligament  in  the  groove  of  the  corpus  cavernosum  to  the 
glans,  distributing  branches  in  its  course  to  the  body  of  the  organ 
and  to  the  integument. 

The  Internal  pudic  artery  in  the  female  is  smaller  than  in  the 
male ;  its  branches,  with  their  distribution,  are  in  principle  the  same. 
The  superficial  perineal  artery  supphes  the  analogue  of  the  lateral 
half  of  the  scrotum,  viz.  the  greater  labium.  The  artery  of  the  bulb 
supphes  the  meatus  urinarius,  and  the  vestibule ;  the  artery  of  the 
corpus  cavernosum,  the  cavernous  body  of  the  clitoris,  and  the  arte- 
ria  dorsalis  clitoridis,  the  dorsum  of  that  organ. 

The  Uterine  and  Vaginal  arteries  of  the  female  are  derived 
either  from  the  internal  iliac,  or  from  the  umbilical,  internal  pudic, 
or  ischiatic  arteries.  The  former  are  very  tortuous  in  their  course, 
and  ascend  between  the  layers  of  the  broad  ligament,  to  be  distri- 
buted to  the  uterus.  The  latter  ramify  upon  the  exterior  of  the 
vagina,  and  supply  its  mucous  membrane. 

Branches  of  the  posterior  trunk. 

The  lUo-lumhar  artery  ascends  beneath  the  external  ihac  vessels 
and  psoas  muscle,  to  the  posterior  part  of  the  crest  of  the  ihum, 
where  it  divides  into  two  branches,  a  lumbar  branch  wliich  supplies 
the  psoas  and  iliacus  muscles,  and  sends  a  ramuscule  through  the 
fifth  intervertebral  foramen  to  the  spinal  cord  and  its  membranes  ; 
and  an  iliac  branch  which  passes  along  the  crest  of  the  ilium  dis- 
tributing branches  to  the  iliacus  and  abdominal  muscles,  and  inos- 
culating with  the  lumbar  and  gluteal  arteries,  and  with  the  circum- 
llexa  ilii. 

The  Obturator  Artery  is  exceedingly  variable  in  point  of 
origin ;  it  generally  proceeds  from  the  posterior  trunk  of  the  internal 
iliac  artery,  and  passes  forwards  a  little  below  the  brim  of  the  pelvis 
to  the  upper  border  of  the  obturator  foramen.  It  there  escapes 
from  the  pelvis  through  a  tendinous  arch  formed  by  the  obturator 
membrane,  and  divides  into  two  branches;  an  internal  branch 
which  curves  inwards  around  the  bony  margin  of  the  obturator 
foramen,  between  the  obturator  cxtcrnus  muscle  and  the  ramus  of 
Ihe  ischium,  and  distributes  branches  to  the  obturator  muscles,  the 
pectineus,  the  adductor  muscles,  and  to  the  organs  of  generation, 


GLUTEAL  ARTERY.  311 

and  inosculates  with  the  internal  circumflex  artery.  And  an  external 
branch  which  pursues  its  course  along  the  outer  margin  of  the 
obturator  foramen  to  the  space  between  the  gemellus  inferior  and 
quadratus  femoris,  where  it  inosculates  with  the  ischiatic  artery. 
In  its  course  backwards  it  anastomoses  with  the  internal  circumflex, 
and  sends  a  branch  through  the  notch  in  the  acetabulum  to  the  hip- 
joint.  Within  the  pelvis  the  obturator  artery  gives  off  a  branch  to 
the  ihacus  muscle,  and  a  small  ramuscule  which  inosculates  with 
the  epigastric  artery. 

The  Lateral  Sacral  Arteries  are  generally  two  in  number  on 
each  side ;  superior  and  inferior.  The  superior  passes  inwards  to 
the  first  sacral  foramen  and  is  distributed  to  the  contents  of  the 
spinal  canal,  from  which  it  escapes  by  the  posterior  sacral  foramen, 
and  supplies  the  integument  on  the  dorsum  of  the  sacrum.  The 
inferior  passes  down  by  the  side  of  the  anterior  sacral  foramina  to  the 
coccyx ;  it  first  pierces  and  then  rests  upon  the  origin  of  the  pyri- 
formis,  and  sends  branches  into  the  sacral  canal  to  supply  the  sacral 
nerves.  Both  arteries  inosculate  with  each  other  and  with  the  sacra 
media. 

The  Gluteal  Artery  is  the  continuation  of  the  posterior  trunk 
of  the  internal  iliac :  it  passes  backwards  between  the  lumbo-sacral 
and  first  lumbar  nerve  through  the  upper  part  of  the  great  sacro- 
ischiatic  foramen,  and  above  the  pyriformis  muscles,  and  divides 
into  three  branches — superficial,  deep  superior,  and  deep  inferior. 

The  Superficial  branch  is  directed  forwards  between  the  gluteus 
maximus  and  medius,  and  divides  into  numerous  branches,  which 
are  distributed  to  the  upper  part  of  the  gluteus  maximus  and  to  the 
integument  of  the  gluteal  region. 

The  Deep  superior  branch  passes  along  the  superior  curved  line 
of  the  ilium,  between  the  gluteus  medius  and  minimus  to  the  ante- 
rior superior  spinous  process,  where  it  inosculates  with  the  superfi- 
cial circumflexa  ilii  and  external  circumflex  artery.  There  are 
frequently  two  arteries  which  follow  this  course. 

The  Deep  inferior  branches  are  several  large  arteries  which 
cross  the  gluteus  minimus  obliquely  to  the  trochanter  major,  where 
they  inosculate  with  branches  of  the  external  circumflex  artery,  and 
send  branches  through  the  gluteus  minimus  to  supply  the  capsule  of 
the  hip-joint. 

Varieties  in  the  Branches  of  the  internal  iliac. — The  most  impor- 
tant of  the  varieties  occurring  among  these  branches  is  the  origin 
of  the  dorsal  artery  of  the  penis  from  the  internal  iliac  or  ischiatic. 
The  artery  in  this  case  passes  forv^^ards  by  the  side  of  the  prostate 
gland,  and  through  the  upper  part  of  the  deep  perineal  fascia.  It 
would  be  endangered  in  the  operation  for  lithotomy.  The  dorsal 
artery  of  the  penis  is  sometimes  derived  from  the  obturator,  and 
sometimes  from  one  of  the  external  pudic  arteries.  The  artery  of 
the  bulb,  in  its  normal  course,  passes  almost  transversely  inwards  to 
the  corpus  spongiosum.  Occasionally,  however,  it  is  so  oblique  in 
its  direction  as  to  render  its  division  in  lithotomy   unavoidable. 


312  EXTERNAL  ILIAC  AKTERY, 

The  obturator  artery  may  be  very  small  or  altogether  wanting,  its 
place  being  supplied  by  a  branch  from  the  external  iliac  or  epigas- 
tric. 

EXTERNAL  ILIAC  ARTERY. 

The  external  iliac  artery  of  each  side  passes  obliquely  downwards 
along  the  inner  border  of  the  psoas  muscle,  from  opposite  the  sacro- 
ihac  symphysis  to  the  femoral  arch,  where  it  becomes  the  femoral 
artery. 

Relations. — It  is  in  relation  in  front  with  the  spermatic  vessels, 
the  peritoneum,  and  a  thin  layer  of  fascia,  derived  from  the  iliac 
fascia,  which  surrounds  the  artery  and  vein.  At  its  commence- 
ment it  is  crossed  by  the  ureter,  and  near  its  termination  by  the 
crural  branch  of  the  genito-crural  nerve  and  the  circumflexa  ilii  vein. 
Externally  it  lies  against  the  psoas  muscle,  from  which  it  is  sepa- 
rated by  the  iliac  fascia ;  and  'posteriorly  it  is  in  relation  with  the 
external  iliac  vein,  which,  at  the  femoral  arch,  becomes  placed  to 
its  inner  side.  The  artery  is  surrounded  throughout  the  whole  of 
its  course  by  lymphatic  vessels  and  glands. 

Branches. — Besides  several  small  branches  which  supply  the 
glands  surrounding  the  artery,  the  external  iliac  gives  off  two 
branches,  the — 

Epigastric, 
Circumflexa  ilii. 

The  Epigastric  artery  arises  from  the  external  iliac  near  to  Pou- 
part's  ligament ;  and  passing  forwards  between  the  peritoneum  and 
transversalis  fascia,  ascends  obliquely  to  the  border  of  the  sheath  of 
the  rectus.  It  enters  the  sheath  near  to  its  lower  third,  passes 
upwards  behind  the  rectus  muscle,  to  which  it  is  distributed,  and 
in  the  substance  of  that  muscle  it  inosculates  near  the  ensiform 
cartilage  with  the  termination  of  the  internal  mammary  artery.  It 
lies  internally  to  the  internal  abdominal  ring,  and  immediately  above 
the  femoral  ring,  and  is  crossed  near  its  origin  by  the  vas  deferens 
in  the  male,  and  by  the  round  ligament  in  the  female. 

The  only  branches  of  the  epigastric  artery  worthy  of  distinct 
notice  are  the  Cremasteric,  which  accompanies  the  spermatic  cord 
and  supplies  the  cremaster  muscle;  and  the  ramusculus  which  inos- 
culates with  the  obturator  artery. 

The  Epigastric  artery  forms  a  projection  of  the  peritoneum  which 
divides  the  iliac  fossa  into  an  internal  and  an  external  portion ;  it  is 
from  the  former  that  direct  inguinal  hernia  issues,  and  from  the 
latter,  oblique  inguinal  hernia. 

The  Circumflexa  ilii  arises  from  the  outer  side  of  the  external 
iliac,  nearly  opposite  to  the  epigastric  artery.  It  ascends  obhquely 
along  Poupart's  ligament,  and  curving  around  the  crest  of  the  ilium 
between  the  attachments  of  the  internal  oblique  and  transversalis 


FEMORAL  ARTERY. 


313 


Fig.  114* 


muscle,  inosculates  with  the  ilio-lumbar  and 
inferior  lumbar  artery.  Opposite  the  anterior 
superior  spinous  process  of  the  ilium,  it  gives 
off  a  large  ascending  branch  which  passes  up- 
wards between  the  internal  oblique  and  trans- 
versalis,  and  divides  into  numerous  branches 
which  supply  the  abdominal  muscles,  and  in- 
osculates with  the  inferior  intercostal  and  with 
the  lumbar  arteries. 

Varieties  in  the  branches  of  the  external 
iliac. — The  epigastric  artery  not  unfrequent- 
ly  gives  off  the  obturator,-]-  which  descends  in 
contact  with  the  external  ihac  vein,  to  the 
obturator  foramen.  In  this  situation  the  artery 
would  lie  to  the  outer  side  of  the  femoral 
ring,  and  would  not  be  endangered  in  the 
operation  for  dividing  the  stricture  of  femoral  i^^ 
hernia.  But  occasionally  the  obturator  passes 
along  the  free  margin  of  Gimbernat's  liga- 
ment in  its  course  to  the  obturator  foramen, 
and  would  completely  encircle  the  neck  of 
the  hernial  sac  ;  a  position  in  which  it  could 
scarcely  escape  the  knife  of  the  operator. 

In  a  preparation  in  my  anatomical  collec- 
tion the  branch  of  communication  between 
the  epigastric  and  obturator  arteries  is  very 
much  enlarged,  and  takes  this  dangerous 
course. 

FEMORAL  ARTERY. 

Emerging  from  beneath  Poupart's  ligament, 
the  external  iliac  artery  enters  the  thigh  and 

*  A  view  of  the  anterior  and  inner  aspect  of  the  thigh,  showing  the  course  and 
branches  of  the  femoral  artery.  1.  The  lower  part  of  the  aponeurosis  of  the  external 
oblique  muscle  ;  its  inferior  margin  is  Poupart's  ligament.  2.  The  external  abdominal 
ring.  3,  3.  The  upper  and  lower  part  of  the  sartorius  muscle;  its  middle  portion  hav- 
ing been  removed.  4.  The  rectus.  5.  The  vastus  internus.  6.  The  patella.  7.  The 
iliacus  and  psoas  ;  the  latter  being  nearest  the  artery.  8.  The  pectineus.  9.  The 
adductor  longus.  10.  The  tendinous  canal  for  the  femoral  artery  formed  bj'  the  ad- 
ductor magnus,  and  vastus  internus  muscles.  11.  The  adductor  magnus.  12.  The 
gracilis.  13.  The  tendon  of  the  semi-tendinosus.  14.  The  femoral  artery.  15.  The 
superficial  circumflexa  ilii  artery  taking  its  course  along  the  line  of  Poupart's  ligament, 
to  the  crest  of  the  ilium.  2.  The  superficial  epigastric  artery.  1 6.  The  two  external 
pudic  arteries,  superficial  and  deep.  17.  The  profunda  artery  giving  off  1 8,  its  external 
circumflex  branch ;  and  lower  down  the  three  perforantes.  A  small  bend  of  the  inter- 
nal circumflex  artery  (8)  is  seen  behind  the  inner  margin  of  the  femoral,  just  below 
the  deep  external  pudic  artery.  19.  The  anastoinotica  magna,  descending  to  the  knee, 
upon  which  it  ramifies  (6). 

t  The  proportion  in  which  high  division  of  the  obturator  artery  from  the  epigastric 
occurs,  is  stated  to  be  one  in  three.  In  two  hundred  and  fifty  subjects  examined  by 
Cloquet  with  a  view  to  ascertain  how  frequently  the  high  division  took  place,  he  found 
the  obturator  arising  from  the  epigastric  on  both  sides  one  hundred  and  fift;y  times  ;  on 
one  side  twenty-eight  times,  and  six  times  it  arose  from  the  femoral  artery. 

40 


•314  FE3I0RAL  AETERV. 

becomes  the  femoral.  The  femoral  artery  passes  down  the  inner 
side  of  the  thigh,  from  Poupart's  ligament,  at  a  point  midway  be- 
tween the  anterior  superior  spinous  process  of  the  ilium  and  the 
symphysis  pubis,  to  the  hole  in  the  adductor  magnus,  at  the  junction 
of  the  middle  with  the  inferior  third  of  the  thigh,  where  it  becomes 
the  pophteal  artery. 

The  femoral  artery  and  vein  are  enclosed  in  a  strong  sheath, 
femoral  or  crural  canal,  which  is  formed  for  the  greater  part  of 
its  extent  by  fibrous  and  cellular  tissue,  and  by  a  process  of  fascia 
sent  inwards  from  the  fascia  lata.  Near  Poupart's  ligament  this 
sheath  is  much  larger  than  the  vessels  it  contains,  and  is  continuous 
with  the  fascia  transversalis,  and  iliac  fascia.  If  the  sheath  be 
opened  at  this  point,  the  artery  will  be  seen  to  be  situated  in  contact 
with  the  outer  wall  of  the  sheath.  The  vein  lies  next  to  the  artery, 
being  separated  from  it  by  a  fibrous  septum,  and  between  the  vein 
and  the  inner  wall  of  the  sheath,  and  divided  from  the  vein  by 
another  thin  fibrous  septum,  is  a  triangular  interval,  into  which  the 
sac  is  protruded  in  femoral  hernia.  This  space  is  occupied  in  the 
normal  state  of  the  parts  by  loose  cellular  tissue,  and  by  lymphatic 
vessels  which  pierce  the  inner  wall  of  the  sheath  to  make  their  way 
to  a  gland,  situated  in  the  femoral  ring. 

Relations. — The  upper  third  of  the  femoral  artery  is  superficial, 
being  covered  only  by  the  integument,  inguinal  glands  and  by  the 
superficial  and  deep  fascia.  The  lower  two-thirds  are  covered  by 
the  sartorius  muscle.  To  its  outer  side  the  artery  is  first  in  relation 
with  the  psoas,  next  with  the  rectus,  and  then  with  the  vastus  in- 
ternus.  Behind  it  rests  upon  the  inner  border  of  the  psoas  muscle ; 
it  is  next  separated  from  the  pectineus  by  the  femoral  vein,  profunda 
vein  and  artery,  and  then  lies  on  the  adductor  longus  to  its  termina- 
tion: near  the  lower  border  of  the  adductor  longus,  it  is  placed  in 
an  aponeurotic  canal,  formed  by  an  arch  of  tendinous  fibres,  thrown 
from  the  border  of  the  adductor  longus,  and  the  border  of  the  opening 
in  the  adductor  magnus,  to  the  side  of  the  vastus  internus.  To  its 
inner  side  it  is  in  relation  at  its  upper  part  with  the  femoral  vein, 
and  lower  down  with  the  pectineus,  the  adductor  longus,  and  sar- 
torius. 

The  immediate  relations  of  the  artery  are  the  femoral  vein,  and 
two  saphenous  nerves.  The  vein  at  Poupart's  ligament  lies  to  the 
inner  side  of  the  artery ;  but  lower  down  gets  altogether  behind  it. 
The  short  saphenous  nerve  lies  to  the  outer  side,  and  somewhat 
upon  the  sheath  for  the  lower  two-thirds  of  its  extent ;  and  the  long 
saphenous  nerve  is  situated  within  the  sheath  for  the  same  extent. 


FEMORAL  ARTKRY BRANCHES. 


315 


Plan  of  the  relations  of  the  Femoral  Artery. 

Front. 
Fascia  lata, 
Saphenous  nerves, 
Sartorius, 
Arch  of  the  tendinous  canal. 


Inner  Side. 
Femoral  vein, 
Pectineus, 
Adductor  longus, 
Sartorius. 


Femoral  artery. 


Outer  Side. 
Psoas, 
Rectus, 
Vastus  internus. 


Behind. 
Psoas  muscle. 
Femoral  vein. 
Adductor  longus. 

Branches. — The  branches  of  the  Femoral  Artery  are  the- 

Siiperficial  circumflexa  ilii, 
Superficial  epigastric, 
Superficial  external  pudic, 
Deep  external  pudic, 

(  External  circumflex, 
Profunda  <  Internal  circumflex, 


Muscular, 


Three  perforating. 


Anastomotica  magna. 

The  Superficial  circumflexa  ilii  artery  arises  from  the  femoral, 
immediately  below  Poupart's  ligament,  pierces  the  fascia  lata,  and 
passes  obliquely  towards  the  umbilicus  between  the  two  layers  of 
superficial  fascia.  It  distributes  branches  to  the  inguinal  glands  and 
integument,  and  inosculates  with  branches  of  the  deep  epigastric  and 
of  the  internal  mammary  artery. 

The  Superficial  external  pudic  arises  near  to  the  superficial  epi- 
gastric artery ;  it  pierces  the  fascia  lata,  at  the  saphenous  opening, 
and  passes  transversely  inwards  crossing  the  spermatic  cord,  to  be 
distributed  to  the  integument  of  the  penis  and  scrotum  in  the  male, 
and  to  the  labia  in  the  female. 

The  Deep  external  pudic  arises  from  the  femoral,  a  little  lower 
down  than  the  preceding  ;  it  crosses  the  femoral  vein  immediately 
below  the  termination  of  the  internal  saphenous  vein,  and  piercing 
the  pubic  portion  of  the  fascia  lata  passes  beneath  that  fascia  to  the 
inner  border  of  the  thigh,  where  it  again  pierces  the  fascia ;  having 
become  superficial,  it  is  distributed  to  the  integument  of  the  scrotum 
and  perineum. 

The  Profuivda  Femoris  arises  from  the  femoral  artery  at  two 
inches  below  Poupart's  ligament :  it  passes  downwards  and  back- 
wards, and  a  little  outwards,  behind  the  adductor  longus  muscle, 
pierces  the  adductor  magnus,  and  is  distributed  to  the  flexor  muscles 
on  the  posterior  part  of  the  thigh. 


316  PROFUNDA  ARTERY. 

Relations. — In  its  course  doM^nwards  it  rests  successively  upon 
the  pectineus,  the  conjoined  tendon  of  the  psoas  and  iUacus,  ad- 
ductor brevis  and  adductor  magnus  muscles.  To  its  outer  side  the 
tendinous  insertion  of  the  vastus  internus  muscle  intervenes  between 
it  and  the  femur;  and  in  front  it  is  separated  from  the  femoral  artery, 
above  by  the  profunda  vein  and  femoral  vein ;  and  below  by  the  ad- 
ductor longus  muscle. 

Plan  of  the  relations  of  the  Profunda  artery. 

In  Front. 
Profunda  vein, 
Adductor  longus. 

Outer  Side. 
Vastus  internus, 
Femur. 

Behind, 
Pectineus, 

Tendons  of  psoas  and  iliacus. 
Adductor  brevis, 
Adductor  magnus. 

Branches. — The  branches  of  the  profunda  artery  are  the  external 
circumflex,  internal  circumflex,  and  three  perforating  arteries. 

The  External  circumflex  artery  passes  outwards  between  the 
divisions  of  the  crural  nerve,  then  between  the  rectus  and  crureus 
muscle,  and  divides  into  three  branches  ;  ascending,  which  inos- 
culates with  the  terminal  branches  of  the  gluteal  artery ;  descending 
which  inosculates  with  the  superior  external  articular  artery ;  and 
middle,  which  continues  the  original  course  of  the  artery  around  the 
thigh,  and  anastomoses  with  branches  of  the  ischiatic,  internal  cir- 
cumflex, and  superior  perforating  artery.  It  supplies  the  muscles 
on  the  anterior  and  outer  side  of  the  thigh. 

The  Internal  circumflex  artery  is  larger  than  the  external;  it 
winds  around  the  inner  side  of  the  neck  of  the  femur,  passing  be- 
tween the  pectineus  and  psoas,  and  along  the  border  of  the  external 
obturator  muscle,  to  the  space  betv/een  the  quadratus  femoris  and 
upper  border  of  the  adductor  magnus,  where  it  anastomoses  with 
the  ischiatic,  external  circumflex,  and  superior  perforating  artery. 
It  supplies  the  muscles  on  the  upper  and  inner  side  of  the  thigh, 
anastomosing  with  the  obturator  artery,  and  sends  a  small  branch 
through  the  notch  in  the  acetabulum  into  the  hip-joint. 

The  Superior  perforating  artery  passes  backwards  between  the 
pectineus  and  adductor  brevis,  pierces  the  adductor  magnus  near  to 
the  femur,  and  is  distributed  to  the  posterior  muscles  of  the  thigh ; 
inosculating  freely  with  the  circumflex  and  ischiatic  artery,  and  with 
the  branches  of  the  middle  perforating  artery. 

The  Middle  perforating  artery  pierces  the  tendons  of  the  adductor 
brevis  and  magnus,  and  is  distributed  like  the  superior ;  inosculating 


POPLITEAL  ARTERY.  317 

with  the  superior  and  inferior  perforantes.     This  branch  frequently 
gives  off  the  nutritious  artery  of  the  femur. 

The  Inferior  ferf orating  artery  is  given  off  below  the  ad  ductor 
brevis,  and  pierces  the  tendon  of  the  adductor  magnus,  supplying  it 
and  the  flexor  muscles  and  inosculating  with  the  middle  perforating 
artery  above,  and  with  the  articular  branches  of  the  popliteal  below. 
It  is  through  the  medium  of  these  branches  that  the  collateral  cir- 
culation is  maintained  in  the  Umb  after  ligature  of  the  femoral 
*  artery. 

The  Muscular  branches  are  given  off  by  the  femoral  artery 
throughout  the  whole  of  its  course.  They  supply  the  muscles  in 
immediate  proximity  with  the  artery,  particularly  those  of  the  ante- 
rior aspect  of  the  thigh.  One  of  these  branches  larger  than  the  rest, 
arises  from  the  femoral  immediately  below  the  origin  of  the  pro- 
funda, and  passing  outwards  between  the  rectus  and  sartorius 
divides  into  branches  which  are  distributed  to  all  the  muscles  of 
the  anterior  aspect  of  the  thigh.  It  may  be  named  the  superior 
muscular  artery. 

The  Anastomotica  magna  arises  from  the  femoral  while  in  the 
tendinous  canal  formed  by  the  adductors  and  vastus  internus.  It 
runs  along  the  tendon  of  the  adductor  magnus  to  the  inner  condyle, 
and  inosculates  with  the  superior  internal  articular  artery  :  some  of 
its  branches  are  distributed  to  the  vastus  internus  muscle  and  to  the 
crureus,  and  terminate  by  anastomosing  with  the  branches  of  the 
external  circumflex  and  superior  external  articular  artery. 

POPLITEAL  ARTERY. 

The  popliteal  artery  commences  from  the  termination  of  the 
femoral  at  the  opening  in  the  adductor  magnus  muscle,  and  passes 
obliquely  outwards  through  the  middle  of  the  popliteal  space  to  the 
lower  border  of  the  popliteus  muscle,  where  it  divides  into  the  ante- 
rior and  posterior  tibial  artery. 

Relations. — In  its  course  downwards  it  rests  first  on  the  femur, 
then  on  the  posterior  ligament  of  the  knee-joint,  then  on  the  fascia, 
covering  the  popliteus  muscle.  Superficially  it  is  in  relation  with  the 
semimembranosus  muscle,  next  with  a  quantity  of  fat  which  sepa- 
rates it  from  the  deep  fascia,  and  near  its  termination  with  the  gas- 
trocnemius, plantaris,  and  soleus ;  superficial  and  external  to  it  is 
the  popliteal  vein,  and  still  more  superficial  and  external,  the  popli- 
teal nerve.  By  its  inner  side  it  is  in  relation  with  the  semimem- 
branosus, internal  condyle  of  the  femur,  and  inner  head  of  the 
gastrocnemius ;  and  by  its  outer  side  with  the  biceps,  external 
condyle  of  the  femur,  the  outer  head  of  the  gastrocnemius,  the 
plantaris  and  the  soleus. 


318 


ANTERIOR  TIBIAL  ARTERY. 


Plan  of  the  relations  of  the  PopHteal  Artery. 


Snperjicially. 

Semimembranosus, 
Popliteal  nerve, 
Popliteal  vein, 
Gastrocnemius, 
Plantaris. 
Soleus. 


Inner  Side. 
Semimembranosus, 
Internal  condyle. 
Gastrocnemius. 


Popliteal  Artery. 


Outer  Side. 
Biceps, 

External  condyle, 
Gastrocnemius, 
Plantaris, 
Soleus. 


Deeply. 
Femur, 

Ligamentum  posticum  Winslowii, 
Popliteal  fascia. 

Branches. — The  branches  of  the  popHteal  artery  are  the — 

Superior  external  articular, 
Superior  internal  articular, 
Azygos  articular, 
Inferior  external  articular. 
Inferior  internal  articular. 
Sural. 

The  Superior  articular  arteries,  external  and  internal,  wind 
around  the  femur  immediately  above  the  condyles,  to  the  front  of 
the  knee-joint,  anastomosing  with  each  other,  with  the  external  cir- 
cumflex, the  anastomotica  magna,  the  inferior  articular,  and  the 
recurrent  of  the  anterior  tibial.  The  external  passes  beneath  the 
tendon  of  the  biceps,  and  the  internal  through  an  arched  opening 
beneath  the  tendon  of  the  abductor  magnus.  They  supply  the  knee- 
joint  and  the  lower  part  of  the  feriiur. 

The  Azygos  articular  artery  pierces  the  posterior  ligament  of  the 
joint,  the  ligamentum  posticum  Winslowii,  and  supplies  the  synovial 
membrane  in  its  interior.  There  are  frequently  several  posterior 
articular  arteries. 

The  Inferior  articular  arteries  wind  around  the  head  of  the  tibia 
immediately  below  the  joint,  and  anastomose  with  each  other,  the 
superior  articular  arteries,  and  the  recurrent  of  the  anterior  tibial. 
The  external  passes  beneath  the  two  external  lateral  ligaments  of 
the  joint,  and  the  internal  beneath  the  internal  lateral  ligament. 
They  supply  the  knee-joint  and  the  heads  of  the  tibia  and  fibula. 

The  Sural  arteries  (sura,  the  calf)  are  two  large  muscular 
branches,  which  are  distributed  to  the  two  heads  of  the  gastrocne- 
mius muscle. 


ANTERIOR  TIBIAL  ARTERY. 


The  anterior  tibial  artery  passes  forwards  between  the  two  heads 
of  the  tibiahs  posticus  muscle,  and  through  the  opening  in  the  upper 


ANTERIOR  TIBIAL  ARTERY,  319 

part  of  the  interosseous  membrane,  to  the  anterior  tibial  region.  It 
then  runs  down  the  anterior  aspect  of  the  leg  to  the  ankle-joint, 
where  it  becomes  the  dorsalis  pedis. 

Relations. — In  its  course  downwards  it  rests  upon  the  interosseous 
membrane  (to  which  it  is  connected  by  a  little  tendinous  arch  which 
is  thrown  across  it),  the  lower  part  of  the  tibia,  and  the  anterior 
ligament  of  the  joint.  In  the  upper  third  of  its  course  it  is  situated 
between  the  tibialis  anticus  and  extensor  longus  digitorum,  lower 
down  between  the  tibialis  anticus  and  extensor  proprias  pollicis ;  and 
just  before  it  reaches  the  ankle  it  is  crossed  by  the  tendon  of  the 
extensor  proprius  pollicis,  and  becomes  placed  between  that  tendon 
and  the  tendons  of  the  extensor  longus  digitorum.  Its  immediate 
relations  are  the  venaB  comites  and  the  anterior  tibial  nerve,  which 
lies  at  first  to  its  outer  side,  and  at  about  the  middle  of  the  leg  be- 
comes placed  superficially  to  the  artery. 

Plan  of  the  relations  of  the  Anterior  Tibial  Artery. 

Front. 
Deep  fascia. 
Tibialis  anticus, 
Extensor  longus  digitorum, 
Extensor  proprius  pollicis, 
Anterior  tibial  nerve. 


Inner  Side. 
Tibialis  anticus, 
Tendon   of   the 
extensor    pro- 
prius pollicis. 


Anterior  Tibial 
Artery. 


Outer  Side. 
Anterior  tibial  nerve, 
Extensor  longus  digitorum. 
Extensor  proprius  pollicis, 
Tendons  of  the  extensor 
longus  digitorum. 


Behind. 
Interosseous  membrane. 
Tibia  (lower  fourth), 
Ankle  joint. 

Branches. — The  branches  of  the  Anterior  Tibial  Artery  are  the — 

Recurrent, 
Muscular, 
External  malleolar, 
Internal  malleolar. 

The  Recurrent  branch  passes  upwards  beneath  the  origin  of  the 
tibialis  anticus  muscle  to  the  front  of  the  knee-joint,  upon  which  it 
is  distributed,  anastomosing  with  the  articular  arteries. 

The  Muscular  branches  are  very  numerous,  they  supply  the  mus- 
cles of  the  anterior  tibial  region. 

The  Malleolar  arteries  are  distributed  to  the  ankle-joint;  the 
external  passing  beneath  the  tendons  of  the  extensor  longus  digi- 
torum and  peroneus  tertius,  inosculates  with  the  anterior  peroneal 
artery  and  with  the  branches  of  the  dorsalis  pedis ;  the  internal 
beneath  the  tendons  of  the  extensor  proprius  pollicis  and  tibialis 


320  DORSA.L  ARTERIES  OP  THE  FOOT. 

anticus,  inosculates  with  branches  of  the  posterior  tibial  and  of  the 
internal  plantar  artery.     They  supply  branches  to  the  ankle-joint. 

The  DoRSALis  Pedis  Artery  is  continued  forwards  along  the 
tibial  side  of  the  dorsum  of  the  foot,  from  the  ankle  to  the  base  of 
the  metatarsal  bone  of  the  great  toe,  where  it  divides  into  two 
branches,  the  dorsalis  hallucis  and  communicating. 

Relations. — The  dorsalis  pedis  is  situated  along  the  outer  border 
of  the  tendon  of  the  extensor  proprius  pollicis  ;  on  its  fibular  side  is 
the  innermost  tendon  of  the  extensor  longus  digitorum,  and  near  to 
its  termination  it  is  crossed  by  the  inner  tendon  of  the  extensor  brevis 
digitorum.  It  is  accompanied  by  venae  comites,  and  has  the  con- 
tinuation of  the  anterior  tibial  nerve  to  its  outer  side. 

Plan  of  the  relations  of  the  Dorsalis  Pedis  Artery. 

In  Front. 

Integument, 
Deep  fascia, 

Inner  tendon  of  the  extensor 
brevis  digitorum. 


Inner  Side, 
Tendon    of  the   ex- 
tensor proprius 
pollicis. 


Dorsalis  Pedis 
Artery. 


Outer  Side. 
Tendon   of   the    extensor 

longus  digitorum, 
Border    of   the     extensor 

brevis  disfitorum  muscle. 


Behind. 

Bones  of  the  tarsus,  with 
their  ligaments. 

Branches. — The  branches  of  this  artery  are  the — 

Tarsea, 

Metatarsea, — interosseas, 

Dorsalis  hallucis, — collateral  digital, 

Communicating. 

The  Tarsea  arches  transversely  across  the  tarsus,  beneath  the 
extensor  brevis  digitorum  muscle,  and  supplies  the  articulations  of 
the  tarsal  bones  and  the  outer  side  of  the  foot ;  it  anastomoses  with 
the  external  malleolar,  the  peroneal  arteries,  and  with  the  external 
plantar. 

The  Metatarsea  forms  an  arch  across  the  base  of  the  metatarsal 
bones,  and  supplies  the  outer  side  of  the  foot,  anastomosing  with  the 
tarsea  and  with  the  external  plantar  artery.  The  metatarsea  gives 
off  three  branches,  the  interossecu,  which  pass  forwards  upon  the 
dorsal  interossei  muscles,  and  divide  into  two  collateral  branches 
for  the  adjoining  toes.  At  their  commencement  these  interosseous 
branches  receive  the  posterior  perforating  arteries  from  the  plantar 
arch,  and  opposite  the  heads  of  the  metatarsal  bones  they  are  joined 
by  the  anterior  perforating  branches  from  the  digital  arteries. 


ANTERIOR  AND  POSTERIOR  TIBIALS. 
Fig.  115.*  Fig.  116.t 


321 


*  The  anterior  aspect  of  the  leg  and  foot,  showing  the  anterior  tibial  and  dorsalis 
pedis  arteries,  with  their  branches.  ].  The  tendon  of  insertion  of  the  quadriceps  ex- 
tensor muscle.  2.  The  insertion  of  the  ligamentum  patellae  into  the  lower  border  of 
the  patella.  3.  The  tibia.  4.  The  extensor  proprius  pollicis  muscle.  5.  The  extensor 
longus  digitorum.  G.  The  peronei  muscles.  7.  The  inner  belly  of  the  gastrocnemius 
and  the  soleus.  8.  The  annular  ligament  beneath  which  the  extensor  tendons  and  the 
anterior  tibial  artery  pass  into  the  dorsum  of  tlie  foot.  9.  The  anterior  tibial  artery. 
10.  Its  recurrent  branch  inosculating  with  (2)  the  inferior  articular,  and  (1)  the  superior 
articular  artery,  branches  of  the  popliteal.  11.  The  internal  malleolar  artery.  17. 
ijThe  external  malleolar  inosculating  with  the  anterior  peroneal  artery  12.  13.  The 
dorsalis  pedis  artery.  14.  The  tarsea  and  metatarsea  arteries ;  the  tarsea  is  nearest 
the  ankle,  the  metatarsea  is  seen  giving  off  the  interosseaj.  15.  The  dorsalis  hallucis 
artery.     ]  6.  The  communicating  branch. 

+  A  posterior  view  of  the  leg,  showing  the  popliteal  and  posterior  tibial  artery.  1. 
The  tendons  forming  the  inner  hamstring.  2.  The  tendon  of  the  biceps  forming  the 
outer  hamstring.  3.  The  popliteus  muscle.  4.  Tlie  flexor  longus  digitorum.  5.  The 
tibialis  posticus.  6.  The  fibula ;  immediately  below  the  figure  is  the  origin  of  the 
flexor  longus  pollicis ;  the  muscle  has  been  removed  in  order  to  expose  the  peroneal 
artery.  7.  The  peronei  muscles,  longus  and  brevis.  8.  The  lower  part  of  the  flexor 
longus  pollicis  muscle  with  its  tendon.  9.  The  popliteal  artery  giving  off  its  articular 
and  muscular  branches ;  the  two  superior  articular  are  seen  in  the  upper  part  of  the 
popliteal  space  passing  above  the  two  heads  of  the  gastrocnemius  muscle,  which  are 
cut  through  near  to  their  origin.  The  two  inferior  are  in  relation  with  the  popliteus 
muscle.  10.  The  anterior  tibial  artery  passing  througli  the  angular  interspace  between 
the  two  heads  of  the  tibialis  posticus  muscle.  11.  The  posterior  tibial  artery.  12.  The 
relative  position  of  the  tendons  and  artery  at  the  inner  ankle  from  within  outwards, 
previously  to  their  passing  beneath  the  internal  annular  ligament.  13.  The  peroneal 
artery,  dividing  into  two  branches ;  the  anterior  peroneal  is  seen  piercing  the  inter- 
osseous membrane,     14.  The  posterior  peroneal. 

41 


322 


POSTERIOE  TIBIAL  ARTERY. 


The  Dorsalis  hallucis  runs  forward  upon  the  first  dorsal  interosse- 
ous muscle,  and  at  the  base  of  the  first  phalanx  divides  into  two 
branches,  one  of  which  passes  inwards  beneath  the  tendon  of  the 
extensor  proprius  pollicis,  and  is  distributed  to  the  inner  border  of 
the  great  toe,  while  the  other  bifurcates  for  the  supply  of  the  adja- 
cent sides  of  the  great  and  second  toes. 

The  Communicating  artery  passes  into  the  sole  of  the  foot  between 
the  two  heads  of  the  first  dorsal  interosseous  muscle,  and  inosculates 
with  the  termination  of  the  external  plantar  artery. 

Besides  the  preceding,  numerous  branches  are  distributed  to  the 
bones  and  articulations  of  the  foot,  particularly  along  the  inner  bor- 
der of  the  latter. 


POSTERIOR  TIBIAL  ARTERY. 

The  posterior  tibial  artery  passes  obliquely  downwards  along  the 
tibial  side  of  the  leg  from  the  lower  border  of  the  popliteus  muscle 
to  the  concavity  of  the  os  calcis,  where  it  divides  into  the  internal 
and  external  plantar  artery. 

Relations. — In  its  course  downwards  it  lies  upon  the  tibialis  pos- 
ticus, next  upon  the  flexor  longus  digitorum,  and  then  upon  the  tibia  ; 
it  is  covered  in  by  the  intermuscular  fascia  which  separates  it  above 
from  the  soleus,  and  below  from  the  deep  fascia  of  the  leg  and  the 
integument.  It  is  accompanied  by  its  venae  comites,  and  by  the 
posterior  tibial  nerve,  which  lies  at  first  to  its  outer  side,  then  super- 
ficially to  it,  and  again  to  its  outer  side. 

Plan  of  the  relations  of  the  Posterior  Tibial  Artery. 

Superficially, 
Soleus, 
Deep  fascia, 
The  intermuscular  fascia. 


Inner  Side. 
Vein, 


Posterior  Tibial 
Artery. 


Outer  Side. 
Posterior  tibial  nerve, 
Vein. 


Deeply. 
Tibialis  posticus, 
-    Flexor  longus  digitorum, 

Tibia.  . 

Branches. — The  branches  of  the  posterior  tibial  artery  are  the — 

Peroneal, 
Nutritious, 
Muscular, 
Internal  calcanean, 
Internal  plantar. 
External  plantar. 

The  Peroneal  artery  is  given  off  from  the  posterior  tibial  at  about 
two  inches  below  the  lower  border  of  the  popliteus  muscle ;  it  is 
nearly  as  large  as  the  anterior  tibial  artery,  and  passes  obli(]ucly  out- 


PLANTAR  ARTERIES.  323 

wards  to  the  fibula.  It  then  runs  downwards  along  the  inner  border 
of  the  fibula  to  its  lower  third,  where  it  divides  into  the  anterior  and 
posterior  peroneal  artery. 

Relations. — The  peroneal  artery  rests  upon  the  tibialis  posticus 
muscle,  and  is  covered  in  by  the  soleus,  the  intermuscular  fascia,  and 
the  flexor  longus  pollicis,  having  the  fibula  to  its  outer  side. 

,    Plan  of  the  relations  of  the  Peroneal  Artery. 

In  Front. 
Soleus, 

Intermuscular  fascia, 
Flexor  longus  pollicis. 

Outer  Side. 
Fibula. 

Behind, 
Tibialis  posticus. 

Branches. — The  branches  of  the  peroneal  artery  are  muscular  to 
the  neighbouring  muscles,  particularly  to  the  soleus,  and  the  two 
terminal  branches  anterior  and  posterior  peroneal. 

The  Anterior  peroneal  pierces  the  interosseous  membrane  at  the 
lower  third  of  the  leg,  and  is  distributed  on  the  front  of  the  outer 
malleolus,  anastomosing  with  the  external  malleolar  and  tarsal  artery. 
This  branch  is  very  variable  in  size. 

The  Posterior  'peroneal  continues  onwards  along  the  posterior 
aspect  of  the  outer  malleolus  to  the  side  of  the  os  calcis,  to  which 
and  to  the  muscles  arising  from  it,  it  distributes  external  calcanean 
branches.  It  anastomoses  with  the  anterior  peroneal,  tarsal,  exter- 
nal plantar,  and  posterior  tibial  artery. 

The  JVutritious  artery  of  the  tibia  arises  from  the  trunk  of  the 
tibial,  frequently  above  the  origin  of  the  peroneal,  and  proceeds  to 
the  nutritious  canal  which  it  traverses  obliquely  from  below  upwards. 

The  Muscular  brandies  of  the  posterior  tibial  artery  are  distributed 
to  the  soleus  and  to  the  deep  muscles  on  the  posterior  aspect  of  the 
leg.  One  of  these  branches  is  deserving  of  notice,  a  recurrent 
5mnc/?,  which -arises  from  the  posterior  tibial  above  the  origin 
of  the  peroneal  artery,  pierces  the  soleus  and  is  distributed  upon  the 
inner  side  of  the  tibia,  anastomosing  with  the  inferior  internal 
articular. 

The  Internal  calcanean  branches,  three  or  four  in  number,  proceed 
from  the  posterior  tibial  artery  immediately  before  its  division ;  they 
are  distributed  to  the  inner  side  of  the  os  calcis,  to  the  integument, 
and  to  the  muscles  which  arise  from  its  inner  tuberosity,  and  they 
anastomose  with  the  external  calcanean  branches,  and  with  all  the 
neighbouring  arteries. 

PLANTAR  ARTERIES. 

The  Internal  plantar  artery  proceeds  from  the  bifurcation  of  the 
posterior  tibial  at  the  inner  malleolus  and  passes  along  the  inner 


324 


PLANTAR  ARTERIES. 


border  of  the  foot  between  the  abductor  pollicis  and  flexor  brevis 
digitorum  muscles,  supplying  the  inner  border  of  the  foot  and 
greaftoe. 

The  External  plantar  artery,  much  larger  than  the  internal, 
passes  obliquely  outwards  between  the  first  and  second  layers  of  the 
plantar  muscles,  to  the  fifth  metatarsal  space.  It  then  turns  hori- 
zontally inwards  between  the  second  and  third  layers,  to  the  first 
metatarsal  space,  where  it  inosculates  with  the  communicating 
branch  from  the  dorsalis  pedis.  The  horizontal  portion  of  the 
artery  describes  a  slight  curve,  having  the  convexity  forwards;  this 
is  the  plantar  arch. 

Branches. — The  branches  of  the  external  Fig.  117.* 

plantar  artery  are  the — 

Muscular, 

Articular, 

Digital, — anterior  perforating, 

Posterior  perforating. 

The  Muscular  branches  are  distributed  to 
the  muscles  in  the  sole  of  the  foot. 

The  Articular  branches  supply  the  ligaments 
of  the  articulations  of  the  tarsus,  and  their 
synovial  membranes. 

The  Digital  branches  are  four  in  number: — 
the  first  is  distributed  to  the  outer  side  of  the 
little  toe ;  the  three  others  pass  forwards  to  the 
cleft  between  the  toes,  and  divide  into  collateral 
branches,  which  supply  the  adjacent  sides  of 
the  three  external  toes  and  the  outer  side  of 
the  second.  At  the  bifurcation  of  the  toes,  a 
small  branch  is  sent  upwards  from  each 
digital  artery,  to  inosculate  with  the  inter- 
osseous branches  of  the  metatarsea;  these  are  the  anterior  perforating 
arteries. 

The  Posterior  perforating  are  three  small  branches  which  pass 
upwards  between  the  heads  of  the  three  external  dorsal  interossei 
muscles,  to  inosculate  with  the  arch  formed  by  the  metatarsea 
artery. 

Varieties  in  the  Arteries  of  the  lower  Extremity. — The  femoral 
artery  occasionally  divides  at  Poupart's  ligament  into  two  branches, 
and  sometimes  into  three ;  the  former  is  an  instance  of  the  high 
division  of  the  profunda  artery ;  and  in  a  case  of  the  latter  kind 


*  The  arteries  of  the  sole  of  the  foot;  the  first  and  a  part  of  the  second  layer  of  mus- 
cles havinjr  been  removed.  1.  The  under  and  posterior  i)art  of  the  os  calcis;  to  whicii 
the  origins  of  the  first  layer  of  niuscles  remain  attached.  2.  The  musculus  accesso- 
rius.  3.  Tlic  long  flexor  tendons.  4.  The  tendon  of  the  peroneus  long-us.  .5.  The 
termination  of  the  posterior  tibial  artery.  G.  Tlie  internal  plantar.  7.  The  external 
plantar  artery.  8.  The  plantar  arcli  ffivinj(  off  four  digital  branches,  which  pass  for- 
wards on  the  interossei  muscles  to  divide  into  collatf:ral  branches. 


PULMONARY  ARTERY.  325 

which  occurred  during  my  dissections,  the  branches  were  the  pro- 
funda, the  superficial  femoral,  and  internal  circumflex  artery.  Dr. 
Quain  in  his  "  Elements  of  Anatomy,"  records  an  instance  of  a  high 
division  of  the  femoral  artery,  in  which  the  two  vessels  became 
again  united  in  the  popliteal  region.  The  point  of  origin  of  the  pro- 
funda artery  varies  considerably  in  different  subjects,  being  some- 
times nearer  to  and  sometimes  farther  from  Poupart's  ligament,  but 
more  frequently  the  former.  The  branches  of  the  popliteal  artery 
are  very  liable  to  variety  in  size ;  and  in  all  these  cases  the  com- 
pensating principle,  so  constant  in  the  vascular  system,  is  strikingly 
manifested.  When  the  anterior  tibial  is  of  small  size,  the  peroneal 
is  large ;  and,  in  place  of  dividing  into  two  terminal  branches  at 
the  lower  third  of  the  leg,  descends  to  the  lower  part  of  the  inter- 
osseous membrane,  and  emerges  upon  the  front  of  the  ankle,  to 
supply  the  dorsum  of  the  foot :  or  the  posterior  tibial  and  plantar 
arteries  are  large,  and  the  external  plantar  is  continued  between  the 
heads  of  the  first  dorsal  interosseous  muscle,  to  be  distributed  to  the 
dorsal  surface  of  the  foot.  Sometimes  the  posterior  tibial  artery  is 
small  and  thread-like;  and  the  peroneal,  after  descending  to  the 
ankle,  curves  inwards  to  the  inner  malleolus,  and  divides  into  the 
two  plantar  arteries.  If  in  this  case  the  posterior  tibial  be  suffi- 
ciently large  to  reach  the  ankle,  it  inosculates  with  the  peroneal 
previously  to  its  division.  The  internal  plantar  artery  sometimes 
takes  the  distribution  of  the  external  plantar,  which  is  short  and 
diminutive,  and  the  latter  not  unfrequently  replaces  a  deficient  dor- 
salis  pedis. 

The  varieties  of  arteries  are  interesting  in  the  practical  applica- 
tion of  a  knowledge  of  their  principal  forms  to  surgical  operations  ; 
in  their  transcendental  anatomy,  as  illustrating  the  normal  distribu- 
tion in  animals ;  or  in  many  cases,  as  diverticula  permitted  by 
Nature,  to  teach  her  observers  two  important  principles  •.—first,  in 
respect  to  herself,  that,  however,  in  her  means  she  may  indulge  in 
change,  the  end  is  never  overlooked,  and  a  hmb  is  as  surely  sup- 
plied by  a  leash  of  arteries,  various  in  their  course,  as  by  those 
which  we  are  pleased  to  consider  normal  in  distribution ;  and 
secondly,  with  regard  to  us ;  that  we  should  ever  be  keenly  alive  to 
what  is  passing  beneath  our  observation,  and  ever  ready  in  the 
most  serious  operation  to  deviate  from  our  course  and  avoid, — or 
give  eyes  to  our  knife,  that  it  may  see — the  concealed  dangers 
which  it  is  our  pride  to  be  able  to  contend  with  and  vanquish. 

PULMONARY  ARTERY. 

The  pulmonary  artery  arises  from  the  left  side  of  the  base  of  the 
right  ventricle  in  front  of  the  origin  of  the  aorta,  and  ascends 
obliquely  to  the  under  surface  of  the  arch  of  the  aorta,  where  it 
divides  into  the  right  and  left  pulmonary  arteries.  In  its  course 
upwards  and  backwards  it  inclines  to  the  left  side,  crossing  the 
commencement  of  the  aorta,  and  is  connected  to  the  under  surface 


326  PULMONARY  AKTERY. 

of  the  arch  by  a  hgamentous  cord,  the  remains  of  the  ductus  arte- 
riosus. 

Relations. — It  is  enclosed  for  one  half  of  its  extent  by  the  pericar- 
dium, and  receives  the  attachment  of  the  fibrous  portion  of  the  peri- 
cardium by  its  upper  portion.  Behind,  it  rests  against  the  ascend- 
ing aorta ;  on  either  side  is  the  appendix  of  the  corresponding 
auricle  and  a  coronary  artery ;  and  above,  the  cardiac  ganglion 
and  the  remains  of  the  ductus  arteriosus. 

The  Right  pulmonary  artery  passes  beneath  the  arch  and  behind 
the  ascending  aoita,  and  in  the  root  of  the  lungs  divides  into  three 
branches  for  the  three  lobes. 

The  Left  pulmonary  artery,  rather  larger  than  the  right,  passes  in 
front  of  the  descending  aorta,  to  the  root  of  the  left  lung  to  which  it 
is  distributed.  These  arteries  divide  and  subdivide  in  the  structure 
of  the  lungs,  and  terminate  in  capillary  vessels  which  form  a  net- 
work around  the  bronchial  cells,  and  become  continuous  with  the 
radicles  of  the  pulmonary  veins. 

Relations. — In  the  root  of  the  right  lung  examined  trom  above 
downwards,  the  pulmonary  artery  is  situated  between  the  bronchus, 
and  pulmonary  veins ;  the  former  being  above,  the  latter  below ; 
while  in  the  left  lung  the  artery  is  the  highest,  next  the  bronchus, 
and  then  the  veins.  On  both  sides,  from  before  backwards,  the 
artery  is  situated  between  the  veins  and  bronchi,  the  former  being 
in  front,  and  the  latter  behind. 


CHAPTER   VI. 


ON  THE  VEINS. 


The  veins  are  the  vessels  which  return  the  blood  to  the  auricles 
of  the  heart,  after  it  has  been  circulated  by  the  arteries  through  the 
various  tissues  of  the  body.  They  are  much  thinner  in  structure 
than  the  arteries,  so  that  when  emptied  of  their  blood  they  become 
flattened  and  collapsed.  The  veins  of  the  systemic  circulation 
convey  the  dark-coloured  and  impure  or  venous  hloocl  from  the 
capillary  system  to  the  right  auricle  of  the  heart,  and  they  are 
found  after  death  to  be  more  or  less  distended  with  that  fluid.  The 
veins  of  the  pulmonary  circulation  resemble  the  arteries  of  the 
systemic  circulation  in  containing  during  hfe  the  pure  or  arterial 
blood,  which  they  transmit  from  the  capillaries  of  the  lungs  to  the 
left  auricle. 

The  veins  commence  by  minute  radicles  in  the  capillaries  which 
are  every  where  distributed  through  the  textures  of  the  body,  and 
converge  to  constitute  larger  and  larger  branches,  till  they  termi- 
nate in  the  large  trunks  which  convey  the  venous  blood  directly  to 
the  heart.  In  diameter  they  are  much  larger  than  the  arteries,  and 
like  those  vessels  their  combined  areas  would  constitute  an  imagi- 
nary cone,  whereof  the  apex  is  placed  at  the  heart,  and  the  base  at 
the  surface  of  the  body.  It  follows  from  this  arrangement,  that  the 
blood  in  returning  to  the  heart  is  passing  from  a  larger  into  a  smaller 
channel,  and  therefore  increases  in  rapidity  during  its  course. 

Veins  admit  of  a  threefold  division,  into  superficial,  deep,  and 
sinuses. 

The  Superficial  veins  return  the  blood  from  the  integument  and 
superficial  structures,  and  take  their  course  between  the  layers  of 
the  superficial  fascia ;  they  then  pierce  the  deep  fascia  in  the  most 
convenient  and  protected  situations,  and  terminate  in  the  deep 
veins.  They  are  unaccompanied  by  arteries,  and  are  the  vessels 
usually  selected  for  venesection. 

The  Deep  veins  are  situated  among  the  deeper  structures  of  the 
body  and  generally  in  relation  with  the  arteries ;  in  the  limbs  they 
are  enclosed  in  the  same  sheath  with  those  vessels,  and  they  return 
the  venous  blood  from  the  capillaries  of  the  deep  tissues.  In  com- 
pany with  all  the  smaller,  and  also  with  the  secondary  arteries,  as 
the  brachial,  radial,  and  ulnar  in  the  upper,  and  the  tibial  and  pero- 
neal in  the  lower  extremity,  there  are  two  veins,  placed  one  on  each 


328  STRUCTURE  OF  VEINS. 

side  of  the  artery,  and  named  vencB  comites.  The  larger  arteries,  as 
the  axillary,  subclavian,  carotid,  popliteal,  femoral,  &c.,  are  accom- 
panied by  a  single  venous  trunk.  Sinuses  differ  from  veins  in  their 
structure,  and  also  in  their  mode  of  distribution,  being  confined  to 
especial  organs,  situated  within  their  substance.  The  principal  venous 
sinuses  are  those  of  the  dura  mater,  of  the  diploe,  of  the  cancellous 
structure  of  bone,  and  of  the  uterus. 

The  communications  between  veins  are  even  more  frequent  than 
those  of  arteries,  and  they  take  place  between  the  larger  as  well 
as  among  the  smaller  vessels ;  the  vense  comites  communicate  with 
each  other  very  frequently  in  their  course,  by  means  of  short  trans- 
verse branches  which  pass  from  one  to  the  other.  These  communi- 
cations are  strikingly  exhibited  in  the  frequent  inosculations  of  the 
spinal  veins,  and  in  the  various  venous  plexuses,  as  the  spermatic 
plexus,  vesical  plexus,  &c.  The  office  of  these  inosculations  is  very 
apparent,  as  tending  to  obviate  the  obstructions  to  wliich  the  veins 
are  particularly  liable  from  the  thinness  of  their  coats,  and  from  their 
inability  to  overcome  much  impediment  by  the  force  of  their 
current. 

Veins  are  composed  of  three  tunics,  external,  middle,  and  in- 
ternal. 

The  External  or  Cellular  coat  is  dense  and  resisting,  and  resem- 
bles the  cellular  tunic  of  arteries.  The  middle  coat  is  fibrous  like 
that  of  arteries,  but  extremely  thin ;  so  that  its  existence  is  ques- 
tioned by  some  anatomists.  The  internal  coat  is  serous,  and  also 
similar  to  that  of  arteries ;  it  is  continuous  with  the  lining  membrane 
of  the  heart  at  one  extremity,  and  with  the  lining  of  the  capillaries 
at  the  other.  At  certain  intervals  the  internal  coat  forms  folds  or 
duplicatures,  which  constitute  valves.  The  valves  of  veins  are 
generally  composed  of  two  semilunar  folds,  one  on  each  side  of 
the  cylinder  of  the  vessel,  occasionally  of  a  single  duplicature, 
having  a  spiral  direction,  and  in  rare  instances  of  three.  The  free 
extremity  of  the  valvular  folds  is  concave,  and  directed  forwards, 
so  that  while  the  current  of  blood  would  be  permitted  to  flow  freely 
towards  the  heart,  the  valves  would  become  distended  and  the  current 
intercepted  if  the  stream  became  retrograde  in  its  course.  Upon  the 
cardiac  side  of  each  valve  the  vein  is  expanded  into  two  pouches 
(sinuses),  corresponding  with  the  segments  of  the  valves,  which  give 
to  the  distended  or  injected  vein  a  knotted  appearance.  The  valves 
are  most  numerous  in  the  veins  of  the  extremities,  particularly  in  the 
deeper  veins,  and  they  are  generally  absent  in  the  smaller  veins, 
and  in  the  veins  of  the  viscera,  as  in  the  portal  and  cerebral  veins : 
they  are  also  absent  in  the  large  trunks,  as  in  the  venge  cavse,  vena) 
azygos,  innominata),  and  iliac  veins. 

Sinuses  are  venous  channels,  excavated  in  the  structure  of  an 
organ,  and  lined  by  the  internal  coat  of  the  veins ;  of  this  structure 
are  the  sinuses  of  the  dura  matter,  whose  external  covering  is  the 
fibrous  tissue  of  the  membrane,  and  the  internal,  the  serous  layer  of 


VEINS  OF  THE  HEAD  AND  NECK.  329 

the  veins.  The  external  investment  of  the  sinuses  of  the  uterus  is 
the  tissue  of  that  organ ;  and  that  of  the  bones,  the  hning  membrane 
of  the  cells  and  canals. 

Veins,  like  arteries,  are  supplied  with  nutritious  vessels,  the  vasa 
vasorum ;  and  it  is  to  be  presumed  that  nervous  filaments  are  dis- 
tributed to  their  coats. 

I  shall  describe  the  veins  according  to  the  primary  division  of 
the  body ;  taking  first,  those  of  the  head  and  neck ;  next  those  of 
the  upper  extremity ;  then  those  of  the  lower  extremity ;  and  lastly, 
the  veins  of  the  trunk. 


VEINS  OF  THE  HEAD  AND  NECK. 

The  veins  of  the  head  and  neck  may  be  arranged  into  three 
groups,  viz.  1.  Veins  of  the  exterior  of  the  head.  2.  Veins  of  the 
diploe  and  interior  of  the  cranium.     3.  Veins  of  the  neck. 

The  veins  of  the  exterior  of  the  head  are  the — 

Facial, 

Internal  maxillary, 

Temporal, 

Temporo-maxillary, 

Posterior  auricular, 

Occipital. 

The  Facial  vein  commences  upon  the  anterior  part  of  the  skull 
in  a  venous  plexus,  formed  by  the  communications  of  the  branches 
of  the  temporal,  and  descends  along  the  middle  line  of  the  fore- 
head, under  the  name  oi  frontal  vein,  to  the  root  of  the  nose,  where 
it  is  connected  with  its  fellow  of  the  opposite  side  by  a  communi- 
cating trunk  which  constitutes  the  nasal  arch.  There  are  usually 
two  frontal  veins  which  communicate  by  a  transverse  inosculation ; 
but  sometimes  the  vein  is  single  and  bifurcates  at  the  root  of  the 
nose,  into  the  two  angular  veins.  From  the  nasal  arch,  the  frontal 
is  continued  downwards  by  the  side  of  the  root  of  the  nose,  under 
the  name  of  the  angular  vein ;  it  then  passes  beneath  the  zygomatic 
muscles  and  becomes  the  facial  vein,  and  descends  along  the  ante- 
rior border  of  the  masseter  muscle,  crossing  the  body  of  the  lower 
jaw,  by  the  side  of  the  facial  artery,  to  the  submaxillary  gland, 
and  from  thence  to  the  internal  jugular  vein  in  which  it  ter- 
minates. 

The  branches  which  the  facial  vein  receives  in  its  course  are,  the 
supra- orbital,  which  joins  the  frontal  vein ;  the  dorsal  veins  of  the 
nose  which  terminate  in  the  nasal  arch ;  the  ophthalmic,  which  com- 
municates with  the  angular  vein ;  the  palpebral  and  nasal,  which 
also  open  into  the  angular  vein ;  a  considerable  trunk,  the  alveolar, 
which  returns  the  blood  from  the  spheno-maxillary  fossa,  from  the 
infra-orbital,  palatine,  vidian  and  spheno-palatinc,  and  joins  the 
facial  beneath  the  zygomatic  process  of  the  superior  maxillary 

42 


830  VEINS  OF  THE  DIPLOE. 

bone,  and  the  veins  corresponding  with  the  branches  of  the  facial 
artery. 

The  Internal  maxillary  vein  receives  the  branches  from  the 
zygomatic  and  pterygoid  fossoe  ;  these  are  so  numerous  and  com- 
municate so  freely  as  to  constitute  a  pterygoid  plexus.  Passing 
backwards  behind  the  neck  of  the  lower  jaw,  the  internal  maxillary 
joins  with  the  temporal  vein,  and  the  common  trunk  resulting  from 
this  union  constitutes  the  temforo-maxillary  vein. 

The  Temporal  vein  commences  on  the  vertex  of  the  head  by  a 
plexiform  network  which  is  continuous  with  the  frontal,  the  tem- 
poral, auricular,  and  occipital  veins.  The  ramifications  of  this 
plexus  form  an  anterior  and  a  posterior  branch  which  unite  imme- 
diately above  the  zygoma ;  the  trunk  is  here  joined  by  another  large 
vein,  the  middle  temporal,  which  collects  the  blood  from  the  temporal 
muscle,  and  around  the  outer  segment  of  the  orbit,  and  pierces  the 
temporal  fascia  near  the  root  of  the  zygoma.  The  temporal  vein 
then  descends  between  the  meatus  auditorius  externus  and  the  con- 
dyle of  the  lower  jaw,  and  unites  with  the  internal  maxillary  vein, 
to  form  the  temporo-maxillary. 

The  Temporo-maxillary  vein  formed  by  the  union  of  the  temporal 
and  internal  maxillary,  passes  downwards  in  the  substance  of  the 
parotid  gland  to  its  lower  border,  where  it  becomes  the  external 
jugular  vein.  It  receives  in  its  course  the  anterior  auricular,  masse- 
teric, transverse  facial,  and  parotid  veins,  and  near  its  termination 
is  joined  by  the  posterior  auricular  vein. 

The  Posterior  auricular  vein  communicates  with  the  plexus  upon 
the  vertex  of  the  head,  and  descends  behind  the  ear  to  the  temporo- 
maxillary  vein,  immediately  before  that  vessel  merges  in  the  external 
jugular.  It  receives  in  its  course  the  veins  from  the  external  ear 
and  the  stylo-mastoid  vein. 

The  Occipital  vein  commencing  posteriorly  in  the  plexus  of  the 
vertex  of  the  head,  follows  the  direction  of  the  occipital  artery,  and 
passing  deeply  beneath  the  muscles  of  the  back  part  of  the  neck, 
terminates  in  the  external  jugular  vein.  This  vein  communicates 
with  the  lateral  sinus  by  means  of  a  large  branch  which  passes 
through  the  mastoid  foramen,  the  mastoid  vein. 

VEINS  OF  THE  DIPLOE. 

The  diploe  of  the  bones  of  the  head  is  furnished  in  the  adult  with 
irregular  sinuses,  which  are  formed  by  a  continuation  of  the  sei'ous 
membrane  of  the  veins  into  the  osseous  canals  in  which  they  are 
lodged.  At  the  middle  period  of  life  these  sinuses  are  confined  to 
the  particular  bones ;  but  in  old  age,  after  the  ossification  of  the 
sutures,  they  may  be  traced  from  one  bone  to  the  next.  They  receive 
their  blood  from  the  capillaries  supplying  the  cellular  structure  of 
the  diploe,  and  terminate  externally  in  the  veins  of  the  pericranium, 
and  internally  in  the  veins  and  sinuses  of  tlie  dura  mater.     These 


CEREBRAL  AND  CEREBELLAR  VEINS.  331 

veins  are  separated  from  the  bony  walls  of  the  canals  by  a  thin 
layer  of,  marrow. 

CEREBRAL  AND  CEREBELLAR  VEINS. 

The  cerebral  veins  are  remarkable  for  the  absence  of  valves,  and 
for  the  extreme  tenuity  of  their  coats.  They  may  be  divided  into 
the  superficial,  and  deep  or  ventricular  veins. 

The  Superficial  cerebral  veins  are  situated  upon  the  surface  of  the 
hemispheres,  lying  in  the  grooves  formed  by  the  convexities  of  the 
convolutions.  They  are  named  from  the  position  which  they  may 
chance  to  occupy  upon  the  surface  of  this  organ,  either  superior  or 
inferior,  internal  or  external,  anterior  or  posterior. 

The  Superior  cerebral  veins,  seven  or  eight  in  number  on  each 
side,  pass  obliquely  forwards,  and  terminate  in  the  superior  longitu- 
dinal sinus,  in  the  opposite  direction  to  the  course  of  the  stream  of 
blood  in  the  sinus. 

The  Deep  or  Ventricular  veins  commence  within  the  lateral  ven- 
tricles by  two  vessels,  the  vena  corporis  striati  and  the  veins  of  the 
choroid  plexus,  which  unite  to  form  the  two  vense  Galeni. 

The  VencB  Galeni  pass  backwards  in  the  structure  of  the  velum 
interpositum ;  and  escaping  through  the  fissure  of  Bichat,  terminate 
in  the  straight  sinus. 

The  Cerebellar  veins  are  disposed,  like  those  of  the  cerebrum,  on 
the  surface  of  the  lobes  of  the  cerebellum ;  they  are  situated  some 
upon  the  superior,  and  some  upon  the  inferior  surface,  while  others 
occupy  the  borders  of  the  organ.  They  terminate  in  the  lateral 
and  petrosal  sinuses. 

SINUSES  OF  THE  DURA  MATER. 

The  sinuses  of  the  dura  mater  are  irregular  channels,  formed  by 
the  splitting  of  the  layers  of  that  membrane,  and  fined  upon  their 
inner  surface  by  a  continuation  of  the  serous  layer  of  the  veins. 
They  may  be  divided  into  two  groups: — 1.  Those  situated  at  the 
upper  and  back  part  of  the  skull.  2.  The  sinuses  at  the  base  of  the 
skull.     The  former  are,  the — 

Superior  longitudinal  sinus, 
Inferior  longitudinal  sinus, 
Straight  sinus,  or  sinus  quartus, 
Occipital  sinuses. 
Lateral  sinuses. 

The  Superior  longitudinal  sinus,  is  situated  in  the  attached  margin 
of  the  falx  cerebri,  and  extends  along  the  middle  line  of  the  arch  of 
the  skull,  from  the  foramen  ca3cum  in  the  frontal,  to  the  inner  tube- 
rosity of  the  occipital  bone,  where  it  divides  into  the  two  lateral 
sinuses.  It  is  triangular  in  form,  is  small  in  front,  and  increases 
gradually  in  size  as  it  passes  backwards ;  it  receives  the  superior 
cerebral  veins  which  open  into  it  obliquely,  numerous  small  veins 


332 


INFERIOR  LONGITUDINAL  SINUS, 


from  the  diploe,  and  near  the  posterior  extremity  of  the  sagittal 
sutm'e  the  parietal  veins,  from  the  pericranium  and  scalp.  Examined 
upon  its  interior,  it  presents  numerous  transverse  fibrous  bands,  the 
chordae  Willisii,  which  are  stretched  across  its  inferior  angle  ;  and 
some  small  white  granular  masses,  the  glandular  Pacchioni ;  the 
oblique  openings  of  the  cerebral  veins,  with  their  valve-Uke  margin, 
are  also  seen  upon  the  walls  of  the  sinus. 

The  termination  of  the  superior  longitudinal  sinus  in  the  two 
lateral  sinuses  forms  a  considerable  dilatation,  into  which  the  straight 
sinus  opens  from  the  front,  and  the  occipital  sinuses  from  below. 
This  dilatation  is  named  the  torcular  He?-ophili,*  and  is  the  point  of 
communication  of  six  sinuses — the  superior  longitudinal,  tv/o  lateral, 
two  occipital,  and  the  straight. 

Fig.  iiat 


The  Inferior  longitudinal  sinus  is  situated  in  the  free  margin  of  the 
falx  cerebri ;  it  is  cylindrical  in  form,  and  extends  from  near  the 
crista  galli  to  the  anterior  border  of  the  tentorium,  where  it  termi- 
nates in  the  straight  sinus.  It  receives  in  its  course  several  veins 
from  the  falx. 

The  Straight  or  fourth  sinus  is  the  sinus  of  the  tentorium  ;  it  is 
situated  at  the  line  of  union  of  the  falx  with  the  tentorium  ;  is 
prismoid  in  form,  and  extends  across  the  tentorium,  from  the  termina- 

*  Torcular  (a  pi-ess),  from  a  supposition  entertained  by  the  older  anatomists  that  the 
columns  of  blood,  coming  in  different  directions,  compressed  each  other  at  this  point, 

t  Tiie  sinuses  of  the  upper  and  back  part  of  the  skull.  1.  The  superior  longitudinal 
sinus.  2,  2.  The  cerebral  veins  opening  into  tlie  sinus  from  btihind  forwards.  3.  The 
falx  cerebri.  4.  The  inferior  longitudinal  sinus.  5.  The  straight  or  fourth  sinus.  6. 
The  vcnaj  Galeni.  7.  The  torcular  Herophili.  8.  The  two  lateral  sinuses,  with  the 
occipital  sinuses  between  them.  9.  The  termination  of  the  inferior  petrosal  sinus  of 
one  side.  10.  The  dilatations  corresponding  with  the  jugular  fossae.  11.  The  internal 
jugular  veins. 


LATERAL  SINUSES.  333 

tion  of  the  inferior  longitudinal  sinus  to  the  torcular  Herophili.  It 
receives  the  venag  Galeni,  the  cerebral  veins  from  the  inferior  part 
of  the  posterior  lobes,  and  the  superior  cerebellar  veins. 

The  Occipital  sinuses  are  two  canals  of  small  size,  situated  in  the 
attached  border  of  the  falx  cerebelli ;  they  commence  by  several 
small  veins  around  the  foramen  magnum,  and  terminate  by  separate 
openings  in  the  torcular  Herophili.  They  not  unfrequently  commu- 
nicate with  the  termination  of  the  lateral  sinuses. 

The  Lateral  sinuses,  commencing  at  the  torcular  Herophili,  pass 
horizontally  outwards,  in  the  attached  margin  of  the  tentorium,  and 
curve  downwards  and  inwards  along  the  base  of  the  petrous  portion 
of  the  temporal  bone,  at  each  side,  to  the  foramina  lacera  posteriora, 
where  they  terminate  in  the  internal  jugular  veins.  Each  sinus  rests 
successively  in  its  course  upon  the  transverse  groove  of  the  occipital 
bone,  posterior  inferior  angle  of  the  parietal,  mastoid  portion  of  the 
temporal,  and  again  on  the  occipital  bone.  They  receive  the  cerebral 
veins  from  the  inferior  surface  of  the  posterior  lobes,  the  inferior 
cerebellar  veins,  the  superior  petrosal  sinuses,  the  mastoid,  and  pos- 
terior condyloid  veins,  and,  at  their  termination,  the  inferior  petrosal 
sinuses.  These  sinuses  are  often  unequal  in  size,  the  right  being 
much  larger  than  the  left. 

The  sinuses  of  the  base  of  the  skull  are  the — 

Cavernous, 
Inferior  petrosal, 
Circular, 

Superior  petrosal, 
Transverse. 

The  Cavernous  sinuses  are  named  from  presenting  a  cellular  struc- 
ture in  their  interior.  They  are  situated  on  each  side  of  the  sella 
turcica,  receiving,  anteriorly,  the  ophthalmic  veins  through  the 
sphenoidal  fissures,  and  terminating  posteriorly  in  the  inferior  petrosal 
sinuses.  In  the  internal  wall  of  each  cavernous  sinus  is  the  internal 
carotid  artery,  accompanied  by  several  filaments  of  the  carotid  plexus, 
and  crossed  by  the  sixth  nerve ;  and,  in  its  external  wall,  the  third, 
fourth,  and  ophthalmic  nerves.  These  structures  are  separated  from 
the  blood  flowing  through  the  sinus,  by  the  tubular  lining  membrane. 
The  cerebral  veins  from  the  under  surface  of  the  anterior  lobes, 
open  into  the  cavernous  sinuses.  They  communicate  by  means  of 
the  ophthalmic  veins  with  the  facial  veins,  by  the  circular  sinus  with 
each  other,  and  by  the  superior  petrosal  with  the  lateral  sinuses. 

The  Inferior  petrosal  sinuses  are  the  continuations  of  the  cavern- 
ous sinuses  backwards  along  the  lower  border  of  the  petrous  por- 
tion of  the  temporal  bone  at  each  side  of  the  base  of  the  skull,  to 
the  foramina  lacera  posteriora,  where  they  terminate  with  the  lateral 
sinuses  in  the  commencement  of  the  internal  jugular  veins. 

The  Circular  sinus  is  situated  in  the  sella  turcica,  surrounding  the 
pituitary  gland,  and  commimicates  on  each  side  with  the  cavernous 
sinus. 


334 


VEINS  or  THE  NECK. 


The  Sifperior  petrosal  sinuses  pass  obliquely  backwards  along  the 
attached  border  of  the  tentorium,  on  the  upper  margin  of  the  petrous 
portion  of  the  temporal  bone,  and  establish  a  communication  between 
the  cavernous  and  lateral  sinus  at  each  side.  They  receive  one  or 
two  cerebral  veins  from  the  inferior  part  of  the  middle  lobes,  and  a 
cerebellar  vein  from  tiie  anterior  border  of  the  cerebellum. 


Fig-.  119.* 


The  Transverse  sinus  (basilar,  anterior  occipital)  passes  trans- 
versely across  the  basilar  process  of  the  occipital  bone,  forming  a 
communication  between  the  two  inferior  petrosal  sinuses. 


VEINS  OF  THE  NECK. 

The  veins  of  the  neck  which  return  the  blood  from  the  head  are 
the— 

External  jugular, 
Anterior  jugular. 
Internal  jugular, 
Vertebral. 

The  External  jugular  vein  is  formed  by  the  union  of  the  pos- 
terior auricular  vein  with  the  temporo-maxillary,  and  commences 

*  The  sinuses  of  the  base  of  the  skull,  1.  The  ophthalmic  veins.  2.  The  cavernous 
sinus  of  one  side.  3.  The  circular  sinus;  the  figure  occupies  the  position  of  the  pitui- 
tary {fland  in  the  sella  turcica.  4.  The  inferior  petrosal  sinus.  .'>.  Tlic  transverse  or 
anterior  occipital  sinus.  6.  TIic  superior  petrosal  sinus.  7.  Tlic  internal  jugular 
vein.  8.  The  foramen  magnum.  9.  The  occipital  sinuses.  10.  The  torcular  Hero- 
phili.     11,11.  The  lateral  sinuses. 


VEINS  OF  THE  NECK.  335 

at  the  lower  border  of  the  parotid  gland,  in  front  of  the  sterno-mas- 
toid  muscle.  It  descends  the  neck  in  the  direction  of  a  line  drawn 
from  the  angle  of  the  lower  jaw  to  the  middle  of  the  clavicle,  crosses 
the  sterno-mastoid,  and  terminates  near  the  posterior  and  inferior 
attachment  of  that  muscle  in  the  subclavian  vein.  In  its  course 
downwards  it  lies  upon  the  anterior  lamella  of  the  deep  cervical 
fascia,  which  separates  it  from  the  sterno-mastoid  muscle,  and  is 
covered  in  by  the  platysma  myoides  and  superficial  fascia.  At  the 
root  of  the  neck  it  pierces  the  deep  cervical  fascia ;  it  is  accompa- 
nied, for  the  upper  half  of  its  course,  by  the  auricularis  magnus 
nerve.  The  branches  which  it  receives  are  the  occipital  and  pos- 
terior cervical  cutaneous,  and,  near  its  termination,  the  supra  and 
posterior  scapular. 

The  external  jugular  vein  is  very  variable  in  size,  and  is  occa- 
sionally replaced  by  two  veins.  In  the  parotid  gland  it  receives  a 
large  communicating  branch  from  the  internal  jugular  vein. 

The  Anterior  jugular  vein  is  a  trunk  of  variable  size,  which  col- 
lects the  blood  from  the  integument  and  superficial  structures  on  the 
fore  part  of  the  neck.  It  passes  downwards  along  the  anterior  bor- 
der of  the  sterno-mastoid  muscle,  and  opens  into  the  subclavian  vein, 
near  to  the  termination  of  the  external  jugular.  The  two  veins 
communicate  with  each  other,  with  the  external  and  with  the  inter- 
nal jugular  vein. 

The  Internal  jugular  vein,  formed  by  the  convergence  of  the 
lateral  and  inferior  petrosal  sinus,  commences  at  the  foramen  lacerum 
posterius  on  each  side  of  the  base  of  the  skull,  and  descends  the  side 
of  the  neck,  lying,  in  the  first  instance,  to  the  outer  side  of  the  in- 
ternal carotid,  and  then  upon  the  outer  side  of  the  common  carotid 
artery  to  the  root  of  the  neck,  where  it  unites  with  the  subclavian, 
and  constitutes  the  vena  innominata.  At  its  commencement,  the 
internal  jugular  vein  is  posterior  and  external  to  the  internal  carotid 
artery,  and  to  the  eighth  and  ninth  pairs  of  nerves ;  lower  down,  the 
vein  and  artery  are  on  the  same  plane,  the  glosso-pharyngeal  and 
hypoglossal  nerves  passing  forwards  between  them,  the  pneumo- 
gastric  being  between  and  behind  in  the  same  sheath,  and  the  nervus 
accessorius  crossing  obliquely  behind  the  vein. 

The  Branches  which  the  internal  jugular  receives  in  its  course 
are,  the  facial,  the  lingual,  the  inferior  fharyngeal,  the  occipital,  and 
the  superior  and  inferior  thyroid  veins. 

The  Vertebral  vein  descends  by  the  side  of  the  vertebral  artery 
in  the  canal  formed  by  the  foramina  in  the  transverse  processes  of 
the  cervical  vertebrae,  and  terminates  at  the  root  of  the  neck  in  the 
commencement  of  the  vena  innominata.  In  the  lower  part  of  the 
vertebral  canal  it  frequently  divides  into  two  branches,  one  of  which 
advances  forwards,  while  the  other  passes  through  the  foramen  in 
the  transverse  process  of  the  seventh  cervical  vertebra,  before 
opening  into  the  vena  innominata. 

The  Branches  which  it  receives  in  its  course  arc  the  posterior 


336  VEINS  OF  THE  UPPER  EXTREMITY. 

condyloid  vein,  muscular  branches,  the  cervical  meningo-rachidian 
veins,  and,  near  its  termination,  the  superficial  and  deep  cervical 
veins. 

The  Inferior  thyroid  veins,  two,  and  frequently  more  in  number, 
are  situated  on  one  side  of  the  trachea,  and  receive  the  venous 
blood  from  the  thyroid  gland.  They  communicate  with  each  other 
and  with  the  superior  thyroid  veins,  and  form  a  plexus  upon  the 
front  of  the  trachea.  The  risht  vein  terminates  in  the  right  vena 
innominata,  just  at  its  union  with  the  superior  cava,  and  the  left  in 
the  left  vena  innominata. 


VEINS  OF  THE  UPPER  EXTREMITY. 

The  veins  of  the  upper  extremity  are  the  deep  and  superficial. 
The  deep  veins  accompany  the  branches  and  trunks  of  the  arteries, 
and  constitute  their  vence  comites.  The  venae  comites  of  the  radial 
and  ulnar  arteries  are  enclosed  in  the  same  sheath  with  those  ves- 
sels, and  terminate  at  the  bend  of  the  elbow  in  the  brachial  veins. 
The  brachial  venae  comites  are  situated  one  on  each  side  of  the 
artery,  and  open  into  the  axillary  vein ;  the  axillary  becomes  the 
subclavian,  and  the  subclavian  unites  with  the  internal  jugular  to 
form  the  vena  innominata. 

The  Superficial  veins  of  the  fore-arm  are  the — 

Anterior  ulnar  vein, 
Posterior  ulnar  vein, 
Basilic  vein, 
Radial  vein, 
Cephalic  vein, 
Median  vein, 
Median  basihc. 
Median  cephalic, 

The  Anterior  idnar  vein  collects  the  venous  blood  from  the  inner 
border  of  the  hand,  and  from  the  vein  of  the  little-finger,  vena  sal- 
vatella,  and  ascends  the  inner  side  of  the  fore-arm  to  the  bend  of 
the  elbow,  where  it  becomes  the  basilic  vein. 

The  Posterior  ulnar  vein,  irregular  in  size  and  frequently  absent, 
commences  also  upon  the  inner  border  and  posterior  aspect  of  the 
hand,  and,  ascending  the  fore-arm,  terminates  in  front  of  the  inner 
condyle,  in  the  anterior  ulnar  vein. 

The  Basilic  vein  (/SatfiXixog,  royal,  or  principal)  ascends  from  the 
common  ulnar  vein,  formed  by  the  two  preceding,  along  the  inner 
side  of  the  upper  arm,  and  near  its  middle  pierces  the  fascia ;  it 
then  passes  upwards  to  the  axilla,  and  becomes  the  axillary  vein. 

The  Radial  vein  commences  in  the  large  vein  of  the  thumb,  on 
the  outer  and  posterior  aspect  of  the  hand,  and  ascends  along  the 
outer  border  of  the  fore-arm  to  the  bend  of  the  elbow,  where  it 
becomes  the  cephalic  vein. 


CEPHALIC  VEIN AXILLAKY  VEIN. 


337 


Fig.  120.^ 


The  Cephalic  vein  (xs^akri,  the  head)  ascends  along  the  outer  side 
of  the  arm  to  its  upper  third  ;  it  then  enters  the  groove  between  the 
pectorahs  major  and  deltoid  muscles,  where 
it  is  in  relation  with  the  descending  branch 
of  the  thoracico-acromialis  artery,  and  ter- 
minates beneath  the  clavicle  in  the  subcla- 
vian vein.  A  large  communicating  branch 
sometimes  crosses  the  clavicle  between  the 
external  jugular  and  this  vein,  which  gives 
it  the  appearance  of  being  derived  directly 
from  the  head — hence  its  appellation. 

The  Median  vein  is  intermediate  between 
the  anterior  ulnar  and  radial  vein ;  it  collects 
the  blood  from  the  anterior  aspect  of  the 
fore-arm,  communicating  with  the  two  pre- 
ceding. At  the  bend  of  the  elbow  it  receives 
a  branch  from  the  deep  veins,  and  divides 
into  two  branches,  the  median  cephalic  and 
median  basilic. 

The  Median  cephalic  vein,  generally  the 
smaller  of  the  two,  passes  obliquely  outwards, 
in  the  groove  between  the  biceps  and  the 
supinator  longus,  to  join  the  cephalic  vein. 
The  branches  of  the  external  cutaneous 
nerve  pass  behind  it. 

The  Median  basilic  vein  passes  obliquely  inwards,  in  the  groove 
between  the  biceps  and  pronator  radii  teres,  and  terminates  in  the 
basilic  vein.  This  vein  is  crossed  by  one  or  two  filaments  of  the 
internal  cutaneous  nerve,  and  is  separated  from  the  brachial  artery 
by  the  aponeurotic  slip  given  off  by  the  tendon  of  the  biceps. 


AXILLARY  VEIN. 


The  axillary  vein  is  formed  by  the  union  of  the  vense  comites  of 
the  brachial  artery  with  the  basilic  vein.  It  lies  in  front  of  the 
artery,  and  receives  numerous  branches  from  the  collateral  veins 
of  the  branches  of  the  axillary  artery,  and,  at  the  lower  border  of 
the  first  rib,  becomes  the  subclavian  vein. 


*  The  veins  of  the  fore-arm  and  bend  of  the  elbow.  1.  The  radial  vein.  2.  The 
cephalic  vein.  3.  The  anterior  ulnar  vein.  4.  The  posterior  ulnar  vein.  5.  'I'he  trunk 
formed  by  their  union.  6.  The  basilic  vein,  piercing  the  deep  fascia  at  7.  8.  Tlic  median 
vein.  9.  A  communicating  branch  between  the  deep  veins  of  the  fore-arm  and  tlie  upper 
part  of  the  median  vein.  10.  The  median  cephalic  vein.  11.  Tiie  median  basilic.  12.  A 
slight  convexity  of  the  deep  fascia,  formed  l)y  the  brachial  artery.  13.  The  process  of 
fascia,  derived  trom  the  tendon  of  the  biceps,  and  separating  the  median  basilic  vein  from 
the  brachial  artery.  14.  The  external  cutaneous  nerve,  piercing  tlie  deep  fascia,  and 
dividing  into  two  branches,  which  pass  behind  the  median  cephalic  vein.  15.  The  in- 
ternal cutaneous  nerve,  dividing  into  branches,  which  pass  in  front  of  ihe  median 
basilic  vein.  16.  The  intercosto  humeral  cutaneous  nerve.  17.  The  spiral  cutaneous 
jiervCj  a  branch  of  the  musculo-sjiiral. 

43 


338  SUBCLAVIAN  VEIN FEMORAL  VEIN. 


SUBCLAVIAN  VEIN. 

The  subclavian  vein  crosses  over  the  first  rib  and  beneath  the 
clavicle,  and  unites  with  the  internal  jugular  vein  to  form  the  vena 
innominata.  It  lies  at  first  in  front  of  the  subclavian  artery,  and 
then  in  front  of  the  scalenus  anticus,  which  separates  it  from  that 
vessel.  The  phrenic  and  pneumogastric  nerves  pass  between  the 
artery  and  vein.  The  veins  opening  into  the  subclavian  are  the 
cephalic  below  the  clavicle,  and  the  external  and  anterior  jugulars 
above ;  occasionally  some  small  veins  from  the  neighbouring  parts 
also  terminate  in  it. 

VEINS  OF  THE  LOWER  EXTREMITY. 

The  veins  of  the  lower  extremity  are  the  deep  and  superficial. 
The  deep  veins  accompany  the  branches  of  the  arteries  in  pairs,  and 
form  the  venae  comites  of  the  anterior  and  posterior  tibial  and  pero- 
neal arteries.  These  veins  unite  in  the  popliteal  region  to  form  a 
single  vein  of  large  size — the  popliteal — which  successively  becomes 
in  its  course  the  femoral  and  the  external  iliac  vein. 

POPLITEAL  VEIN. 

The  popliteal  vein  ascends  through  the  popliteal  region,  lying, 
in  the  first  instance,  directly  upon  the  artery,  and  then  getting  some- 
what to  its  outer  side.  It  receives  several  muscular  and  articular 
veins,  and  the  external  saphenous  vein.  The  valves  in  this  vein  are 
four  or  five  in  number. 

FEMORAL  VEIN. 

The  femoral  vein,  passing  through  the  opening  in  the  adductor 
magnus  muscle,  ascends  the  thigh  in  the  sheath  of  the  femoral  artery, 
and  entering  the  pelvis  beneath  Poupart's  ligament,  becomes  the 
external  iliac  vein.  In  the  lower  part  of  its  course  it  is  situated  upon 
the  outer  side  of  the  artery;  it  then  becomes  placed  behind  that  ves- 
sel, and,  at  Poupart's  ligament,  lies  to  its  inner  side.  It  receives 
the  muscular  veins,  and  the  profunda,  and,  through  the  saphenous 
opening,  the  internal  saphenous  vein.  The  valves  in  this  vein  are 
four  or  five  in  number. 

The  Profunda  vein  is  formed  by  the  convergence  of  the  numerous 
small  veins  which  accompany  the  branches  of  the  artery;  it  is  a 
vein  of  large  size,  lying  in  front  of  the  profunda  artery,  and  ter- 
minates in  the  femoral  at  about  an  inch  and  a  half  below  Poupart's 
ligament. 

The  Superficial  veins  are  the  external  or  short,  and  the  internal 
or  long  saphenous. 

The  External  saphenous  vein  collects  the  blood  from  the  outer 


SUPERIOR  VENA  CAVA,  WITH  ITS  FORMATIVE  BRANCHES.  339 

side  of  the  foot  and  leg.  It  passes  behind  the  outer  ankle,  ascends 
along  the  posterior  aspect  of  the  leg,  lying  in  the  groove  between 
the  two  bellies  of  the  gastrocnemius  muscle,  and  pierces  the  deep 
fascia  in  the  pophteal  region  to  join  the  popliteal  vein.  It  receives 
several  cutaneous  branches  in  the  popliteal  region  before  passing 
through  the  deep  fascia,  and  is  accompanied  in  its  course  by  the 
external  saphenous  nerve. 

The  Internal  saphenous  vein  commences  upon  the  dorsum  and 
inner  side  of  the  foot.  It  ascends  in  front  of  the  inner  ankle,  and 
along  the  inner  side  of  the  leg;  it  then  passes  behind  the  inner  con- 
dyle of  the  femur,  and  along  the  inner  side  of  the  thigh  to  the  saphe- 
nous opening,  where  it  pierces  the  sheath  of  the  femoral  vessels, 
and  terminates  in  the  femoral  vein,  at  about  one  inch  and  a  half 
below  Poupart's  ligament. 

It  receives  in  its  course  the  cutaneous  veins  of  the  leg  and  thigh, 
and  communicates  freely  with  the  deep  veins.  At  the  saphenous 
opening  it  is  joined  by  the  superficial  epigastric  and  circumflexa  ilii 
veins,  and  by  the  external  pudic.  The  situation  of  this  vein  in  the 
thigh  is  not  unfrequently  occupied  by  two  or  even  three  trunks  of 
nearly  equal  size. 

VEINS  OF  THE  TRUNK. 

The  veins  of  the  trunk  may  be  divided  into  1.  The  superior  vena 
cava,  with  its  formative  branches.  2.  The  inferior  vena  cava,  with 
its  formative  branches.  3.  The  azygos  veins.  4.  The  vertebral 
and  spinal  veins.  5.  The  cardiac  veins.  6.  The  portal  vein.  7. 
The  pulmonary  veins. 

SUPERIOR  VENA  CAVA,  WITH  ITS  FORMATIVE  BRANCHES. 

VencB  InnominatcB. 

The  VencB  innominatcB  are  two  large  trunks,  formed  by  the  union 
of  the  internal  jugular  and  subclavian  vein,  at  each  side  of  the  root 
of  the  neck. 

The  Right  ve7iainjiominata,  about  Q,ninch  and  a  quarter  in  length,  lies 
superficially  and  externally  to  the  arteria  innominata,  and  descends 
almost  vertically,  to  unite  with  its  fellow  of  the  opposite  side  in  the 
formation  of  the  superior  cava.  At  the  junction  of  the  jugular  and 
subclavian  veins  it  receives  from  behind  the  ductus  lymphaticus 
dexter,  and  lower  down  it  has  opening  into  it  the  right  vertebral, 
right  internal  mammary,  and  right  inferior  thyroid  vein. 

The  Left  vena  innominata,  considerably  longer  than  the  right,  ex- 
tends almost  horizontally  across  the  roots  of  the  three  arteries  arising 
from  the  arch  of  the  aorta,  to  the  right  side  of  the  mediastinum, 
where  it  unites  with  the  right  vena  innominata,  to  constitute  the 
superior  cava. 


340 


SUPERIOR  VENA  CAVA. 


Fig.  121.* 


It  is  in  relation  in  front  with  the  left 
sterno-clavicular  articulation  and  the 
first  piece  of  the  sternum.  At  its  com- 
mencement it  receives  the  thoracic 
duct  which  opens  into  it  from  behind, 
and  in  its  course  is  joined  by  the  left 
vertebral,  left  inferior  thyroid,  left  mam- 
mary, and  by  the  superior  intercostal 
vein.  It  also  receives  some  small  veins 
from  the  mediastinum  and  thymus  gland. 
There  are  no  valves  in  the  venae  innomi- 
natas. 

SUPERIOR  VENA  CAVA. 

The  superior  cava  is  a  short  trunk 
about  three  inches  in  length,  formed  by 
the  junction  of  the  two  vense  innominate. 
It  descends  perpendicularly  on  the  right 
side  of  the  mediastinum,  and  entering  the 
pericardium  terminates  in  the  upper  part 
of  the  right  auricle. 

It  is  in  relation  in  front  with  the  tho- 
racic fascia,  which  separates  it  from  the 
thymus  gland,  and  with  the  pericardium; 
behind  with  the  right  pulmonary  artery, 
and  the  right  superior  pulmonary  vein ; 
internally  with  the  ascending  aorta  ;  ex- 
ternally with  the  right  phrenic  nerve,  and 
right  lung.  Immediately  before  entering 
the  pericardium  it  receives  the  vena 
azygos  major. 


INFERIOR  VENA  CAVA,  WITH  ITS  FORMATIVE  BRANCHES. 

Iliac  Veins. 

The  External  iliac  vein  lies  to  the  inner  side  of  the  corresponding 
artery  at  the  os  pubis;  but  gradually  gets  behind  it  as  it  passes 

*  TJie  veins  of  tlir;  trunk  and  neck.  1.  The  superior  vena  cava.  2.  The  left  vena 
innominata.  3.  Tlie  right  vena  innominata.  4.  Tlie  right  subclavian  vein.  5.  The 
internal  jugular  vein.  6.  Tiic  external  jugular.  7.  The  anterior  jugular.  8.  The 
inferior  vena  cava.  9.  The  external  iliac  vein.  10.  The  internal  iliac  vein.  11.  The 
common  iliac  veins;  the  small  vein  betw^ecn  these  is  the  vena  sacra  media.  12,  12. 
Lumbar  veins.  1.'3.  The  right  spermatic  vein.  14.  The  left  spermatic,  opening  into 
the  left  renal  vein.  l.'j.  The  right  renal  vein.  1  (I.  The  trunk  of  the  hepatic  veins. 
17.  The  greater  vena  azygos,  commencing  inferiorly  in  tlie  lumbar  veins.  18.  The 
lesser  vena  azygos,  also  commencing  in  the  lumbar  veins.  19.  A  branch  of  communi- 
cation with  the  left  renal  vein.  20.  The  termination  of  the  lesser  in  the  greater  vena 
azygos.  21.  The  superior  intercostal  vein;  communicating  inferiorly  with  the  lesser 
vena  azygos,  and  terminating  superiorly  in  the  loft  vena  innominata. 


INFERIOR  VENA  CAVA.  341 

upwards  along  the  brim  of  the  pelvis,  and  terminates  opposite  the 
sacro-iliac  symphysis  by  uniting  with  the  internal  iliac,  to  form  the 
common  iliac  vein.  Immediately  above  Poupart's  ligament  it 
receives  the  epigastric  and  the  circumflexa  ihi  veins ;  it  has  no 
valves. 

The  Internal  iliac  vein  is  formed  by  vessels  which  correspond 
with  the  branches  of  the  internal  iliac  artery;  it  receives  the  return- 
ing blood  from  the  gluteal,  ischiatic,  internal  pudic,  and  obturator 
veins,  externally  to  the  pelvis ;  and  from  the  vesical  and  uterine 
plexuses  within  the  pelvis.  The  vein  lies  to  the  inner  side  of  the 
internal  iliac  artery,  and  terminates  by  uniting  with  the  external 
ihac  vein,  to  form  the  common  ihac. 

The  Vesical  and  -prostatic  plexus  is  an  important  plexus  of  veins 
which  surrounds  the  neck  and  base  of  the  bladder  and  prostate 
gland,  and  receives  its  blood  from  the  great  dorsal  vein  of  the  penis, 
and  from  the  veins  of  the  external  organs  of  generation.  It  is 
retained  in  connexion  with  the  sides  of  the  bladder  by  a  reflection 
of  the  pelvic  fascia. 

The  Uterine  plexus  is  situated  around  the  vagina,  and  upon  the 
sides  of  the  uterus,  between  the  two  layers  of  the  broad  ligaments. 
The  veins  forming  the  vesical  and  uterine  plexus  are  very  subject 
to  the  production  of  phlebolitis. 

The  Common  iliac  veins  are  formed  by  the  union  of  the  external 
and  internal  iliac  vein  on  each  side  of  the  pelvis.  The  right  conmion 
iliac,  shorter  than  the  left,  ascends  obliquely  behind  the  correspond- 
ing artery  ;  and  upon  the  intervertebral  substance  between  the  fourth 
and  fifth  lumbar  vertebra3,  unites  with  the  vein  of  the  opposite  side, 
to  form  the  inferior  cava.  The  left  common  iliac,  longer  and  more 
oblique  than  the  right,  ascends  behind,  and  a  little  internally  to  the 
corresponding  artery,  and  passes  beneath  the  right  common  iliac 
artery,  near  to  its  origin,  to  unite  with  the  right  vein  in  the  formation 
of  the  inferior  vena  cava.  The  right  common  iliac  vein  has  no 
branch  opening  into  it;  the  left  receives  the  vena  sacra  media. 
These  veins  have  no  valves. 

INrERIOR  VENA  CAVA. 

The  inferior  vena  cava  is  formed  by  the  union  of  the  two  common 
iliac  veins,  upon  the  intervertebral  substance  between  the  fourtli 
and  fifth  lumbar  vertebra.  It  ascends  along  the  front  of  the  vertebral 
column,  on  the  right  side  of  the  abdominal  aorta,  and  passing  through 
the  fissure  in  the  posterior  border  of  the  hver  and  the  quadrilateral 
opening  in  the  tendinous  centre  of  the  diaphragm,  terminates  in  the 
inferior  and  posterior  part  of  the  right  auricle.  There  are  no  valves 
in  this  vein. 

It  is  in  relation  from  below  upwards,  in  front  with  the  mesentery, 
transverse  duodenum,  portal  vein,  pancreas,  and  liver  which  nearly 
and  sometimes  completely  surrounds  it;  behind  it  rests  upon  the 
vertebral  column  and  right  crus  of  the  diaphragm,  from  which  it  is 


342  BRANCHES  OF  INFERIOR  CAVA. 

separated  by  the  right  renal  and  lumbar  arteries ;  to  the  right  it  has 
the  peritoneum  and  sympathetic  nerve ;  and  to  the  left  the  aorta. 

The  Branches  which  the  inferior  cava  receives  in  its  course,  are 
the— 

Lumbar. 

Right  spermatic, 

Renal, 

Supra-renal, 

Phrenic, 

Hepatic. 

The  Lumhar  veins,  three  or  four  in  number  on  each  side,  collect 
the  venous  blood  from  the  muscles  and  integument  of  the  loins,  and 
from  the  spinal  veins ;  the  left  are  longer  than  the  right  from  the 
position  of  the  vena  cava. 

The  Right  spermatic  vein  is  formed  by  the  two  veins  which  re- 
turn the  blood  from  the  venous  plexus,  situated  in  the  spermatic 
cord.  These  veins  follow  the  course  of  the  spermatic  artery,  and 
unite  to  form  the  single  trunk  which  opens  into  the  inferior  vena 
cava.     The  left  s-pei-matic  vein  terminates  in  the  left  renal  vein. 

The  Ovarian  veins  represent  the  spei'matic  veins  of  the  male,  and 
collect  the  venous  blood  from  the  ovaries,  round  ligaments,  and 
Fallopian  tubes,  and  communicate  with  the  uterine  sinuses.  They 
terminate  as  in  the  male. 

The  Renal  or  emulgent  veins  return  the  blood  from  the  kidneys ; 
their  branches  are  situated  in  front  of  the  divisions  of  the  renal 
arteries,  and  the  left  opens  into  the  vena  cava  somewhat  higher  than 
the  right.  The  left  is  longer  than  the  right  in  consequence  of  the 
position  of  the  vena  cava,  and  crosses  the  aorta  immediately  below 
the  origin  of  the  superior  mesenteric  artery.  It  receives  the  left 
spermatic  vein,  which  terminates  in  it  at  right  angles :  hence  the 
more  frequent  occurrence  of  varicocele  on  the  left  than  on  the  right 
side. 

The  Supra-renal  veins  terminate  partly  in  the  renal  veins,  and 
partly  in  the  inferior  vena  cava. 

The  Phrenic  veins  return  the  blood  from  the  ramifications  of  the 
phrenic  arteries ;  they  open  into  the  inferior  cava. 

The  Hepatic  veins  form  two  principal  trunks  and  numerous  smaller 
veins  which  open  into  the  inferior  cava,  while  that  vessel  is  situated 
in  the  posterior  border  of  the  liver.  The  hepatic  veins  commence 
in  the  liver  by  minute  venules,  the  intralobular  veins  in  the  centre  of 
each  lobule ;  these  pour  their  blood  into  larger  vessels,  the  sublobular 
veins ;  and  the  sublobular  veins  constitute  by  their  convergence  and 
union,  the  hepatic  trunks,  which  terminate  in  the  inferior  vena  cava. 

AZYGOS  VEINS. 

The  azygos  veins  form  a  system  of  communication  between  the 
superior  and  inferior  vena  cava,  and  serve  to  return  the  blood  from 


VERTEBRAL  AND  SPINAL  VEINS.  343 

that  part  of  the  trunk  in  which  those  vessels  are  deficient,  on  account 
of  their  connexion  with  the  heart.  This  system  consists  of  three 
vessels,  the — 

Vena  azygos  major, 
Vena  azygos  minor, 
Superior  intercostal  vein. 

The  Vena  azygos  major  commences  in  the  lumbar  region  by  a 
communication  with  the  lumbar  veins ;  sometimes  it  is  joined  by  a 
branch  directly  from  the  inferior  vena  cava,  or  by  one  from  the 
renal  vein.  It  passes  through  the  aortic  opening  in  the  diaphragm, 
and  ascends  upon  the  right  side  of  the  vertebral  column  to  the  third 
dorsal  vertebra,  where  it  arches  forwards  over  the  right  bronchus, 
and  terminates  in  the  superior  cava.  It  receives  all  the  intercostal 
veins  of  the  right  side,  the  vena  azygos  minor,  and  the  bronchial 
veins. 

The  Vena  azygos  minor  commences  in  the  lumbar  region,  on  the 
left  side,  by  a  communication  with  the  lumbar  or  renal  veins.  It 
passes  beneath  the  border  of  the  diaphragm,  and  ascending  upon 
the  left  side  of  the  vertebral  column  crosses  the  fifth  or  sixth  dorsal 
vertebra  to  open  into  the  vena  azygos  major.  It  receives  the  six 
or  seven  lower  intercostal  veins  of  the  left  side.  The  azygos  veins 
have  no  valves. 

The  Superior  intercostal  vein  is  the  trunk  formed  by  the  union  of 
the  five  or  six  upper  intercostal  veins  of  the  left  side.  It  communi- 
cates below  with  the  vena  azygos  minor,  and  ascends  to  terminate  in 
the  left  vena  innominata. 

VERTEBRAL  AND  SPINAL  VEINS. 

The  numerous  venus  plexuses  of  the  vertebral  column  and  spinal 
cord  may  be  arranged  into  three  groups : — 

Dorsi-spinal, 

Meningo-rachidian, 

MeduUi-spinal. 

The  Dorsi-spinal  veins  form  a  plexus  around  the  spinous,  trans- 
verse and  articular  processes  and  arches  of  the  vertebrag.  They 
receive  the  returning  blood  from  the  dorsal  muscles  and  surrounding 
structures,  and  transmit  it,  in  part  to  the  meningo-rachidian,  and  in 
part  to  the  vertebral,  intercostal,  lumbar,  and  sacral  veins. 

The  Meningo-rachidian  veins  are  situated  between  the  theca  ver- 
tebralis  and  the  vertebra.  They  communicate  freely  with  each 
other  by  means  of  a  complicated  plexus.  In  front  they  form  two 
longitudinal  trunks,  which  extend  the  whole  length  of  the  column  on 
each  side  of  the  posterior  common  ligament,  and  are  joined  on  the 
body  of  each  vertebra  by  transverse  trunks,  which  pass  beneath  the 
ligament,  and  receive  the  large  vertebral  veins  from  the  interior  of 
each  vertebra.     They  pour  their  blood  into  the  vertebral  veins  in 


344  PORTAIi  SYSTEM. 

the  neck,  into  the  intercostal  veins  in  the  thorax,  and  into  the  lumbar 
and  sacral  veins  in  the  loins  and  pelvis,  by  means  of  communicating 
trunks,  which  escape  at  the  intervertebral  foramina. 

The  Medulli-spinul  veins  are  situated  between  the  pia  mater  and 
arachnoid ;  they  communicate  freely  with  each  other,  and  form 
plexuses,  and  send  branches  through  the  intervertebral  foramina  with 
each  of  the  spinal  nerves,  to  join  the  veins  of  the  trunk. 

CARDIAC  VEINS. 

The  veins  returning  the  blood  from  the  substance  of  the  heart, 
are  the — 

Great  cardiac  vein. 
Posterior  cardiac  veins. 
Anterior  cardiac  veins, 
Venae  Thebesii. 

The  Great  cardiac  vein  (coronary)  commences  at  the  apex  of  the 
heart,  and  ascends  along  the  anterior  ventricular  groove  to  the  base 
of  the  ventricles ;  it  then  curves  around  the  left  auriculo-ventricular 
groove  to  the  posterior  part  of  the  heart,  where  it  terminates  in  the 
right  auricle.  It  receives  in  its  course  the  left  cardiac  veins  from 
the  left  auricle  and  ventricle,  and  the  posterior  cardiac  veins  from 
the  posterior  ventricular  groove. 

The  Posterior  cardiac  vein,  frequently  two  in  number,  commences 
also  at  the  apex  of  the  heart,  and  ascends  along  the  posterior  ven- 
tricular groove,  to  teminate  in  the  great  cardiac  vein.  It  receives 
the  veins  from  the  posterior  aspect  of  the  two  ventricles. 

The  Anterior  cardiac  veins  collect  the  blood  from  the  anterior  sur- 
face of  the  right  ventricle ;  one  larger  than  the  rest  runs  along  the 
right  border  of  the  heart  and  joins  the  trunk  formed  by  these  veins, 
which  curves  around  the  right  auriculo-ventricular  groove,  to  termi- 
nate in  the  great  cardiac  vein  near  to  its  entrance  into  the  right 
auricle. 

The  Fence.  Thebesii  are  numerous  minute  venules  which  convey 
the  venous  blood  directly  from  the  substance  of  the  heart  into  its 
four  cavities.     Their  existence  is  denied  by  some  anatomists. 

PORTAL  SYSTEM. 

The  portal  system  is  composed  of  four  large  veins  which  return 
the  blood  from  the  chylopoietic  viscera ;  they  are  the — 

Inferior  mesenteric  vein, 
Superior  mesenteric  vein, 
Splenic  vein. 
Gastric  veins. 

The  Inferior  mesenteric  vein  receives  its  blood  from  the  rectum  by 
means  of  the  ha-jmorrhoidal  veins,  and  from  the  sigmoid  flexure  and 
descending  colon,  and  ascends  beneath  the  transverse  duodenum  and 


SPLENIC  VEIN. 


345 


pancreas,  to  terminate  in  the  splenic  vein.  Its  haemorrhoidal  branches 
inosculate  with  the  branches  of  the  internal  ihac  vein,  and  thus 
establish  a  communication  between  the  portal  and  general  venous 
system. 

The  Swperior  mesenteric  vein  is  formed  by  branches  which  col- 
lect the  venous  blood  from  the  capillaries  of  the  superior  mesenteric 
artery ;  they  constitute  by  their  junction  a  large  trunk  which 
ascends  by  the  side  of  the  corresponding  artery,  crosses  the  trans- 
verse duodenum,  and  unites  behind  the  pancreas  with  the  splenic  in 
the  formation  of  the  portal  vein. 

Fig.  122.* 


The  Splenic  vein  commences  in  the  structure  of  the  spleen,  and 
quits  that  organ  by  several  lai-ge  veins  ;  it  is  larger  than  the  splenic 
artery,  and  perfectly  straight  in  its  course.  It  passes  horizontally 
inwards  behind  the  pancreas,  and  terminates  near  its  greater  end  by 
uniting  with  the  superior  mesenteric  and  forming  the  portal  vein.    It 


*  The  portal  vein.  1.  The  inferior  mesenteric  vein;  it  is  traced  by  means  of  dotted 
lines  behind  the  pancreas  (2)  to  terminate  in  the  splenic  vein  (3).  4.  TJie  spleen.  5. 
Gastric  veins,  opening  into  the  splenic  vein.  6.  The  superior  mesenteric  vein.  7.  The 
descending-  portion  of  the  duodenum.  8.  Its  transverse  portion,  which  is  crossed  by 
the  superior  mesenteric  vein  and  by  a  part  of  the  trunk  of  the  superior  mesenteric 
artery.  9.  The  portal  vein.  10.  The  hepatic  artery.  11.  The  ductus  communis 
choledochus.  12.  The  divisions  of  the  duct  and  vessels  at  the  transverse  fissure  of  the 
liver.     13.  The  cystic  duct  leading  to  the  gall-bladder. 

44 


346  PULMONARY  VEINS. 

receives  in  its  course  the  gastric  and  pancreatic  veins,  and  near  its 
termination  the  inferior  mesenteric  vein. 

The  Gastric  veins  correspond  with  the  gastric,  gastro-epiploic, 
and  vasa  brevia  arteries,  and  terminate  in  the  splenic  vein. 

The  Vexa  PoRTiE,  formed  by  the  union  of  the  splenic  and  supe- 
rior mesenteric  vein  behind  the  pancreas,  ascends  through  the  right 
border  of  the  lesser  omentum  to  the  transverse  fissure  of  the  hver, 
where  it  divides  into  two  branches,  one  for  each  lateral  lobe.  In 
the  right  border  of  the  lesser  omentum  it  is  situated  behind  and  be- 
tween the  hepatic  artery  and  ductus  communis  choledochus,  and  is 
surrounded  by  the  hepatic  plexus  of  nerves  and  lymphatics.  At  the 
transverse  fissure  each  primary  branch  divides  into  numerous 
secondary  branches  which  ramify  through  the  portal  canals,  and 
give  off  vaginal  and  interlobular  veins,  which  terminate  in  the  lobular 
venous  plexus  of  the  lobules  of  the  liver.  The  portal  vein  within 
the  liver  receives  the  venous  blood  from  the  capillaries  of  the  hepatic 
artery. 

PULMONARY  VEINS. 

The  pulmonary  veins,  four  in  number,  return  the  arterial  blood 
from  the  lungs  to  the  left  auricle  of  the  heart ;  they  differ  from  the 
veins  in  general,  in  the  area  of  their  cylinders,  being  very  little  larger 
than  the  corresponding  arteries,  and  in  accompanying  singly  each 
branch  of  the  pulmonary  artery.  They  commence  in  the  capilla- 
ries upon  the  parietes  of  the  bronchial  cells,  and  unite  to  form  a 
single  trunk  for  each  lobe.  The  vein  of  the  middle  lobe  of  the  right 
lung  unites  with  the  superior  vein  so  as  to  form  the  two  trunks 
which  open  into  the  left  auricle.  Sometimes  they  remain  separate, 
and  then  there  are  three  pulmonary  veins  on  the  right  side.  The 
right  pulmonary  veins  pass  behind  the  superior  vena  cava  to  the 
left  auricle,  and  the  left  behind  the  pulmonary  artery ;  they  both 
pierce  the  pericardium.  Within  the  lung  the  branches  of  the  pul- 
monary veins  are  behind  the  bronchial  tubes,  and  those  of  the  pul- 
monary artery  in  front ;  but  at  the  root  of  the  lungs  the  veins  are  in 
front,  next  the  arteries,  and  then  the  bronchi.  There  are  no  valves 
in  the  pulmonary  veins. 


CHAPTER   VII 


ON  THE  LYMPHATICS. 


The  lymphatic  vessels,  or  absorbents,  have  received  their  double 
appellation  from  certain  phenomena  which  they  present ;  the  former 
name  is  derivable  from  the  peculiar  limpid  fluid  (lympha,  water,) 
which  they  convey ;  and  the  latter,  from  their  supposed  property 
of  absorbing  foreign  substances  into  the  system.  They  are  minute 
and  delicate  vessels,  having  a  knotted  appearance,  and  are  distri- 
buted through  every  part  of  the  body.  Their  office  is  to  collect 
the  products  of  digestion,  and  the  detrita  of  nutrition,  and  to  convey 
them  into  the  venous  circulation  near  to  the  heart. 

Lymphatic  vessels  commence  in  a  delicate  network  which  is  dis- 
tributed upon  the  cutaneous  surface  of  the  body,  upon  the  various 
surfaces  of  organs  and  throughout  their  internal  structure  ;  and 
from  this  network  the  lymphatic  vessels  proceed,  nearly  in  straight 
lines,  in  a  direction  towards  the  root  of  the  neck.  In  their  course 
they  are  intercepted  by  numerous  small  oval  or  rounded  bodies — 
lymphatic  glands — in  which  the  entering  or  inferent  vessels  ramify 
to  an  extreme  minuteness,  and  from  which  proceed  the  escaping  or 
efferent  vessels  somewhat  larger  in  size  and  fewer  in  number,  to  be 
again  and  again  subdivided  into  other  glands,  and  each  time  to  be 
a  little  more  increased  in  size. 

Lymphatic  vessels  admit  of  a  threefold  division  into  superficial, 
deep,  and  lacteals.  The  superficial  lymphatic  vessels,  upon  the  sur- 
face of  the  body,  follow  the  course  of  the  veins,  and  pierce  the 
deep  fascia  in  convenient  situations,  to  join  the  deep  lymphatics. 
Upon  the  surface  of  organs  they  converge  to  the  nearest  lymphatic 
trunks. 

The  Superficial  lymphatic  glands  are  placed  in  the  most  protected 
situations  of  the  superficial  fascia,  as  in  the  hollow  of  the  ham  and 
groin  in  the  lower  extremity,  and  upon  the  inner  side  of  the  arm  in 
the  upper  extremity.  The  deep  lymphatics  accompany  the  deeper 
veins  ;  those  from  the  lower  parts  of  the  body  converging  to  the 
numerous  glands  seated  around  the  iliac  veins  and  inferior  vena 
cava,  and  terminating  in  a  large  trunk  situated  upon  the  vertebral 
column — the  thoracic  duct.  From  the  upper  part  of  the  trunk  on 
the  left  side,  and  from  the  left  side  of  the  head  and  neck,  they  also 
proceed  to  the  thoracic  duct.  Those  on  the  right  side  of  the  head, 
and  neck,  right  upper  extremity,  and  right  side  of  the  thorax,  form 
a  distinct  duct  which  terminates  at  the  point  of  junction  of  the  sub- 


348  XYMPHATICS  OF  THE  HEAD  AND   NECK. 

clavian  with  the  internal  jugular  vein  on  the  right  side  of  the  root 
of  the  neck. 

The  lacteah  are  the  lymphatics  of  the  small  intestines ;  they 
have  i-eceived  their  distinctive  appellation  from  conveying  the  milk- 
hke  product  of  digestion — the  chyle — to  the  great  centre  of  the  lym- 
phatic system — the  thoracic  duct.  They  are  situated  in  the  mesen- 
tery, and  pass  through  the  numerous  mesenteric  glands  in  their 
course. 

The  communications  between  lymphatic  vessels  are  less  frequent 
than  those  of  arteries  or  veins;  their  anastomoses  take  place  by  means 
of  branches  of  equal  calibre  that  unite  at  acute  angles,  and  con- 
stitute a  combined  trunk  which  is  scarcely  larger  than  either  of  the 
single  branches  by  which  it  is  formed. 

Lymphatic  vessels  are  composed  of  two  coats ;  an  external  or 
cellular,  and  an  internal  or  serous. 

The  External  coat  resembles  the  external  tunic  of  veins  and  arte- 
ries, bat  is  extremely  thin  and  dense.  The  Internal  coat  is  continuous 
with  the  internal  hning  of  the  veins;  and,  like  that  membrane,  is 
most  probably  provided  with  an  ephhelium.  At  short  intervals  this 
coat  forms  semilunar  folds  which  are  disposed  in  pairs  in  the 
cylinder  of  the  vessel  and  constitute  the  valves.  It  is  to  these  valves, 
which  are  extremely  numerous  in  lymphatics,  that  their  peculiar 
knotted  appearance  is  due,  when  filled  with  injection. 

The  lymphatic  glands  are  small  oval  and  somewhat  flattened  or 
rounded  bodies,  composed  of  a  plexus  of  minute  lymphatic  vessels, 
associated  with  a  plexus  of  blood-vessels,  and  enclosed  in  a  thin 
cellular  capsule.  The  larger  glands  have  a  lobed  or  cellular 
appearance.  The  lymphatic  vessels  and  glands  are  supplied  with 
arteries,  veins,  and  nerves,  like  other  structures. 

I  shall  describe  the  lymphatic  vessels  and  glands  according  to  the 
arrangement  adopted  for  the  veins,  commencing  with  those  of  the 
head  and  neck,  and  proceeding  next  to  those  of  the  upper  extremity, 
lower  extremity,  and  trunk. 

LYMPHATICS  OF  THE  HEAD  AND  NECK. 

The  Superficial  lymphatic  glands  of  the  head  and  face  are  small 
and  few  in  number ;  they  are  the  occipital,  which  are  situated  near 
the  origin  of  the  occipito-frontalis  muscle;  posterior  auricular, 
behind  the  ear;  parotid,  in  the  parotid  gland;  zygomatic,  in  the 
zygomatic  fossa;  buccal,  upon  the  buccinator  muscle;  and  sub- 
maxillary,  beneath  the  margin  of  the  lower  jaw.  There  are  no 
deep  lymphatic  glands  within  the  cranium. 

The  Sit-perficial  cervical  lymphatic  glands  are  few  in  number ; 
they  are  situated  in  the  course  of  the  external  jugular  vein,  between 
the  sterno-mastoid  and  trapezius  muscles,  at  the  root  of  the  neck 
and  about  the  larynx. 

The  Deep  cervical  glands  are  very  numerous  and  of  large  size  ; 
they  are  situated  around  the  internal  jugular  vein  and  sheath  of  the 


LYMPHATICS  OF  THE  UPPER  EXTREMITY.  349 

arteries,  by  the  side  of  the  pharnyx,  oesophagus,  and  trachea,  and 
extend  from  the  base  of  the  skull  to  the  root  of  the  neck,  where 
they  are  in  communication  with  the  lymphatic  vessels  and  glands 
of  the  thorax. 

The  Swperjicial  lymphatic  vessels  of  the  head  and  face  are  disposed 
in  three  groups;  occipital,  which  take  the  course  of  the  occipital 
vein  to  the  occipital  and  deep  cervical  glands;  temporal,  which  fol- 
low the  branches  of  the  temporal  vein  to  the  parotid  and  deep  cer- 
vical glands;  and  frtc/aZ,  which  accompany  the  facial  vein  to  the 
submaxillary  lymphatic  glands. 

The  Deep  lymphatic  vessels  of  the  head  are  the  meningeal  and 
cerebral;  the  former  are  situated  in  connexion  with  the  meningeal 
veins,  and  escape  through  foramina  at  the  base  of  the  skull,  to  join 
the  deep  cervical  glands.  The  cerebral  lymphatics,  according  to 
Fohmann,  are  situated  upon  the  surface  of  the  pia  mater.  They 
pass  most  probably  through  the  foramina  at  the  base  of  the  skull,  to 
terminate  in  the  deep  cervical  glands. 

The  Deep  lymphatic  vessels  of  the  face  proceed  from  the  nasal 
fossae,  mouth,  and  pharynx,  and  terminate  in  the  submaxillary  and 
deep  cervical  glands. 

The  Supeificial  and  deep  cervical  lymphatic  vessels  accompany  the 
jugular  veins,  passing  from  gland  to  gland,  and  at  the  root  of  the 
neck  communicate  with  the  thoracic  lymphatic  vessels,  and  termi- 
nate, on  the  right  side,  in  the  ductus  lymphaticus  dexter,  and,  on  the 
left,  in  the  thoracic  duct,  near  to  its  termination. 

LYMPHATICS  OF  THE  UPPER  EXTREMITY. 

The  Superficial  lymphatic  glands  of  the  arm  are  not  more  than 
four  or  five  in  number,  and  of  very  small  size.  One  or  two  are 
situated  near  the  median  basilic,  and  cephalic  veins,  at  the  bend  of 
the  elbow;  and  one  or  two  near  to  the  basilic  vein,  on  the  inner  side 
of  the  upper  arm,  immediately  above  the  elbow. 

The  Deep  glands  in  the  fore-arm  are  excessively  small  and  infre- 
quent; two  or  three  may  generally  be  found  in  the  course  of  the 
radial  and  ulnar  vessels.  In  the  upper  arm  there  is  a  chain  of 
small  glands,  accompanying  the  brachial  artery. 

The  Jlxillary  glands  are  numerous  and  of  large  size.  Some  are 
closely  adherent  to  the  vessels,  others  are  dispersed  in  the  loose  cel- 
lular tissue  of  the  axilla,  and  a  small  chain  may  be  observed  extend- 
ing along  the  lower  border  of  the  pectoralis  major  to  the  mammary 
gland.  Two  or  three  subclavian  glands  are  situated  beneath  the 
clavicle,  and  serve  as  the  medium  of  communication  betvv^een  the 
axillary  and  deep  cervical  lymphatic  glands. 

The  Superficial  lymphatic  vessels  of  the  upper  extremity  commence 
at  the  extremities  of  the  fingers,  and  pass  along  the  borders  of  the 
fingers  to  the  dorsum  of  the  hand;  they  next  ascend  the  fore-arm, 
some  on  its  posterior  and  some  on  its  anterior  aspect,  observing  par- 
ticularly the  direction  of  the  veins.     At  the  bend  of  the  elbow  they 


350  LYMPHATICS  OF  THE  LOWER  EXTREMITY. 

converge,  to  form  two  groups  which  accompany  the  basiUc  and 
cephaUc  veins.  The  lymphatics  of  the  basihc  group  communicate 
with  the  glands  situated  immediately  above  the  elbow,  and  ascend 
to  join  tlie  axillary  gland.  Those  of  the  cephaUc  group  for  the 
most  part  cross  the  upper  part  of  the  biceps  muscle,  and  also  enter 
the  axillary  glands,  while  two  or  three  are  continued  onwards  along 
the  cephalic  vein,  in  the  interspace  between  the  pectoralis  major  and 
deltoid  muscle,  to  communicate  with  the  subclavian  glands. 

The  Deep  lymphatics  accompany  the  vessels  of  the  upper  extre- 
mity, and  communicate  occasionally  with  the  superficial  lymphatics. 
They  enter  the  axillary  and  subclavian  glands,  and  at  the  root  of 
the  neck  terminate  on  the  left  side  in  the  thoracic  duct,  and  on  the 
right  side  in  the  ductus  lymphaticus  dexter. 

LYMPHATICS  OF  THE  LOWER  EXTREMITY. 

The  Superficial  lymphatic  glands  of  the  lower  extremity  are  those 
of  the  groin,  the  inguinal,  and  one  or  two  situated  in  the  superficial 
fascia  of  the  posterior  aspect  of  the  thigh,  just  above  the  popliteal 
region. 

The  Inguinal  glands  are  divisible  into  two  groups,  a  superior 
group  of  small  size,  situated  along  the  course  of  Poupart's  ligament, 
and  receiving  the  lymphatic  vessels  from  the  parietes  of  the  abdo- 
men and  genital  organs ;  and  an  inferior  group  of  larger  glands 
clustered  around  the  internal  saphenous  vein  near  to  its  termination, 
and  receiving  the  superficial  lymphatic  vessels  from  the  lower 
extremity. 

The  Deep  lymphatic  glands  are  the  anterior  tibial,  popliteal,  deep 
inguinal,  gluteal,  and  ischiatic. 

The  Anterior  tibial  is  generally  a  single  gland,  placed  on  the  inter- 
osseous membrane,  by  the  side  of  the  anterior  tibial  artery  in  the 
upper  part  of  its  course. 

The  Popliteal  glands,  four  or  five  in  number,  are  embedded  in  the 
loose  cellular  tissue  and  fat  of  the  popliteal  space. 

The  Deep  inguinal  glands,  less  numerous  and  smaller  than  the 
superficial,  are  situated  near  the  femoral  vessels  in  the  groin,  beneath 
the  fascia  lata. 

The  Gluteal  and  ischiatic  glands  are  placed  above  and  below  the 
pyriformis  muscle  at  the  great  ischiatic  foramen. 

The  Superficial  lymphatic  vessels  are  divisible  into  two  groups, 
internal  and  external ;  the  internal  and  principal  group  commencing 
on  the  dorsum  and  inner  side  of  the  foot,  ascend  the  leg  by  the  side 
of  the  internal  saphenous  vein,  and  passing  behind  the  inner  condyle 
of  the  femur,  follow  the  direction  of  that  vein  to  the  groin,  where 
they  join  the  saphenous  group  of  superficial  inguinal  glands.  The 
greater  part  of  the  efferent  vessels  from  these  glands  pierce  the 
cribriform  fascia  of  the  saphenous  opening  and  the  sheath  of  the 
femoral  vessels,  to  join  the  lymphatic  gland  situated  in  the  femoral 
ring,  which  serves  to  establish  a  communication  between  the  lym- 


LYMPHATICS  OF  THE  TRUNK.  351 

phatics  of  the  lower  extremity  and  those  of  the  trunk.  The  other 
efferent  vessels  pierce  the  fascia  lata  to  join  the  deep  glands.  The 
vessels  which  pass  upwards  from  the  outer  side  of  the  dorsum  of  the 
foot,  ascend  upon  the  outer  side  of  the  leg,  and  curve  inwards  just 
below  the  knee,  to  unite  with  the  lymphatics  of  the  inner  side  of  the 
thigh.  The  external grouj)  consists  of  a  few  lymphatic  vessels  which 
commence  upon  the  outer  side  of  the  foot  and  posterior  part  of  the 
ankle,  and  accompany  the  external  saphenous  vein  to  the  popliteal 
region,  where  they  enter  the  popliteal  glands. 

The  Dee])  lymphatic  vessels  accompany  the  deep  veins,  and  com- 
municate with  the  various  glands  in  their  course.  After  joining  the 
deep  inguinal  glands  they  pass  beneath  Poupart's  ligament,  to  com- 
municate with  the  numerous  glands  situated  around  the  iliac  vessels. 
The  deep  lymphatics  of  the  gluteal  region  follow  the  course  of  the 
branches  of  the  gluteal  and  ischiatic  arteries.  The  former  join  the 
glands  situated  upon  the  upper  border  of  the  pyriformis  muscle,  and 
the  latter  after  communicating  with  the  lymphatics  of  the  thigh, 
enter  the  ischiatic  glands. 

LYMPHATICS  OF  THE  TRUNK. 

The  lymphatics  of  the  trunk  may  be  arranged  under  three  heads, 
superficial,  deep,  and  visceral. 

The  Superficial  lymphatic  vessels  of  the  upper  half  of  the  trunk 
pass  upwards  and  outwards  on  each  side,  and  converge,  some  to  the 
axillary  glands,  and  others  to  the  glands  at  the  root  of  the  neck. 
The  lymphatics  from  the  mammary  glands  follow  the  lower  border 
of  the  pectoralis  major,  communicating  by  means  of  a  chain  of 
lymphatic  glands,  with  the  axillary  glands.  The  superficial  lymph- 
atic vessels  of  the  lower  half  of  the  trunk,  of  the  gluteal  region, 
perineum,  and  external  organs  of  generation,  converge  to  the  supe- 
rior group  of  superficial  inguinal  glands.  Some  small  glands  are 
situated  on  each  side  of  the  dorsal  vein  of  the  penis,  near  to  the 
suspensory  ligament ;  from  these,  as  from  the  superficial  lymphatics, 
the  efferent  vessels  pass  into  the  superior  group  of  superficial  inguinal 
glands. 

The  Deep  lymphatic  glands  of  the  thorax  are  the  intercostal,  in- 
ternal mammary,  anterior  mediastinal,  and  posterior  mediastinal. 

The  Intercostal  glands  are  of  small  size,  and  are  situated  on  each 
side  of  the  vertebral  column,  near  to  the  articulations  of  the  heads 
of  the  ribs,  and  in  the  course  of  the  intercostal  arteries. 

The  Internal  mammary  glands,  also  very  small,  are  placed  in  the 
intercostal  spaces,  by  the  side  of  the  internal  mammary  arteries. 

The  Anterior  mediastinal  glands  occupy  the  loose  cellular  tissue 
of  the  anterior  mediastinum,  resting  some  on  the  diaphragm,  but  the 
greater  number  upon  the  large  vessels  at  the  root  of  the  heart. 

The  Posterior  mediastinal  glands  are  situated  along  the  course  of 
the  aorta  and  oesophagus  in  the  posterior  mediastinum,  and  com- 


352  LYMPHATICS  OF  THE  VISCERA. 

municate  above  with  the  deep  cervical  glands,  on  each  side  with 
the  intercostal,  and  below  with  the  abdominal  glands. 

The  Deep  lymphatic  vessels  of  the  thorax  are  the  intercostal,  in- 
ternal mammary,  and  diaphragmatic. 

The  Intercostal  lymphatic  vessels  follow  the  course  of  the  arteries 
of  the  same  name ;  and  reaching  the  vertebral  column  curve  down- 
wards, to  terminate  in  the  thoracic  duct. 

The  Internal  mammary  lymphatics  commence  in  the  parietes  of 
the  abdomen,  communicating  with  the  epigastric  lymphatics.  They 
ascend  by  the  side  of  the  internal  mammary  vessels,  being  joined  in 
their  course  by  the  anterior  intercostals,  and  terminate  on  the  right 
side  in  the  tributaries  of  the  ductus  lymphaticus  dexter;  and  on  the 
left  side  in  the  thoracic  duct.  The  diaphragmatic  lymphatics  pur- 
sue the  direction  of  their  corresponding  veins,  and  terminate,  some 
in  front  in  the  internal  mammary  vessels,  and  some  behind,  in  the 
posterior  mediastinal  lymphatics. 

The  Deep  lymphatic  glands  of  the  abdomen  are  the  lumbar  glands; 
they  are  very  numerous,  and  are  seated  around  the  common  iliac 
vessels,  the  aorta  and  vena  cava. 

The  deep  lymphatic  glands  of  the  pelvis  are  the  external  iliac, 
internal  iliac,  and  sacral. 

The  External  iliac  are  placed  around  the  external  iliac  vessels, 
being  in  continuation  by  one  extremity  with  the  femoral  lymphatics, 
and  by  the  other  with  the  lumbar  glands. 

The  Internal  iliac  glands  are  situated  in  the  course  of  the  internal 
iliac  vessels,  and  the  sacral  glands  are  supported  by  the  concave 
surface  of  the  sacrum. 

The  Deep  lymphatic  vessels  are  continued  upwards  from  the  thigh, 
beneath  Poupart's  ligament,  and  along  the  external  iliac  vessels  to 
the  lumbar  glands,  receiving  in  their  course  the  epigastric,  circum- 
flex ilii,  and  ilio-lumbar  lymphatic  vessels.  Those  from  the  parietes 
of  the  pelvis,  and  from  the  gluteal,  ischiatic,  and  obturator  vessels, 
follow  the  course  of  the  internal  iliac  arteries,  and  unite  with  the 
lumbar  lymphatics.  And  the  lumbar  lymphatic  vessels,  after  re- 
ceiving all  the  lymphatics  from  the  lower  extremities,  pelvis,  and 
loins,  terminate  by  several  large  trunks  in  the  receptaculum  chyli. 

LYMPHATICS  OF  THE  VISCERA. 

The  Lymphatic  vessels  of  the  lungs  are  distributed  over  every 
part  of  the  surface,  and  through  the  texture  of  these  organs ;  they 
converge  to  the  numerous  glands  situated  around  the  bifurcation  of 
the  trachea  and  roots  of  the  lungs — the  bronchial  glands.  Some  of 
these  glands  of  small  size,  may  be  traced  in  connexion  with  the 
bronchial  tubes  for  some  distance  into  the  lungs.  The  efferent 
vessels  from  the  bronchial  glands  unite  with  the  tracheal  and  oeso- 
phageal glands,  and  terminate  principally  in  the  thoracic  duct  at 
the  root  of  the  neck,  and  partly  in  the  ductus  lymphaticus  dexter. 
The  bronchial  glands,  in  the  adult,  present  a  variable  tint  of  brown. 


,  LYMPHATICS  OF  THE  LIVER.  353 

and  in  old  age  a  deep  black  colour.  In  infancy  they  have  none  of 
this  pigment,  and  are  not  to  be  distinguished  from  lymphatic  glands 
in  other  situations. 

The  Lymphatic  vessels  of  the  heart  originate  in  the  subserous  cel- 
lular tissue  of  the  surface,  and  in  the  deeper  tissues  of  the  organ, 
and  follow  the  course  of  the  vessels,  principally,  along  the  right 
border  of  the  heart  to  the  glands  situated  around  the  arch  of  the 
aorta  and  bronchial  glands,  whence  they  proceed  to  the  thoracic 
duct. 

The  Pericardiac  and  thymic  lymphatic  vessels  proceed  to  join  the 
anterior  mediastinal  and  bronchial  glands. 

The  Lymphatic  vessels  of  the  liver  are  divisible  into  the  deep  and 
superficial.  The  former  take  their  course  through  the  portal  canals, 
and  through  the  right  border  of  the  lesser  omentum,  to  the  lymphatic 
glands,  situated  in  the  course  of  the  hepatic  artery  and  along  the 
lesser  curve  of  the  stomach.  The  superficial  lymphatics  are  situated 
in  the  cellular  structure  of  the  proper  capsule,  over  the  whole  sur- 
face of  the  liver.  Those  of  the  convex  surface  are  divided  into  two 
sets; — 1.  Those  which  pass  from  before  backwards;  2.  Those 
which  advance  from  behind  forwards.  The  former  unite  to  form 
trunks,  which  enter  between  the  folds  of  the  lateral  ligaments  at  the 
right  and  left  extremities  of  the  organ,  and  of  the  coronary  ligament 
in  the  middle.  Some  of  these  pierce  the  diaphragm  and  join  the 
posterior  mediastinal  glands ;  others  converge  to  the  lymphatic  glands 
situated  around  the  inferior  cava.  Those  which  pass  from  behind 
forwards  consist  of  two  groups :  one  ascends  between  the  folds  of 
the  broad  ligament,  and  perforates  the  diaphragm,  to  terminate  in 
the  anterior  mediastinal  glands ;  the  other  curves  around  the  anterior 
margin  of  the  liver  to  its  concave  surface,  and  from  thence  to  the 
glands  in  the  right  border  of  the  lesser  omentum.  The  lymphatic 
vessels  of  the  concave  surface  are  variously  distributed,  according 
to  their  position ;  those  from  the  right  lobe  terminate  in  the  lumbar 
glands ;  those  from  the  gall-bladder  which  are  large  and  form  a 
remarkable  plexus,  enter  the  glands  in  the  right  border  of  the  lesser 
omentum ;  and  those  from  the  left  lobe  converge  to  the  lymphatic 
glands,  situated  along  the  lesser  curve  of  the  stomach. 

The  Lymphatic  glands  of  the  spleen  are  situated  around  its  hilus, 
and  those  of  the  pancreas  in  the  course  of  the  splenic  vein.  The 
lymphatic  vessels  of  these  organs  pass  through  their  respective  glands, 
and  join  the  aortic  glands,  previously  to  terminating  in  the  thoracic 
duct. 

The  Lymphatic  glands  of  the  stomach  are  of  small  size,  and  are 
situated  along  the  lesser  and  greater  curves  of  that  organ.  The 
lymphatic  vessels,  as  in  other  viscera,  are  superficial  and  deep,  the 
former  originating  in  the  subserous  and  the  latter  in  the  submucous 
tissue ;  they  pass  from  the  stomach  in  four  different  directions  :  some 
ascend  to  the  glands  situated  along  the  lesser  curve, — others  descend 
to  those  occupying  the  greater  curve, — a  third  set  passes  outwards 

45 


354  THORACIC  DUCT. 

to  the  splenic  glands,  and  a  fourth  to  the  glands  situated  near  the 
pylorus  and  to  the  aortic  glands. 

The  Lympliatic  glands  of  the  small  intestine  are  situated  between 
the  layei-s  of  the  mesentery,  in  the  meshes  formed  by  the  superior 
mesenteric  artery,  and  thence  named  mesenteric  glaiids.  These 
glands  are  most  numerous  and  largest,  superiorly,  near  to  the 
duodenum  ;  and,  inferiorly,  near  to  the  termination  of  the  ileum. 

The  Lymphatic  vessels  of  the  small  intestines  are  of  two  kinds : 
those  of  the  structure  of  the  intestines,  which  ramify  upon  its  sur- 
face previously  to  entering  the  mesenteric  glands  ;  and  those  which 
commence  in  the  villi,  upon  the  surface  of  the  mucous  membrane, 
and  are  named  lacteals. 

The  Lacteals  according  to  the  most  recent  and  best  researches — 
those  of  Dr.  Henle  of  Berlin — commence  in  the  centre  of  each  villus 
as  a  ccecal  tubulus,  which  opens  into  a  fine  network,  situated  in  the 
submucous  tissue.  From  this  areolar  network  the  lacteal  vessels 
proceed  to  the  mesenteric  glands,  and  from  thence  to  the  thoracic 
duct,  in  which  they  terminate. 

The  Lymphatic  glands  of  the  large  intestines  are  situated  along 
the  attached  margin  of  the  intestine,  in  the  meshes  formed  by  the 
arteries  previously  to  their  distribution.  The  lymphatic  vessels  take 
their  course  in  two  different  directions ;  those  of  the  coecum,  ascend- 
ing and  transverse  colon,  after  traversing  their  proper  glands,  pro- 
ceed to  the  mesenteric,  and  those  of  the  descending  colon  and  rectum 
to  the  lumbar  glands. 

The  Lymphatic  vessels  of  the  hidney  follow  the  direction  of  the 
blood-vessels  to  the  lumbar  ganglia  situated  around  the  aorta  and 
inferior  vena  cava ;  those  of  the  supra-renal  capsules,  which  are 
very  large  and  numerous,  terminate  in  the  renal  lymphatics. 

The  Lymphatic  vessels  of  the  viscera  of  the  pelvis  terminate  in  the 
sacral  and  lumbar  ganglia. 

The  Lymphatic  vessels  of  the  testicle  take  the  course  of  the  sper- 
matic cord  where  they  are  of  large  size,  as  is  shown  in  the  beautiful 
injections  made  by  Sir  Astley  Cooper ;  they  terminate  in  the  lumbar 
ganglia. 

THORACIC  DUCT. 

The  thoracic  duct  commences  in  the  abdomen,  by  a  considerable 
and  somewhat  triangular  dilatation,  the  receptaculum  chyli,  which  is 
situated  upon  the  front  of  the  body  of  the  second  lumbar  vertebra, 
behind  and  between  the  aorta  and  inferior  vena  cava,  and  close  to 
the  tendon  of  the  right  crus  of  the  diaphragm.  From  the  upper 
part  of  the  receptaculum  chyli,  the  thoracic  duct  ascends  through 
the  aortic  opening  in  the  diaphragm,  and  along  the  front  of  the  ver- 
tebral column,  lying  between  the  thoracic  aorta  and  vena  azygos,  to 
the  fourth,  dorsal  vertebra.  It  then  inclines  to  the  left  side,  passes 
behind  the  arch  of  the  aorta,  and  ascends  by  the  side  of  the  op.so- 


THORACIC  DUCT. 


355 


Fig.  123* 


phagus  and  behind  the  perpendicular  portion  of  the  left  subclavian 
artery  to  the  root  of  the  neck  opposite  the  seventh  cervical  vertebra, 
where  it  makes  a  sudden  curve  forwards  and  downwards,  and  ter- 
minates at  the  point  of  junction  of  the  left  subclavian  with  the  left 
internal  jugular  vein. 

The  thoracic  duct  is  equal  in  size  to  the  diameter  of  a  goose- 
quill  at  its  commencement  from  the 
receptaculum  chyh,  diminishes  consi- 
derably in  diameter  towards  the  middle 
of  the  posterior  mediastinum,  and  again 
becomes  dilated  near  its  termination. 
At  about  the  middle  of  its  course  it  fre- 
quently divides  into  two  branches  of 
equal  size,  which  reunite  after  a  short 
course ;  and  sometimes  it  gives  off  se- 
veral branches,  which  assume  a  plexi- 
form  arrangement  in  this  situation.  Oc- 
casionally the  thoracic  duct  bifurcates 
at  the  upper  part  of  the  thorax  into  two 
branches,  one  of  which  opens  into  the 
point  of  junction  between  the  right  sub- 
clavian and  jugular  veins,  while  the 
other  proceeds  to  the  normal  termina- 
tion of  the  duct  on  the  left  side.  In  rare 
instances  the  duct  has  been  found  to 
terminate  in  the  vena  azygos  which  is 
its  normal  destination  in  some  Mam- 
malia. 

The  thoracic  duct  presents  fewer 
valves  in  its  course  than  lymphatic 
vessels  generally ;  at  its  termination  it 
is  provided  with  a  pair  of  semilunar 
valves  which  prevent  the  admission  of 
venous  blood  into  its  cylinder. 

Branches. — The  thoracic  duct  re- 
ceives at  its  commencement  four  or 
five  large  lymphatic  trunks  which  unite 
to  form  the  receptaculum  chyli ;  it  next  receives  the  trunks  of  the 

*  The  course  and  termination  of  the  thoracic  duct.  1.  The  arch  of  llic  aorta.  2. 
The  thoracic  aorta.  3.  The  abdomhial  aorta ;  showing-  its  principal  branches  divided 
near  their  origin.  4.  The  arteria  innominata,  dividing  into  the  right  carotid  and  right 
subclavian  arteries.  5.  The  left  carotid.  6.  The  left  subclavian.  7.  The  superior 
cava,  formed  by  the  union  of  8,  tlie  two  venEB  innominataj ;  and  these  by  the  junction 
9,  of  the  internal  jugular  and  subclavian  vein  at  each  side.  1 0.  The  greater  vena 
azygos.  11.  The  termination  of  the  lesser  in  the  greater  vena  azygos.  12.  The  re- 
ceptaculum chyli;  several  lymphatic  trunks  are  seen  opening  into  it.  13.  The  tho- 
racic duct,  dividing  opposite  the  middle  of  the  dorsal  vertebrtE  into  two  branches 
which  soon  reunite  ;  the  course  of  the  duct  behind  the  arch  of  the  aorta  and  left  sub- 
clavian artery  is  shown  by  a  dotted  line.  14.  The  duct  making  its  turn  at  the  root  of 
the  neck  and  receiving  several  lymphatic  trunks  previously  to  terminating  in  the  pos- 
terior aspect  of  the  junction  of  the  internal  jugular  and  subclavian  vein.  15.  Tiie 
termination  of  the  trunk  of  the  ductus  lymphaticus  de.xter. 


356  RIGHT  THORACIC  DUCT. 

lacteal  vessels.  Within  the  thorax  it  is  joined  by  a  large  lymphatic 
trunk  from  the  Uver,  and  in  its  course  through  the  posterior  medias- 
tinum, receives  the  lymphatic  vessels  both  from  the  viscera  and 
from  the  parietes  of  the  thorax.  At  its  curve  forwards  in  the  neck 
it  is  joined  by  the  lymphatic  trunks  from  the  left  side  of  the  head 
and  neck,  left  upper  extremity,  and  from  the  upper  part  of  the 
thorax,  and  thoracic  viscera. 

The  Ductus  lymp/iaticus  dexter  is  a  short  trunk  which  receives 
the  lymphatic  vessels  from  the  right  side  of  the  head  and  neck, 
right  upper  extremity  and  right  side  of  the  thorax,  and  terminates 
at  the  junction  of  the  right  subclavian  with  the  right  internal  jugular 
vein,  at  the  point  where  these  veins  unite  to  form  the  right  vena 
innominata.  It  is  provided  at  its  termination  with  a  pair  of  semi- 
lunar valves,  which  prevent  the  entrance  of  blood  from  the  veins. 


CHAPTER    VIII. 


ON  THE  NERVOUS  SYSTEM. 


The  nervous  system  consists  of  a  central  organ,  the  cerebro- 
spinal centre  of  axis,  and  of  numerous  rounded  and  flattened  white 
cords, — the  nerves,  which  are  connected  by  one  extremity  with  the 
cerebro-spinal  centre,  and  by  the  other  are  distributed  to  all  the 
textures  of  the  body.  The  sympathetic  system  is  an  exception  to 
this  description ;  for  in  place  of  one  it  has  many  small  centres 
which  are  called  ganglia,  and  which  communicate  very  freely  with 
the  cerebro-spinal  axis  and  with  its  nerves. 

The  cerebro-spinal  axis  consists  of  two  portions,  the  brain,  an 
organ  of  large  size,  situated  within  the  skull,  and  the  spinal  cord,  a 
lengthened  portion  of  the  nervous  centre  continuous  with  the  brain, 
and  occupying  the  canal  of  the  vertebral  column. 

The  most  superficial  examination  of  the  brain  and  spinal  cord 
shows  them  to  be  composed  of  fibres,  which  in  some  situations  are 
ranged  side  by  side  or  collected  into  bundles  or  fasciculi,  and  in 
other  situations  are  intei'laced  at  various  angles  by  cross  fibres. 
The  fibres  are  connected  and  held  together  by  a  delicate  cellular 
web,  which  forms  the  bond  of  support  to  the  entire  organ.  It  is 
also  observed  that  the  cerebro-spinal  axis  presents  two  substances 
differing  from  each  other  in  density  and  colour  ;  a  gray  or  cineri- 
tious  or  cortical  substance,  and  a  white  or  medullary  substance. 
The  gray  substance  forms  a  thin  lamella  over  the  entire  surface  of 
the  convolutions  of  the  cerebrum,  and  the  laminas  of  the  cerebellum : 
hence  it  has  been  named  cortical ;  but  the  gray  substance  is  not 
confined  to  the  surface  of  the  brain,  as  this  term  would  imply,  it  is 
likewise  situated  in  the  centre  of  the  spinal  cord  its  entire  length, 
and  may  be  thence  traced  through  the  medulla  oblongata,  crura 
cerebri,  thalami  optici,  and  corpora  striata ;  it  enters  also  into  the 
composition  of  the  lobus  perforatus,-  tuber  cinereum,  commissura 
mollis,  pineal  gland,  and  corpus  rhomboideum. 

The  fibres  of  the  cerebro-spinal  axis  are  arranged  into  two  classes, 
diverging  and  converging.  The  diverging  fibres  proceed  from  the 
medulla  oblongata,  and  diverge  to  every  part  of  the  surface  of  the 
brain  ;  while  the  converging  commence  upon  the  surface,  and  pro- 
ceed inwards  towards  the  centre  so  as  to  connect  the  diverging 
fibres  of  opposite  sides.  In  certain  parts  of  their  course  the 
diverging  fibres  are  separated  by  the  gray  substance,  and  increase 


358  ?;ERvors  system — developement. 

in  number  so  as  to  form  a  body  of  considerable  size,  which  is  called 
a  o-ancrlion.  The  position  and  mutual  relations  of  these  fibres  and 
ganglia  may  be  best  explained  by  reference  to  the  mode  of 
developement  of  the  cerebro-spinal  axis  in  animals  and  in  man. 

The  centre  of  the  nervous  system  in  the  lowest  animals  possessed 
of  a  lengthened  axis,  presents  itself  in  the  form  of  a  double  cord. 
A  step  higher  in  the  animal  scale,  and  knots  or  ganglia  are 
developed  upon  one  extremity  of  this  cord  ;  such  is  the  most  rudi- 
mentary condition  of  the  brain  in  the  lowest  forms  of  vertebrata. 
In  the  lowest  fishes  the  anterior  extremity  of  the  double  cord  dis- 
plays a  succession  of  five  pairs  of  ganglia.  The  higher  fishes  and 
amphibia  appear  to  have  a  different  disposition  of  these  primitive 
ganglia.  The  first  two  have  become  fused  into  a  single  ganglion, 
and  then  follow  only  three  pairs  of  symmetrical  ganglia.  But  if  the 
lai'ger  pair  be  unfolded  after  being  hardened  in  alcohol,  it  will  then 
be  seen  that  the  whole  number  of  ganglia  exists,  but  that  four  have 
become  concealed  by  a  thin  covering  that  has  spread  across  them. 
This  condition  of  the  brain  carries  us  upwards  in  the  animal 
scale  even  to  Mammalia ;  e.  g.,  in  the  dog  or  cat  we  find,  first  a 
single  ganglion,  the  cerebellum,  then  three  pairs  following  each 
other  in  succession ;  and  if  we  unfold  the  middle  pair,  we  shall  be 
at  once  convinced  that  it  is  indeed  composed  of  two  pairs  of  pri- 
mitive ganglia  concealed  by  an  additional  developement.  Again 
it  will  be  observed,  that  the  primitive  ganglia  of  opposite  sides,  at 
first  separate  and  disjoined,  become  connected  by  means  of  trans- 
verse fibres  of  communication  {commissures,  commissura,  a  joining). 
The  office  of  these  commissures  is  the  association  in  function  of 
the  two  symmetrical  portions.  Hence  we  arrive  at  the  general  and 
important  conclusion,  that  the  brain  among  the  lower  animals  con- 
sists of  pnmiiive  cords,  primitive  ganglia  upon  those  cords,  and 
commissures  which  connect  the  substances  of  the  adjoining  ganglia, 
and  associate  their  functions. 

In  the  developement  of  the  cerebro-spinal  axis  in  man,  the  earliest 
indication  of  the  spinal  cord  is  presented  under  the  form  of  a  pair 
of  minute  longitudinal  filaments  placed  side  by  side.  Upon  these, 
towards  the  anterior  extremity,  five  pairs  of  minute  swellings  are 
observed,  not  disposed  in  a  straight  line  as  in  fishes,  but  curved 
upon  each  other  so  as  to  correspond  with  the  direction  of  the  future 
cranium.  The  posterior  pair  soon  becomes  cemented  upon  the  middle 
line;  forming  a  single  ganglion  ;  the  second  pair  also  unite  with  each 
other ;  the  third  and  fourth  pairs,  at  first  distinct,  are  speedily  veiled 
by  a  lateral  developement,  which  arches  backwards  and  conceals 
them ;  the  anterior  pairs,  at  first  very  small,  decrease  in  size  and 
become  almost  lost  in  the  increased  developement  of  the  preceding 
pairs. 

We  sec  here  a  chain  of  resemblances  corresponding  with  the  pro- 
gressive developement  observed  in  the  lower  animals;  the  human 
brain  is  passing  through  the  ])hasos  of  improving  developement, 
which  distinguish  the  higher  from  the  lower  creatures :  and  we  are 


NERVOUS  SYSTEM STRUCTURE,  359 

naturally  led  to  the  same  conclusion  with  regard  to  the  architecture 
of  the  human  brain,  that  we  were  led  to  estabUsh  as  the  principle 
of  developement  in  the  inferior  creatures— that  it  is  composed  of 
primitive  cords,  'primitive  ganglia  upon  those  cords,  commissures 
to  connect  those  ganglia,  and  developements  from  those  ganglia. 

In  the  adult,  the  primitive  longitudinal  cords  have  become  cement- 
ed together,  to  form  the  spinal  cord.  But,  at  the  upper  extremity, 
they  separate  from  each  other  under  the  name  of  crura  cerebri. 
The  first  pair  of  ganglia  developed  from  the  primitive  cords,  have 
grown  into  the  cerebellum;  the  second  pair  (the  optic  lobes  of 
animals)  have  become  the  corpora  guadrigemina  of  man.  The 
third  pair,  the  optic  thalami,  and  the  fourth,  the  cmyora  striata,  are 
the  basis  of  the  hemispheres,  which,  the  merest  lamina  in  the  fish, 
has  become  the  largest  portion  of  the  brain  in  man.  And  the  fifth 
pair  (olfactory  lobes),  so  large  in  the  lowest  forms,  have  dwindled 
into  the  olfactorij  bulbs  of  man. 

The  white  substance  of  the  brain  and  spinal  cord  when  examined 
with  the  microscope,  is  found  to  consist  of  fibres  varying  in  diameter, 
according  to  Krause,  from  the  ■^\-^  to  the  y|-j  of  a  line.  These 
fibres  are  composed  of  a  thin  and  transparent  neurilemma,  en- 
closing a  soft  homogeneous  nervous  substance,  and  they  possess  a 
remarkable  tendency,  when  compressed,  to  assume  a  varicose  ap- 
pearance. The  nervous  fibres  of  the  olfactory,  optic,  and  auditory 
nerves  have  the  same  disposition  to  become  varicose  on  pressure. 
The  neurilemma  of  the  primitive  fibre,  according  to  Fontana,  con- 
sists of  two  layers,  of  which  the  internal  is  thin  and  transparent, 
and  the  external  cellular  and  less  transparent. 

The  gray  substance  of  the  brain,  according  to  Valentin,  is  com- 
posed of  spherical  globules  of  considerable  size,  having  a  central 
nucleus,  and  near  the  margin  of  the  latter  another  smaller  nucleus, 
and  frequently  upon  the  surface  of  the  globule,  patches  of  pigment. 
Numerous  minute  fibres  have  been  observed  by  Remak  to  proceed 
from  the  surface  of  these  globules,  and  are  supposed  to  maintain  a 
communication  with  surrounding  globules.  The  various  shades  of 
gray  observed  in  different  parts  of  the  brain,  depend  upon  the 
greater  or  smaller  number  of  globules  existing  in  those  parts.  Two 
kinds  of  gray  substance  are  described  by  Rolando  as  existing  in 
the  spinal  cord ;  the  one  {substantia  cinerea  spongiosa  vasculosa)  is 
the  ordinary  gray  matter  of  the  cord,  and  the  other  {substantia 
cinerea  gelatinosa)  forms  part  of  the  posterior  cornua.  The  former 
resembles  the  gray  matter  of  the  brain,  consisting  of  globules,  while 
the  latter  is  composed  of  small  bodies  resembling  the  blood  corpus- 
cules  of  the  frog. 

The  nerves  are  divisible  into  two  great  classes, — those  which 
proceed  directly  from  the  cerebro-spinal  axis,  the  cranial  and 
spinal  nerves,  and  constitute  the  system  of  animal  life ;  and  those 
which  originate  from  a  system  of  nervous  centres,  independent  oi 
the  cerebro-spinal  axis,  but  closely  associated  with  that  centre  by 


360  CLASSIFICATION  OF  NERVES. 

numerous  communications,  the  sympathetic  system,  or  system  of 
organic  hfe. 

The  division  of  nerves  into  cranial  and  spinal  is  purely  arbitrary, 
and  depends  upon  the  circumstance  of  the  former  passing  through 
the  foramina  of  the  cranium,  and  the  latter  through  those  of  the 
vertebral  column.  With  respect  to  origin, — all  the  cranial  nerves, 
with  the  exception  of  the,  first, — olfactory,  proceed  from  the  spinal 
cord,  or  from  its  immediate  continuation  into  the  brain.  The  spinal 
nerves  arise  by  two  roots ;  anterior,  which  proceeds  from  the 
anterior  segment  of  the  spinal  cord,  and  possess  a  motor  function ; 
and  posterior,  which  is  connected  with  the  posterior  segment,  and 
bestows  the  faculty  of  sensation.  The  motor  nerves  of  the  cranium 
are  shown  by  dissection  to  be  continuous  with  the  motor  portion  of 
the  cord,  and  form  one  system  with  the  motor  roots  of  the  spinal 
cord ;  while  the  nerves  of  sensation,  always  excepting  the  olfactory, 
are  in  like  manner  traced  to  the  posterior  segment  of  the  cord,  and 
form  part  of  the  system  of  sensation.  To  these  two  systems  a  third 
has  been  added  by  Sir  Charles  Bell, — the  respiratory  system, — ■ 
which  consists  of  nerves  associated  in  the  function  of  respiration, 
and  arising  from  the  side  of  the  upper  part  of  the  spinal  cord  in 
one  continuous  line,  which  was  thence  named,  by  that  distinguished 
physiologist,  the  respiratory  tract.  The  microscope  has  succeeded 
in  making  no  structural  distinction  between  the  anterior  and  pos- 
terior roots  of  the  spinal  nerves ;  but  the  latter  are  remarkable  from 
possessing  a  ganglion  near  to  their  attachment  with  the  cord.  This 
ganglion  is  observed  upon  the  posterior  roots  of  all  the  spinal  nerves, 
and  also  upon  the  corresponding  root  of  the  fifth  cranial  nerve, 
which  is  thence  considered  a  spinal  cranial  nerve.  Upon  others  of 
the  cranial  nerves  a  ganglion  is  found,  which  associates  them  in 
their  function  with  the  nerves  of  sensation,  and  establishes  an 
analogy  with  the  spinal  nerves. 

The  recent  researches  of  Mr.  Grainger  have  made  an  important 
addition  to  our  knowledge  of  the  mode  of  connexion  of  the  nerves 
with  the  spinal  cord ;  he  has  shown  that  both  roots  of  the  spinal 
nerves,  as  well  as  most  of  the  cerebral,  divide  into  two  sets  of  fila- 
ments upon  entering  the  cord,  one  set  being  connected  to  the  gray 
substance,  while  the  other  is  continuous  with  the  white  or  fibrous 
part  of  the  cord.  The  former  he  considers  to  be  the  agents  of  the 
excito-motory  system  of  Dr.  Marshall  Hall ;  and  the  latter,  the 
communication  with  the  brain  and  the  medium  for  the  transmission 
of  sensation  and  volition.  He  has  not  been  able  to  trace  the  fibres 
which  enter  the  gray  substance  to  their  termination  ;  but  he  thinks 
it  probable  that  the  ultimate  filaments  of  the  posterior  root  join  those 
of  the  anterior  root ;  or  in  the  words  of  Dr.  Marshall  Hall's  system, 
that  the  incident  fibres  (sensitive)  are  continuous  with  the  reflex 
(motor). 

The  connexion  of  a  nerve  with  the  cerebro-spinal  axis  is  called, 
for  convenience  of  description,  its  origin :  this  term  must  not,  how- 


NERVES — STRUCTURE COMMUNICATIONS.  361 

ever,  be  received  literally ;  for  each  nerve  is  developed  in  the  pre- 
cise situation  which  it  occupies  in  the  body,  and  with  the  same  rela- 
tions that  it  possesses  in  after  life.  Indeed,  ,we  not  unfrequently 
meet  with  instances  in  anencephalous  foetuses  where  the  nerves  are 
beautifully  and  completely  formed,  while  the  brain  and  spinal  cord 
are  wholly  wanting.  The  word  origin  must,  therefore,  be  consi- 
dered as  a  relic  of  the  darkness  of  preceding  ages,  when  the 
cerebro-spinal  axis  was  looked  upon  as  the  tree  from  which  the 
nerves  pushed  forth  as  branches.  In  their  distribution  the  spinal 
nerves  for  the  most  part  follow  the  course  of  the  arteries,  particu- 
larly in  the  limbs,  where  they  lie  almost  constantly  to  the  outer  side 
and  superficially  to  the  vessels,  as  if  for  the  purpose  of  receiving 
the  first  intimation  of  danger  and  of  communicating  it  to  the  mus- 
cles, that  they  may  instantly  remove  the  arteries  from  impending 
injury. 

The  microscopic  examination  of  a  cerebro-spinal  nerve  shows  it 
to  be  composed  of  minute  fibres,  resembling  those  of  the  brain,  and 
consisting  of  a  neurilemma  enclosing  a  soft,  homogeneous  nervous 
substance.  The  chief  difference  betvt^een  the  fibres  of  the  nerves 
and  the  cerebral  fibres  is  a  somewhat  greater  opacity  and  more 
granular  appearance  of  the  contents  of  the  minute  cylinders  of  the 
former;  a  greater  thickness  of  their  neurilemma,  and  an  indisposition 
to  the  formation  of  varicose  enlargements  upon  compression.  The 
neurilemma  presents  the  same  two  layers  whicPi  exist  in  the  cere- 
bral fibres.  The  primitive  fibres,  or  filaments,  are  assembled  into 
small  bundles  and  enclosed  in  a  distinct  sheath,  constituting  ^.  funi- 
culus; the  funiculi  are  collected  into  larger  bundles  or  fasciculi,  and 
a  single  fasciculus  or  a  number  of  fasciculi  connected  by  cellular 
tissue,  and  invested  by  a  membranous  sheath,  constitute  a  nerve. 
The  funiculi,  when  freshly  exposed,  present  a  peculiar  zigzag  line 
across  their  cylinder,  which  is  most  probably  produced  by  the 
arrangement  of  the  primitive  fibres,  or  possibly  by  some  condition 
of  th^  neurilemma.  This  appearance  is  destroyed  by  making  exten- 
sion upon  the  nerve. 

Communications  between  nerves  take  place  either  by  means  of 
the  funiculi  composing  a  single  nerve,  or  of  the  fasciculi  in  a  nervous 
plexus.  In  these  communications  there  is  no  fusion  of  nervous  sub- 
stance, the  cord  formed  by  any  two  funiculi  is  constantly  enlarged, 
and  corresponds  accurately  with  their  combined  bulk.  Microscopic 
examination  substantiates  this  observation,  and  shows  that  the  pri-  ■ 
mitive  fibre  passes  unchanged  from  one  funiculus  to  the  other,  so 
that  the  primitive  fibre  is  single  and  uninterrupted  from  its  connec- 
tion with  the  cerebro-spinal  axis  to  its  terminal  distribution.  A 
nervous  plexus  consists  in  a  communication  between  the  fascicuH 
and  funiculi  composing  the  nerves,  which  are  associated  in  their 
supply  of  a  limb  or  of  a  certain  region  of  the  body.  During  this 
communication  there  is  an  interchange  of  funiculi,  and  with  the 
funiculi  an  interchange  of  fibres. 

The  Sympathetic  system  consists  of  numerous  ganglia,  of  commu- 

46 


362  BRAIN SIE3IBRANES. 

nicating  branches  passing  between  the  ganglia,  of  others  passing 
between  the  gangUa  and  the  cerebro-spinal  axis,  and  of  branches  of 
distribution  which  are  remarkable  for  their  frequent  and  plexiform 
communications.  The  sympathetic  nerves  also  differ  from  other 
nerves  in  their  colour,  which  is  of  a  grayish  pearly  tint.  Examined 
with  the  microscope  the  sympathetic  nerves  are  seen  to  be  composed 
of  an  admixture  of  gray  and  white  fibres ;  the  white  fibres  belong  to 
the  cerebro-spinal  system:  the  gray  are  much  smaller  than  the 
white,  less  transparent,  and  the  neurilemma  is  less  easily  distinguish- 
able from  its  contents:  some  of  the  nerves  are  composed  of  gray 
fibres  only,  without  any  admixture  of  white.  The  sympathetic  gan- 
glia contain  the  globules  observed  in  the  gray  substance  of  the 
brain;  they  are  firmer  in  structure  and  enclosed  in  a  strong  invest- 
ing capsule.  The  fasciculi  of  fibres  entering  the  ganglion  become 
divided  and  form  a  plexus  around  the  globules;  they  then  con- 
verge to  constitute  another  fasciculus,  by  which  they  quit  the 
ganglion. 

The  nervous  system  may  be  divided  for  convenience  of  descrip- 
tion into  1.  The  brain.  2.  The  spinal  cord.  3.  The  cranial  nerves. 
4.  The  spinal  nerves.     5.  The  sympathetic  system. 

THE  BRAIiV. 

The  brain  is  a  collective  term  which  signifies  those  parts  of  the 
nervous  system,  exclusive  of  the  nerves  themselves,  whi'ch  are  con- 
tained within  the  cranium ;  they  are  the  cerebrum,  cerebellum,  and 
medulla  oblongata.  These  are  invested  and  protected  by  the  mem- 
branes of  the  brain,  and  the  whole  together  constitute  the  encephalon 
(ev,  xs^akrj,  within  the  head). 

MEMBRANES  OF  THE  ENCEPHALON. 

Dissection. — To  examine  the  encephalon  with  its  membranep,  the 
upper  part  of  the  skull  must  be  removed  by  sawing  througn  the 
external  table,  and  breaking  the  internal  table  with  the  chisel  and 
hammer.  After  the  calvarium  has  been  loosened  all  round,  it  will 
require  a  considerable  degree  of  force  to  tear  the  bone  away  from 
the  dura  mater.  This  adhesion  is  particularly  firm  at  the  sutures, 
where  the  dura  mater  is  continuous  with  a  membranous  layer  inter- 
posed between  the  edges  of  the  bones ;  in  other  situations,  the  con- 
nexion results  from  numerous  vessels  which  permeate  the  inner 
table  of  the  skull.  The  adhesion  subsisting  between  the  dura  mater 
and  bone  is  greater  in  the  young  subject  than  in  the  adult. 

Upon  being  torn  away,  the  internal  table  will  present  the  deeply 
grooved  and  ramified  channels,  corresponding  with  the  branches  of 
the  arteria  mcningea  magna.  Along  the  middle  line  will  be  seen  a 
groove  corresponding  with  the  superior  longitudinal  sinus,  and  on 
either  side  may  be  frequently  observed  some  depressed  fossae,  cor- 
responding with  the  Pacchionian  bodies. 


DURA  MATER.  363 

The  membranes  of  the  encephalon  are  the  dura  mater,  arachnoid 
membrane,  and  fia  mater. 

The  Dura  mater*  is  the  firm,  bluish,  fibrous  membrane,  which  is 
exposed  on  the  removal  of  the  calvarium.  It  fines  the  anterior 
of  the  skufi  and  spinal  column,  and  sends  processes  inwards 
for  the  support  and  protection  of  the  difterent  parts  of  the 
brain.  It  also  sends  processes  externally,  which  form  sheaths  for 
the  nerves  as  they  quit  the  skull  and  spinal  column.  Its  external 
surface  is  rough  and  fibrous,  and  corresponds  with  the  internal  table 
of  the  skull.  The  internal  surface  is  smooth,  and  lined  by  the  thin 
varnish-like  lamella  of  the  arachnoid  membrane.  The  latter  is  a 
serous  membrane.  Hence  the  dura  mater  becomes  a  fibro-serous 
membrane,  being  composed  of  its  own  proper  fibrous  structure,  and 
the  serous  layer  derived  from  the  arachnoid.  There  are  two  other 
instances  of  fibro-serous  membrane  in  the  body,  formed  in  the  same 
way — the  pericardium  and  tunica  albuginea  of  the  testicle. 

On  either  side  of  the  dura  mater  the  branches  of  the  middle  me- 
ningeal artery  may  be  seen  ramifying ;  and  in  the  middle  line  is  a 
depressed  groove,  formed  by  the  subsidence  of  the  upper  wall  of  the 
superior  longitudinal  sinus.  If  the  sinus  be  opened  along  its  course, 
it  will  be  found  to  be  a  triangular  channel,  crossed  at  its  lower 
angle  by  numerous  white  bands,  called  chordee  Willisii  ;f  granular 
bodies  are  also  occasionally  seen  in  its  interior ;  these  are  glandulce 
Pacchioni. 

The  GlanduIcB  Pacchioni'^  are  small,  round,  whitish  granulations, 
collected  into  clusters  of  variable  size.  They  are  found  in  three 
situations.  1.  On  the  inner  surface  of  the  dura  mater  near  to  the 
superior  longitudinal  sinus  ;  when  of  large  size  they  produce  absorp- 
tion of  the  dura  mater,  and  considerable  indentations  on  the  inner 
wall  of  the  skull.  2.  In  the  superior  longitudinal  sinus.  3.  On  the 
arachnoid  membrane  investing  the  pia  mater  near  to  the  margin  of 
the  hemispheres. 

If  the  student  cut  through  one  side  of  the  dura  mater,  along  the 
line  of  his  incision  through  the  skull,  and  turn  it  upwards  towards 
the  middle  line,  he  will  observe  the  smooth  internal  surface  of  the 
dura  mater.  He  will  perceive  also  the  large  cerebral  veins  filled 
with  dark  blood,  passing  from  behind  forwards  to  open  into  the 
superior  longitudinal  sinus,  and  the  firm  connexions,  by  means  of 
these  veins  and  the  Pacchionian  bodies,  between  the  opposed  sur- 
faces of  the  arachnoid  membrane. 

If  he  separate  these  with  his  scalpel,  he  will  see  a  vertical  layer 

*  So  named  from  a  supposition  that  it  was  the  source  of  all  the  fibrous  membranes 
of  the  body. 

t  Willis  lived  in  the  seventeenth  century ;  he  was  a  great  defender  of  the  opinions  of 
Harvey. 

t  These  bodies  have  no  analogy  whatsoever  with  glands.  Their  nature  and  use  are 
but  imperfectly  known.  They  are  not  found  in  infancy.  Tliey  arc  described  as  con- 
globate glands  by  Pacchioni,  in  an  epistolary  dissertation.  "De  Glandulis  conglobatis 
DuriE  Meningis  indeque  ortis  Lymphaticis  ad  Piam  Matrem  productis,"  published  in 
Rome,  in  1705. 


364  DURA  JMATER PROCESSES. 

of  dura  mater  descending  between  the  hemispheres,  and  if  he  draw 
one  side  of  the  brain  a  httle  outwards,  he  will  distinctly  perceive  its 
extent;  this  is  the  falx  cerebri. 

The  processes  of  dura  mater  which  are  sent  inwards  towards  the 
interior  of  the  skull,  are  the  falx  cerebri,  tentorium  cerebelli,  and 
falx  cerebelli. 

The  Falx  cerebri  (falx,  a  sickle),  so  named  from  its  sickle-like 
appearance,  narrow  in  front,  broad  behind,  and  forming  a  sharp 
curved  edge  below,  is  attached  in  front  to  the  crista  galli  process  of 
the  ethmoid  bone,  and  behind  to  the  tentorium  cerebelli. 

The  Tentorium  cerebelli  (tentorium,  a  tent)  is  a  roof  of  "dura 
mater,  thrown  across  the  cerebellum  and  attached  at  each  side  to 
the  margin  of  the  petrous  portion  of  the  temporal  bone,  behind  to 
the  transverse  ridge  of  the  occipital  bone,  which  lodges  the  lateral 
sinuses,  and  to  the  clinoid  processes  in  front.  It  supports  the  poste- 
rior lobes  of  the  cerebrum  and  prevents  their  pressure*  on  the 
cerebellum,  leaving  only  a  small  opening  anteriorly,  for  the  trans- 
mission of  the  crura  cerebri. 

The  Falx  cerebelli  is  a  small  process,  generally  double,  attached 
to  the  vertical  ridge  of  the  occipital  bone  beneath  the  lateral  sinus, 
and  to  the  tentorium.  It  is  received  into  the  indentation  between 
the  two  lateral  lobes  of  the  cerebellum. 

The  layers  of  the  dura  mater  separate  in  several  situations,  so  as 
to  form  irregular  channels  which  receive  the  venous  blood.  These 
are  the  sinuses  of  the  dura  mater;  they  are  described  at  page  331, 
in  the  Chapter  on  the  Veins. 

The  student  cannot  see  the  tentorium  and  falx  cerebelli  until  the 
brain  is  removed  ;  but  he  should  consider  the  attachments  of  the 
tentorium  upon  the  dried  skull,  for  he  will  have  to  divide  it  in  the 
removal  of  the  brain.  He  should  now  proceed  to  that  operation, 
for  which  purpose  the  dura  mater  is  to  be  incised  all  round,  on  a 
level  with  the  section  through  the  skull,  and  the  scissors  are  to  be 
cai'ried  deeply  between  the  hemispheres  of  the  brain  in  front,  to  cut 
through  the  anterior  part  of  the  falx ;  then  draw  the  dura  mater 
backwards,  and  leave  it  hanging  by  its  attachment  to  the  tentorium, 
liaise  the  anterior  lobes  of  the  brain  carefully  with  the  hand,  and 
lift  the  olfactory  bulbs  from  the  cribriform  fossas  with  the  handle  of 
the  scalpel.  Then  cut  across  the  two  optic  nerves  and  internal 
carotid  arteries.  Next  divide  the  infundibulum  and  third  nerve,  and 
carry  the  knife  along  the  margin  of  the  petrous  bone  at  each  side, 
so  as  to  divide  the  tentorium  near  its  attachment.  Cut  across  the 
fourth,  fifth,  sixth,  seventh,  and  eighth  nerves  in  succession  with  a 
sharp  knife,  and  pass  the  scalpel  as  far  down  as  possible  into  the 
vertebral  canal,  to  sever  the  spinal  cord,  cutting  first  to  one  side 
and  then  to  the  other,  in  order  to  divide  the  vertebral  arteries  and 
first  cervical  nerves.     Then  let  him  press  the  cerebellum  gently  for- 

*  In  le;tpin^  animalH,  as  tlic  feline  and  canine  gomwa.,  the  tentorium  forms  a  bony 
tent. 


ARACHNOID  MEMBRANE.  365 

wards  with  the  fingers  of  the  right  hand,  the  hemispheres  being 
supported  with  the  left,  and  the  brain  will  roll  into  his  hand. 

The  Arteries  of  the  dura  mater  are  the  anterior  meningeal  from 
the  internal  carotid.  The  middle  meningeal  and  meningea  varva 
from  the  internal  maxillary.  The  inferior  meningeal  from  the  as- 
cending pharyngeal  and  occipital  arteries ;  and  the  posterior  menin- 
geal from  the  vertebral. 

The  Nerves  are  derived  from  the  nervi  molles  and  vertebral  plexus 
of  the  sympathetic,  from  the  Casserian  gangUon,  the  ophthalmic 
nerve,  and  sometimes  from  the  fourth.  The  branches  from  the  two 
last  are  given  off  while  the  nerves  are  situated  by  the  side  of  the 
sella  turcica  ;  they  are  recurrent  and  pass  backwards  between  the 
layers  of  the  tentorium,  to  the  lining  membrane  of  the  lateral  sinus. 

Arachnoid  Membrane. 

The  Arachnoid  (d^a-xyn,  sTSos,  like  a  spider's  web),  so  named  from 
its  extreme  tenuity,  is  the  serous  membrane  of  the  cerebro-spinal 
centre,  and,  like  other  serous  membranes,  a  shut  sac.  It  envelopes 
the  brain  and  spinal  cord,  and  is  reflected  upon  the  inner  surface  of 
the  dura  mater,  giving  to  that  membrane  its  serous  investment. 

The  arachnoid  is  thin  and  transparent  on  the  upper  surface  of  the 
brain,  and  may  be  demonstrated  by  inserting  a  blowpipe,  and  inject- 
ing beneath  it  a  stream  of  air.  In  other  situations,  as  at  the  base  of 
the  brain  and  between  the  cerebellum  and  medulla  oblongata,  it  is 
semi-transparent  and  dense  in  structure,  and  is  rendered  very  evi- 
dent by  passing  across  from  one  convexity  to  another,  and  leaving 
a  considerable  space  between  it  and  the  brain..  The  space  which  is 
thus  formed  between  the  arachnoid  membrane  and  the  interval  of 
the  base  of  the  brain  between  the  two  middle  lobes  of  the  hemi- 
spheres, has  been  called  by  Cruveilhier  the  anterior  suh-araclinoidean 
space ;  and  that  intervening  between  the  posterior  and  under  part  of 
the  cerebellum  and  the  medulla  oblongata,  the  posterior  sub-aracb- 
noidean  space.  Both  these  spaces  communicate  with  each  other 
across  the  crura  cerebelli.  In  inflammation  of  the  meninges,  this 
membrane  is  often  thickened  and  opaque. 

The  arachnoid  is  attached  to  the  pia  mater  of  the  brain  by  a  loose 
cellular  tissue,  the  sub-arachnoidean.  This  tissue  is  filamentous  at 
the  base  of  the  brain,  and  between  the  hemispheres.  Around  the 
spinal  cord  the  arachnoid  is  disposed  very  loosely  so  as  to  leave  a 
considerable  space  between  it  and  the  spinal  cord.  The  spinal  sub- 
arachnoidean  space  is  divided  by  a  partial  longitudinal  septum  which 
serves  to  connect  the  arachnoid  with  the  posterior  surface  of  the 
spinal  cord. 

The  Sub-arachnoidean  cellular  tissue  and  the  sub-arachnoidean 
spaces  are  the  seat  of  an  abundant  serous  secretion,  the  sub-arach- 
%oidean  Jiuid,  which  fills  all  the  vacuities  existing  between  the 
arachnoid  and  pia  mater,  and  distends  the  arachnoid  of  the  spinal 
cord  so  completely,  as  to  enable  it  to  occupy  the  whole  of  the  space 
included  in  the  sheath  of  dura  mater. 


366  PIA  jVIATER CEREBRUM. 

The  arachnoid  also  secretes  a  serous  fluid  from  its  inner  surface, 
which  is  small  in  quantity  compared  with  the  sub-arachnoidean 
liquid. 

"The  arachnoid  does  not  enter  into  the  ventricles  of  the  brain,  as 
imagined  by  Bichat,  but  is  reflected  inwards  upon  the  vense  Galeni 
for  a  short  distance  only,  and  returns  upon  those  vessels  to  the  dura 
mater  of  the  tentorium.  It  surrounds  the  nerves  as  they  originate 
from  the  brain,  and  forms  a  sheath  around  them  to  their  point  of 
exit  from  the  skull.  It  is  then  reflected  back  upon  the  inner  surface 
of  the  dura  mater. 

There  are  no  vessels  in  the  arachnoid,  and  no  nerves  have  been 
traced  into  it. 

Pia  Mater. 

The  Pia  mater  is  a  vascular  membrane  composed  of  innumerable 
vessels  held  together  by  a  thin  cellular  layer.  It  invests  the  whole 
surface  of  the  brain,  dipping  into  its  convolutions,  and  forming  a 
fold  in  its  interior  called  velum  inter positum.  It  also  forms  folds  in 
other  situations,  as  in  the  fourth  ventricle,  and  in  the  longitudinal 
grooves  of  the  spinal  cord. 

This  membrane  differs  very  strikingly  in  its  structure  in  different 
parts  of  the  cerebro-spinal  axis.  Thus,  on  the  surface  of  the  cere- 
brum, in  contact  with  the  soft  gray  matter  of  the  brain,  it  is  exces- 
sively vascular,  forming  remarkable  loops  of  anastomoses  between 
the  convolutions,  and  distributing  multitudes  of  minute  straight  ves- 
sels to  the  gray  substance.  In  the  substantia  perforata,  again,  and 
locus  perforatus,  it  gives  off"  tufts  of  small  arteries,  which  pierce  the 
white  matter  to  reach  the  gray  substance  in  the  interior.  But,  upon 
the  crura  cerebri,  pons  Varolii,  and  spinal  cord,  its  vascular  cha- 
racter seems  almost  lost.  It  has  become  a  dense  fibrous  membrane, 
difficult  to  tear  off,  and  forming  the  proper  sheath  of  the  spinal 
cord. 

The  pia  mater  is  the  nutrient  membrane  of  the  brain,  and  derives 
its  blood  from  the  internal  carotid  and  vertebral  arteries. 

Its  JVerves  are  the  minute  filaments  of  the  sympathetic,  which 
accompany  the  branches  of  the  arteries. 

CEREBRUM. 

The  Cerebrum  is  divided  into  two  hemispheres  by  the  great  longi- 
tudinal fissure,  which  lodges  the  falx  cerebri,  and  marks  the  original 
developement  of  the  brain  by  two  symmetrical  halves. 

Each  hemisphere,  upon  its  under  surface,  admits  of  a  division  hito 
three  lobes,  anterior,  middle,  and  posterior.  The  anterior  lobe  rests 
upon  the  roof  of  the  orbit,  and  is  separated  from  the  middle  by  the 
fissure  of  Sylvius.*     The  middle  lobe  is  received  into  the  middle 

*  Jamos  Dubois,  a  celebrated  professor  of  anatomy  in  Paris,  where  he  succeedecr 
Vidius  in  l.'j.'jf),  although  known  much  earlier  by  liis  own  works  and  discoveries,  but 
particularly  by  his  violence  in  tlio  defence  of  Galen,  His  name  was  Latinised  to 
Jacobus  Sylvius. 


CENTRUM  OVALE  MAJUS CORPUS  CALLOSUM.  367 

fossa,  in  the  base  of  the  skull,  and  is  separated  from  the  posterior  by 
a  slight  impression  produced  by  the  ridge  of  the  petrous  bone.  The 
posterior  lobe  is  supported  by  the  tentorium. 

If  the  upper  part  of  one  hemisphere  be  removed  with  a  scalpel,  a 
centre  of  white  surface  will  be  observed,  surrounded  by  a  narrow 
border  of  gray,  which  follows  the  depressions  of  the  convolutions, 
and  presents  a  zigzag  outline.  This  appearance  is  called  centrum 
ovale  minus.  The  divided  surface  will  be  seen  to  be  studded  with 
numerous  small  red  points  (puncta  vasculosa)  which  are  produced 
by  the  escape  of  blood  from  the  divided  ends  of  minute  arteries  and 
veins. 

Now  separate  carefully  the  two  hemispheres  of  the  cerebrum,  and 
a  broad  band  of  white  substance  will  be  seen  to  connect  them.  Re; 
move  the  upper  part  of  each  hemisphere,  with  a  knife,  to  a  level  with 
this  white  layer.  The  appearance  resulting  from  this  section  is  the 
centrum  ovale  majus. 

The  Centrum  ovale  majus  is  the  large  centre  of  white  substance 
presented  to  view  on  the  removal  of  the  upper  part  of  both  hemi- 
spheres ;  it  is  surrounded  by  the  thin  stratum  of  gray  substance, 
which  follows  in  a  zigzag  line  all  the  convolutions  and  the  fissures 
between  them.  In  the  middle  of  the  centrum  ovale  majus  is  the 
broad  band  which  connects  the  two  hemispheres  to  each  other,  the 
corpus  callosum. 

The  Corpus  callosum  (callosits,  hard)  is  a  dense  layer  of  transverse 
fibres  connecting  the  two  hemispheres  and  constituting  their  great 
commissure.  It  is  situated  nearer  to  the  anterior  than  to  the  poste- 
rior part  of  the  brain,  and  terminates  anteriorly  in  a  rounded  border 
which  may  be  traced  downwards  to  the  base  of  the  brain,  in  front 
of  the  commissure  of  the  optic  nerves.  Posteriorly  it  forms  a  thick 
rounded  fold  which  is  continuous  with  the  fornix. 

Beneath  the  posterior  rounded  border  of  the  corpus  callosum  is 
the  transverse  ^ssure  of  the  cerebrum,  which  extends  between  the 
hemispheres  and  crura  cerebri  from  the  fissure  of  Sylvius  on  one 
side,  to  that  on  the  opposite  side  of  the  brain.  It  is  through  this 
fissure  that  the  pia  mater  communicates  with  the  velum  interpositum. 
And  it  was  here  that  Bichat  conceived  the  arachnoid  to  enter  the 
Ventricles;  hence  it  is  also  named  the  fissure  of  Bichat. 

Along  the  middle  line  of  the  corpus  callosum  is  the  raphe,  a  linear 
depression  between  two  slightly  elevated  longitudinal  bands ;  and,  on 
either  side  of  the  raphe,  may  be  seen  the  linecB  transversce,  which 
mark  the  direction  of  the  fibres  of  which  the  corpus  callosum  is 
composed. 

If  an  incision  be  made  through  the  corpus  callosum  on  either  side 
of  the  raphe,  two  irregular  cavities  will  be  opened,  which  extend 
from  one  extremity  of  the  hemispheres  to  the  other:  these  ai'e  the 
lateral  ventricles.  To  expose  them  completely  the  upper  boundary 
should  be  removed  with  the  scissors. 

Each  Lateral  ventricle  is  divided  into  a  central  cavity,  and  three 
smaller  cavities  called  cornua.     The  anterior  cornu  curves  forwards 


368 


LATERAL  VENTRICLES. 


and  outwards  in  the  anterior  lobe ;  the  middle  cornu  descends  into 
the  middle  lobe;  and  the  posterior  cornu  passes  backwards  in  the 
posterior  lobe,  converging  towards  its  fellow  of  the  opposite  side. 
The  central  cavity  is  triangular  in  its  form,  being  bounded  above 
(roof)  by  the  corpus  callosum ;  internally  by  the  septum  lucidum, 
which  separates  it  from  the  opposite  ventricle;  and  below  {fioor)  by 
the  following  parts,  taken  in  their  order  of  position  from  before 
backwards : 

Corpus  striatum. 

Tenia  semicircularis. 

Thalamus  opticus, 

Choroid  plexus. 

Corpus  fimbriatum. 

Fornix. 

Fig.  124.* 


*  The  lateral  ventricles  of  the  cerebrum.  1,1.  T'he  two  hemispheres  cut  down  to  a 
level  with  the  corpus  callosum  so  as  to  constitute  the  centrum  ovale  majus.  The  sur- 
face is  seen  to  be  studded  witli  the  small  vascular  points — puncta  vasculosa  ;  and  sur- 
rounded by  a  narrow  margin  which  represents  the  gray  substance.  2.  A  small  portion 
of  the  anterior  extremity  of  the  corpus  callosum.  3.  Its  posterior  boundary  ;  the  inter- 
mediate portion  forming  the  roof  of  the  lateral  ventricles  has  been  removed  so  as  to 
completely  expose  those  cavities.  4.  A  part  of  the  septum  lucidum,  showing  an  inter- 
space between  its  layers — the  fifth  ventricle.  5.  The  anterior  cornu  of  one  side.  6. 
The  commencement  of  the  middle  cornu.  7.  The  posterior  cornu.  8.  The  corpus 
striatum  of  one  ventricle.  9.  The  tenia  semicircularis  covered  by  the  vena  corporis 
striata  and  tenia  Tarini.  10.  A  small  part  of  the  thalamus  opticus.  11.  The  dark 
fringe-like  body  to  the  left  of  the  figure  is  the  choroid  plexus.  This  plexus  communi- 
cates with  tliat  of  the  opposite  ventricle  through  the  foramen  of  Munro;  a  bristle  is 
passed  through  this  opening,  and  its  extremities  are  seen  resting  on  the  corpus  striatum 
at  each  side.  The  figure  ll  rests  upon  the  edge  of  the  fornix,  upon  thut  part  of  it 
which  is  called  the  corpus  fimbriatum.  12.  The  fornix.  13.  The  commencement  of 
the  hippocampus  major  descending  into  the  middle  cornu.  The  rounded  oblong  body 
in  the  posterior  cornu  of  the  lateral  ventricle,  directly  behind  the  figure  13,  is  the  hip- 
pocampus minor. 


*  CORPUS  STRIATUM CHOROID  PLEXUS.  369 

The  Corpus  striatum  is  named  from  the  striated  Hnes  of  white 
and  gray  matter  which  are  seen  upon  cutting  into  its  substance.  It 
is  gray  on  the  exterior,  and  of  a  pyriform  shape.  The  broad  end, 
directed  forwards,  rests  against  tlie  corpus  striatum  of  tlie  opposite 
side :  the  small  end,  backwards,  is  separated  from  its  fellow  by  the 
interposition  of  the  thalami  optici.  The  corpora  striata  are  the 
superior  ganglia  of  the  cerebrum. 

The  Tenia  SRinicircularis  (tenia,  a  fillet)  is  a  narrow  band  of 
medullary  substance,  extending  along  the  posterior  border  of  the 
corpus  striatum,  and  serving  as  a  bond  of  connexion  between  that 
body  and  the  thalamus  opticus.  The  tenia  is  partly  concealed  by 
a  large  vein  (vena  covporis  striali)  formed  by  small  vessels  from  the 
corpus  striatum  and  thalamus  opticus,  and  terminating  in  the  venas 
Galeni.  The  vein  is  overlaid  by  a  yellowish  band,  a  thickening  of 
the  lining  membrane  of  the  ventricle.  This  was  first  noticed  and 
described  by  Tarinus,  under  the  name  of  the  horny  band.  We  may, 
therefore,  term  it  tenia  Tarini.^ 

The  Thalamus  opticus  (thalamus,  a  bed)  is  an  oblong  body,  hav- 
ing a  thin  coating  of  white  substance  on  its  surface;  it  has  received 
its  name  from  giving  origin  to  one  root  of  the  optic  nerve.  It  is  the 
inferior  ganglion  of  the  cerebrum.  The  border  only  of  the  thalamus 
is  seen  in  the  floor  of  the  lateral  ventricle.  We  must,  therefore, 
defer  its  further  description  until  we  can  examine  it  in  its  entire 
extent. 

The  Choroid  plexus  (x^'p'"^'  ^'^'^°^'  resembling  the  chorionf)  is  a  vas- 
cular fringe  extending  obliquely  across  the  floor  of  the  lateral  ven- 
tricle, and  sinking  into  the  middle  cornu.  Anteriorly,  it  is  small  and 
tapering,  and  communicates  with  the  choroid  plexus  of  the  opposite 
ventricle,  through  a  large  oval  opening,  the  fora?nen  of  Munro.  This 
foramen  may  be  distinctly  seen  by  pulling  sHghtly  on  the  plexus, 
and  pressing  aside  the  septum  lucidum  with  the  handle  of  the  knife. 
It  is  situated  between  the  under  surface  of  the  fornix,  and  the  anterior 
extremities  of  the  thalami  optici,  and  forms  a  transverse  communi- 
cation between  the  lateral  ventricles,  and  below  with  the  third 
ventricle. 

The  choroid  plexus  is  variable  in  its  appearance,  and  sometimes 
presents  groups  and  clusters  of  small  serous  cysts,  which  have  been 
mistaken  for  hydatids. 

The  Corpus  fimbriatum  is  a  narrow  white  band,  which  is  situated 
immediately  behind  the  choroid  plexus,  and  extends  with  it  into  the 
descending  cornu  of  the  lateral  ventricle.  It  is  the  lateral  thin  edge 
of  the  fornix. 

The  Fornix  is  a  white  layer  of  medullary  substance,  of  which  a 
portion  only  is  seen  in  this  view  of  the  ventricle. 

The  .interior  cornu  is  triangular  in  its  form,  sweeping  outwards, 

*  Peter  Tarin,  a  French  anatomist:  his  work,  entitled  "  Adversaria  Anatomica,"  was 
published  in  1750. 

t  See  the  note  appended  to  the  description  of  the  choroid  coat  of  the  eyeball. 

47 


370  coRXUA  or  the  lateral  ventricles, 

and  terminating  by  a  point  in  the  anterior  lobe  of  the  brain,  at  a 
short  distance  only  from  its  surface. 

The  Posterior  cornu  or  digital  cavity  curves  inwards,  as  it  extends 
into  the  posterior  lobe  of  the  brain,  and  likewise  terminates  near  to 
the  surface.  An  elevation  corresponding  with  a  deep  sulcus  between 
two  convolutions  projects  into  the  area  of  this  cornu,  and  is  called 
the  lii-ppocampus  minor. 

The  Middle  or  descending  cornu,  in  descending  into  the  middle 
lobe  of  the  brain,  forms  a  very  considerable  curve,  and  alters  its 
direction  several  times  as  it  proceeds.  Hence  it  is  described  as 
passing  backwards  and  outwards  and  downwards,  and  then  turning 
forwards  and  inwards.  This  complex  expression  of  a  very  simple 
curve  has  given  birth  to  a  symbol  formed  by  the  primary  letters  of 
these  various  terms ;  and  by  means  of  this  the  student  recollects 
with  ease  the  course  of  the  cornu,  eodfi.  It  is  the  largest  of  the 
three  cornua. 

The  middle  cornu  should  now  be  laid  open,  by  inserting  the  little 
finger  into  its  cavity,  and  making  it  serve  as  a  director  for  the 
scalpel  in  cutting  away  the  side  of  the  hemisphere,  so  as  to  expose 
it  completely. 

Its  Superior  boundary  is  formed  by  the  under  surface  of  the  thala- 
mus opticus,  upon  which  are  the  two  projections  called  corpus 
geniculatum  internum  and  externum ;  and  the  inferior  wall  by  the 
various  parts  which  are  often  spoken  of  as  the  contents  of  the  middle 
cornu  :  these  are  the — 

Hippocampus  major. 

Pes  hippocampi. 

Pes  accessorius. 

Corpus  fimbriatum. 

Choroid  plexus, 

Fascia  dentata, 

Transverse  fissure. 

The  FIippoca?npns  major  or  coi^nu  Ammonis,  so  called  from  its  re- 
semblance to  a  ram's  horn,  the  famous  crest  of  Jupiter  Ammon,  is  a 
considerable  projection  from  the  inferior  wall,  and  extends  the  whole 
length  of  the  middle  cornu.  Its  extremity  is  likened  to  the  club-foot 
of  some  animal,  from  its  presenting  a  number  of  knuckle-like  eleva- 
tions upon  the  surface :  hence  it  is  named  pes  hippocampi.  The 
hippocampus  major  is  the  termination  of  the  lateral  edge  of  the 
hemisphere,  which  in  this  situation  is  very  much  attenuated  and 
rolled  upon  itself  If  it  be  cut  across,  the  section  will  be  seen  to  re- 
semble the  extremity  of  a  convoluted  scroll,  consisting  of  alternate 
layers  of  white  and  gray  substance.  The  hippocampus  major  is 
continuous  superiorly  with  the  fornix  and  corpus  callosum. 

The  Pes  accessorius  is  a  swelling  somewhat  resembhng  the  hippo- 
campus major,  but  smaller  in  size ;  it  is  situated  on  the  outer  wall 
of  the  cornu,  and  is  frequently  absent. 

The  Corpus  fimbriatum  is  the  narrow  white  band  which  is  pro- 


FASCIA  DEXTATA FORNIX.  371 

longed  from  the  central  cavity  of  the  ventricle,  and  is  attached  along 
the  inner  border  of  the  hippocampus  major  to  its  termination. 

Fascia  dentata: — if  the  corpus  fimbriatum  be  carefully  raised  a 
narrow  serrated  band  of  gray  substance  will  be  seen  beneath  it ; 
this  is  the  fascia  dentata. 

Beneath  the  corpus  fimbriatum  will  be  likewise  seen  the  transverse 
fissure  of  the  brain,  which  has  been  before  described  as  extending 
from  the  fissure  of  Sylvius  on  one  side,  across  to  the  same  fissure 
on  the  opposite  side  of  the  brain.  It  is  through  this  fissure  that  the 
pia  mater  communicates  with  the  choroid  plexus,  and  the  latter 
obtains  its  supply  of  blood.  The  fissure  is  bounded  on  one  side  by 
the  coi-pus  fimbriatum,  and  on  the  other  by  the  under  surface  of  the 
thalamus  opticus. 

The  internal  boundary  of  the  lateral  ventricle  is  the  septum  luci- 
dum.  This  septum  is  thin  and  semi-transparent,  and  consists  of 
two  laminse  of  cerebral  substance  attached  above  to  the  under  sur- 
face of  the  corpus  callosum  at  its  anterior  part,  and  below  to  the 
fornix.  Between  the  two  layers  is  a  narrow  space,  the  fft/i  ven- 
tricle, which  is  fined  by  a  proper  membrane.  The  ffth  ventricle 
may  be  shown,  by  snipping  through  the  septum  lucidum  transversely 
with  the  scissors. 

The  corpus  callosum  should  now  be  cut  across  towards  its  ante- 
rior extremity,  and  the  two  ends  carefully  dissected  away.  The 
anterior  portion  will  be  retained  only  by  the  septum  lucidum,  but 
the  posterior  will  be  found  incorporated  with  the  white  layer  beneath, 
which  is  the  fornix. 

The  fornix  (arch)  is  a  triangular  lamina  of  white  substance, 
broad  behind,  and  extending  into  each  lateral  ventricle:  narrow  in 
front,  where  it  terminates  in  two  crura,  which  arch  downwards  to 
the  base  of  the  brain.  The  two  crura  descend  through  the  foramen 
commune  anterius  of  the  third  ventricle,  and  terminate  in  the  cor- 
pora albicantia.  Opening  transversely  beneath  these  two  crura, 
just  as  they  are  about  to  arch  downwards,  is  the  foramen  of  Munro, 
through  which  the  two  lateral  ventricles  communicate,  and  the  cho- 
roid plexuses  are  connected  anteriorly. 

The  lateral  thin  edges  of  the  fornix  are  continuous  posteriorly 
with  the  concave  border  of  the  hippocampus  major  at  each  side, 
and  form  the  narrow  white  band  called  corpus  fimbriatum.  In  the 
middle  line  the  fornix  is  continuous  with  the  corpus  callosum,  and 
at  each  side  with  the  hippocampus  major  and  minor.  Upon  the 
under  surface  of  the  fornix  towards  its  posterior  part,  some  trans- 
verse lines  are  seen  passing  between  the  diverging  lateral  fasciculi : 
this  appearance  is  termed  the  lyra,  from  a  fancied  resemblance  to 
the  strings  of  a  harp. 

The  fornix  may  now  be  removed  by  dividing  it  across  anteriorly, 
and  turning  it  backwards,  at  the  same  time  separating  its  lateral 
connexions  with  the  hippocampi.  If  the  student  examine  its  under 
surface,  he  will  perceive  the  lyra  above  described. 

Beneath  the  fornix  is  the  velum  interpositum,  a  rcfiection  of  pia 
mater  introduced  into  the  interior  of  the  brain,  throucjh  the  trons- 


372 


THALAMI  OPTICI. 


verse  fissure.  The  velum  is  connected  at  each  side  with  the  choroid 
plexus,  and  contains  within  its  two  layers,  in  the  middle  line,  two 
large  veins,  the  vencE  Galeni,  which  receive  the  blood  from  the 
ventricles,  and  terminate  posteriorly  in  the  straight  sinus.  Upon 
the  under  surface  of  the  velum  interpositum  are  two  fringe-like 
bodies  which  project  into  the  third  ventricle.  These  are  the  choroid 
plexuses  of  the  third  ventricle. 

Fig.  125.* 


If  the  velum  interpositum  be  raised  and  turned  back,  an  operation 
which  must  be  conducted  with  care,  particularly  at  its  posterior  part, 
where  it  invests  the  pineal  gland,  the  thalami  optici  and  the  cavity 
of  the  third  ventricle  will  be  brought  into  view. 

The  Thalami  optici  are  two  rounded  oblong  bodies,  of  a  white 
colour  superficially,  inserted  between  the  two  diverging  portions  of 
the  corpora  striata.  In  the  middle  line  a  fissure  exists  between 
them,  which  is  called  the  third  ventricle.  Posteriorly  and  inferiorly, 
they  form  the  superior  wall  of  the  descending  cornu,  and  present 

*  The  mesial  surface  of  a  longitudinal  section  of  the  brain.  The  incision  has  been 
carried  along  the  middle  line ;  between  the  two  liemispheres  of  the  cerebrum,  and 
through  the  middle  of  the  cerebellum  and  medulla  oblongata.  1.  The  inner  surface  of 
the  left  hemisphere.  2.  The  divided  surface  of  the  cerebellum,  showing  the  arbor  vitee. 
3.  The  medulla  oblongata.  4,  The  corpus  callosum,  rounded  before  to  terminate  in 
the  base  of  the  brain  ;  and  behind,  to  become  continuous  with  5,  the  fornix.  6.  One 
of  the  crura  of  the  fornix  descending  to  7,  one  of  the  corpora  albicantia.  8.  The 
septum  lucidum.  9.  The  velum  interpositum,  communicating  with  tlie  pia  mater  of  the 
convolutions  through  the  fissure  of  Bichat.  10.  Section  of  the  middle  commissure 
situated  in  the  third  ventricle.  11.  Section  of  tlio  anterior  commissure.  12.  Section 
of  the  posterior  commissure;  the  commissure  is  somewhat  above  and  to  the  left  of  the 
number.  The  interspace  between  10  and  11  is  the  foramen  commune  anterius,  in 
which  the  crus  of  the  fornix  (6)  is  situated.  The  interspace  between  10  and  12  is  the 
foramen  commune  postcrius.  13.  The  corpora  quadrigemina,  upon  which  is  seen 
resting  (he  pineal  gland,  14.  1.5.  The  iter  e  tcrtio  ad  quartum  vcntriculum.  IG.  The 
fourth  ventricle.  17.  The  pons  Varolii,  through  which  arc  seen  passing  the  diverging 
fibres  of  the  corpora  pyramidalia.  18.  The  crus  cerebri  of  the  left  side,  with  the  third 
nerve  arising  from  it.  19.  The  tuber  cinercum,  from  which  projects  the  infundibulum 
having  the  pituitary  gland  appended  to  its  extremity.  20.  One  of  the  optic  nerves.  21. 
The  left  olfactory  nerve  terminating  anteriorly  in  a  rounded  bulb. 


THIRD  VENTRICLE.  373 

two  rounded  elevations  called  corpus  geniculatum  externum  and 
internum.  The  corpus  geniculatum  externum  is  the  larger  of  the 
two,  and  of  a  grayish  colour ;  it  is  the  principal  origin  of  the  optic 
nerve.  Inferiorly,  the  thalami  are  connected  with  the  corpora  albi- 
cantia  by  means  of  two  white  bands,  w^hich  appear  to  originate  in 
the  white  substance  uniting  the  thalami  to  the  corpora  striata.  In 
their  interior  the  thalami  are  composed  of  white  fibres  mixed  with 
gray  substance.  They  are  essentially  the  inferior  ganglia  of  the 
cerebrum. 

The  Third  ventricle  is  the  fissure  between  the  two  thalami  optici. 
It  is  bounded  above  by  the  under  surface  of  the  velum  interpositum, 
from  which  are  suspended  the  choroid  plexuses  of  the  third  ventricle. 
lis,  floor  is  formed  by  the  anterior  termination  of  the  corpus  callosum, 
the  tuber  cinereum,  corpora  albicantia,  and  locus  perforatus.  Late- 
rally it  is  bounded  by  the  thalami  optici  and  part  of  the  corpora 
striata;  anteriorly  by  the  anterior  commissure  and  crura  of  the 
fornix ;  and  posteriorly  by  the  posterior  commissure  and  the  iter  e  " 
tertio  ad  quartum  ventriculum. 

The  third  ventricle  is  crossed  by  three  commissures,  the  anterior, 
middle,  and  posterior ;  and  between  these  are  two  spaces,  called 
foramen  commune  anterius  and  foramen  commune  posterius. 

The  Anterior  commissure  is  a  rounded  white  cord,  which  enters 
the  corpus  striatum  at  either  side ;  the  middle,  or  soft  commissure 
consists  of  gray  matter,  and  is  very  easily  broken  down ;  it  connects 
the  adjacent  sides  of  the  thalami  optici :  and  the  posterior  commis- 
sure is  a  flattened  white  cord,  connecting  the  two  thalami  optici 
posteriorly. 

Between  the  anterior  and  middle  commissure  is  the  space  called 
foramen  commune  anterius,  which,  from  leading  downwards  into  the 
infundibulum,  is  also  designated  iter  ad  infundihulum.  The  crura 
of  the  fornix  descend  through  this  space,  surrounded  by  gray  matter, 
to  the  corpora  albicantia.  Betw^een  the  middle  and  posterior  com- 
missure is  the  foramen  cominune  posterius,  from  which  a  canal  leads 
backwards  to  the  fourth  ventricle,  the  iter  a  tertio  ad  quartum  ventn- 
culum. 

Behind  the  third  ventricle  is  placed  the  quadrifid  ganglion,  called 
optic  lobes  in  the  inferior  animals,  and  corpora  quadrigemina  in  man. 
The  two  anterior  of  these  bodies  are  the  larger,  and  are  named 
nates;  the  two  posterior,  testes.  Their  base  is  perforated  from 
before  backwards  by  a  tubular  canal,  which  serves  to  communicate 
the  third  and  fourth  ventricles,  and  is  thence  named  the  iter  e  tertio 
ad  quartum  ventriculum,  or  aqueduct  of  Sylvius.  Resting  upon  the 
corpora  quadrigemina  and  surrounded  by  a  sheath  of  pia  mater, 
obtained  from  the  velum  interpositum,  with  which  it  is  liable  to  be 
torn  oft'  unless  very  great  care  be  used,  is  the  pineal  gland. 

The  Pineal  gland  consists  of  soft  gray  substance,  and  is  of  a 
conical  form  ;  hence  one  of  its  synonymes,  conarinm.  It  contains 
in  its  interior  several  brov/nish  granules,  which  are  composed  of 
phosphate  and  carbonate  of  lime.     It  is  connected  to  the  thalami 


374  CHOROID  PLEXUSES. 

optici  by  two  small  rounded  cords,  called  peduncles,  and  is  very  im- 
properly called  a  gland. 

Behind  the  corpora  quadrigemina  is  the  cerebellum,  and  beneath 
the  cerebellum  the  fourth  ventricle.  The  student  must  therefore 
divide  the  cerebellum  down  to  the  fourth  ventricle,  and  turn  its  lobes 
aside  to  examine  that  cavity. 

The  Fourth  ventricle  is  the  ventricle  of  the  medulla  oblongata, 
upon  the  posterior  surface  of  which  it  is  placed.  It  is  an  oblong 
quadrilateral  cavity,  hounded  on  each  side  by  a  thick  cord  passing 
between  the  cerebellum  and  corpora  quadrigemina,  called  the  p?'o- 
cessiis  e  cerebello  ad  testes,  and  by  the  corfiLS  restiforme.  It  is  covered 
in  behind  by  the  arch  of  the  cerebellum,  which  forms  three  remarka- 
ble projections  into  its  cavity,  named,  from  their  resemblance,  uvula 
and  tonsils:  and  by  a  thin  lamella  of  white  substance,  stretched 
between  the  two  processus  e  cerebello  ad  testes,  termed  the  valve  of 
Fieussens.*  This  layer  is  easily  broken  down,  and  requires  that 
care  be  used  in  its  demonstration.  In  fj-ont  the  fourth  ventricle  is 
bounded  by  the  posterior  surface  of  the  medulla  oblongata ;  above 
by  the  corpora  quadrigemina,  and  the  termination  of  the  iter  e  tertio 
ad  quartum  ventriculum ;  and  beloiv  by  a  layer  of  pia  mater  and  one 
of  arachnoid,  passing  between  the  under  surface  of  the  cerebellum 
and  the  medulla  oblongata,  called  the  valve  of  the  arachnoid. 

We  observe  within  the  fourth  ventricle  the  chm-oid  plexuses,  the 
calamus  scriptorius,  and  the  linece  transverscB. 

The  Choriod  plexuses  resemble  in  miniature  those  of  the  lateral 
ventricles  :  they  are  formed  by  the  pia  mater,  and  lie  against  that 
part  of  the  cerebellum  called  uvula  and  tonsils. 

The  anterior  wall,  or  floor,  of  the  fourth  ventricle  is  formed  of 
gray  substance,  which  is  continuous  with  that  contained  within  the 
spinal  cord.  This  gray  substance  is  separated  into  two  bands  by 
a  median  fissure,  which  is  continuous  with  the  calamus  scriptorius. 
The  two  bands  are  considered  by  Mr.  Solly  as  the  two  posterior 
pyramids ;  and  he  has  observed  in  their  structure  such  an  arrange- 
ment of  fibres  as  induces  him  to  name  them  the  "  posterior  ganglia 
of  the  medulla  oblongata,"  in  opposition  to  the  corpora  oKvaria,  which 
he  describes  as  the  "  anterior  ganglia  of  the  medulla" 

The  Calamus  scriptorius  is  a  groove  upon  the  anterior  wall,  or 
floor,  of  the  fourth  ventricle.  Its  pen-like  appearance  is  produced 
by  the  divergence  of  the  posterior  median  columns,  the  feather  by 
the  lincoe  transversse.  At  the  point  of  the  pen  is  a  small  cavity  lined 
with  gray  substance,  and  called  the  ventricle  of  Arantius. 

The  Linece  transversa;  are  irregular  transverse  lines  upon  the  an- 
terior wall  of  the  ventricle,  which  in  some  degree  resemble  the 
plume  of  the  pen.  They  are  the  filaments  of  origin  of  the  auditory 
nerve. 

The  existence  of  a  communication  between  the  fourth  ventricle 

*  Raymond  Viousscns,  a  gniat,  fllscovnrcr  in  tlio  nnatomy  of  the  brain  nnd  ncrvouf" 
Bystcin.     His  "  Ncurograpliia  Universalis"  was  puljlishcd  at  Lyons,  in  1G85. 


LINING  MEMBRANE  OF  THE  VENTRICLES.  375 

and  the  subarachnoidean  space,  as  imagined  by  Magendie,  is  very 
questionable. 

LINING  MEMBRANE  OF  THE  VENTRICLES. 

The  lining  membrane  of  the  ventricles  is  a  serous  layer,  quite 
distinct  from  the  arachnoid,  and  having  no  communication  with  it. 
This  membrane  lines  the  whole  of  the  interior  of  the  lateral  ventri- 
cles, and  is  connected  above  and  below  to  the  attached  border  of 
the  choroid  plexus,  so  as  to  exclude  completely  all  communication 
between  the  ventricles  and  the  exterior  of  the  brain.  It  is  reflected 
through  the  foramen  of  Munro,  on  each  side,  into  the  third  ventricle, 
which  it  invests  throughout.  From  the  third  it  is  conducted  into 
the  fourth  ventricle,  through  the  iter  e  tertio  ad  quartum  ventri- 
culum,  and  lines  its  interior,  together  with  the  layer  of  pia  mater 
which  forms  its  inferior  boundary.  In  this  manner  a  perfect  com- 
munication is  established  between  all  the  ventricles.  It  is  this 
membrane  which  gives  them  their  polished  surface,  and  transudes 
the  secretion  which  moistens  their  interior.  When  the  fluid  accu- 
mulates to  an  unnatural  degree,  it  may  then  break  down  this  layer 
and  the  layer  of  pia  mater  at  the  bottom  of  the  fourth  ventricle, 
and  thus  make  its  way  into  the  subarachnoidean  cellular  tissue ; 
but  in  the  normal  condition  it  is  doubtful  whether  a  communication 
exists  between  the  interior  of  the  ventricles  and  the  cavity  of  the 
subarachnoidean  space. 

CEREBELLUM. 

The  Cerebellum,  according  to  Cruveilhier,  is  seven  times  smaller 
than  the  cerebrum.  Like  that  organ,  it  is  composed  of  white  and 
gray  substance,  whereof  the  gray  is  larger  in  proportion  than  the 
white.  Its  surface  is  formed  by  parallel  lamellcB,  separated  by 
fissures  ;  and  at  intervals  deeper  fissures  exist,  which  divide  it  into 
larger  segments  termed  lobules.  The  cerebellum  is  divided  into 
two  lateral  hemispheres  or  lobes,  two  minor  lobes  called  superior 
and  inferior  vermiform  processes,  and  some  small  lobules. 

The  Lateral  lobes  are  separated  from  each  other  posteriorly  by 
a  depression  which  lodges  the  falx  cerebelli,  and  above  and  below 
by  the  projection  of  the  vermiform  processes. 

The  Superior  vermiform,  process,  a  slightly  elevated  ridge  along 
the  middle  of  the  upper  surface  of  the  cerebellum,  is  all  that  exists 
of  that  organ  in  birds,  and  it  constitutes  the  largest  proportion  of 
the  cerebellum  in  many  mammalia.  It  is  situated  along  the  middle 
line,  and  serves  to  connect  the  lateral  lobes  superiorly. 

The  Inferior  vermiform  process  forms  a  projection  inferiorly,  and 
is  the  means  of  connexion  between  the  lateral  lobes  below. 

The  principal  lobules  are  the  pneumogastric,  the  tonsils,  uvula, 
and  linguetta  laminosa. 


376  CEREBELLUM. 

The  Pneumogastric  lobule  (flocculus)  is  situated  on  the  anterior 
border  of  the  cerebellum,  near  to  the  origin  of  the  eighth  pair  of 
nerves,  and  is  hence  called  pneumogastric.  It  is  not  unUke  a  con- 
voluted- shell  in  its  form. 

The  Tonsils  and  uvula  resemble  those  organs  in  a  swollen  state 
very  strikingly ;  they  project  from  the  under  surface  of  the  cere- 
bellum into  the  fourth  ventricle. 

The  Lingueila  iaminosa  is  a  thin  tonguelet  of  gray  substance, 
marked  by  transverse  furrows,  which  extend  forwards  upon  the 
valve  of  Vieussens  from  the  gray  substance  of  the  cerebellum. 

When  cut  into  vertically,  the  cerebellum  presents  the  appearance 
termed  arbor  vita.  If  the  incision  be  made  throuo-h  the  outer  third 
of  the  organ,  a  gray  body,  surrounded  by  a  yellow  zigzag  line  of 
horny  structure,  will  be  seen  in  the  centre  of  the  white  substance : 
this  is  the  corpus  rhomboideum,  or  ganglion  of  the  cerebellum. 

The  cerebellum  is  associated  with  the  spinal  cord  and  cerebrum 
by  thiee  pairs  of  peduncles ;  the 

Corpora  restiformia, 
Processus  e  cerebello  ad  testes. 
Crura  cerebelli. 

The  Corpora  restiformia,  or  inferior  peduncles,  diverge  at  the 
upper  extremity  of  the  medulla  oblongata,  and  enter  the  cerebellum, 
forming,  by  their  divergence,  part  of  the  lateral  boundaries  of  the 
fourth  ventricle.  Their  fibres  surround  the  corpus  rhomboideum, 
and  are  expanded  into  the  lamellae  of  the  cerebellum. 

The  Processus  e  cerebello  ad  testes  are  the  superior  peduncles : 
they  ascend  from  the  corpus  rhomboideum,  on  each  side,  to  the 
testis,  and  also  form  a  part  of  the  lateral  boundaries  of  the  fourth 
ventricle.  The  valve  of  Vieussens,  by  connecting  the  two  pro- 
cessus e  cerebello  ad  testes  from  side  to  side,  and  the  cerebellum 
and  testes  from  behind  forwards,  also  contributes  to  the  antero-pos- 
terior  communication  of  the  cerebellum. 

The  Crura  cerebelli  are  the  terminations  of  the  transverse  fibres 
of  the  pons  Varolii,  or  great  commissure  of  the  cerebellum,  which 
serves  to  establish  a  transverse  communication  between  the  lateral 
lobes. 

BASE  OF  THE  BRAIN. 

The  student  should  now  prepare  to  study  the  base  of  the  brain : 
for  this  purpose  the  organ  should  be  turned  upon  its  incised  surface; 
and  if  the  dissection  have  hitherto  been  conducted  with  care,  he 
will  find  the  base  perfectly  uninjured.  The  arachnoid  membrane, 
some  parts  of  the  pia  mater,  and  the  circle  of  Willis,  must  be  care- 
fully cleared  away  in  order  to  expose  all  the  structures.  These  he 
will  find  arranged  in  the  following  order  from  before  back- 
wards:— 


BASE  OF  THE  BRAIN.  577 

Longitudinal  fissure, 

Olfactory  nerves, 

Fissure  of  Sylvius, 

Substantia  perforata, 

Commencement  of  the  transverse  fissure, 

Optic  commissure, 

Tuber  cinereum, 

Infundibulum, 

Corpora  albicantia, 

Locus  perforatus, 

Crura  cerebri, 

Pons  Varolii, 

Crura  cerebelli. 

Medulla  oblongata. 

The  Longitudinal  fissure  is  the  space  separating  the  two  hemi- 
spheres: it  is  continued  downwards  to  the  base  of  the  brain,  and 
divides  the  two  anterior  lobes.  In  this  fissure  the  anterior  cerebral 
arteries  ascend  towards  the  corpus  callosum;  and,  if  the  two  lobes 
be  slightly  drawn  asunder,  the  anterior  extremity  of  the  corpus  cal- 
losum will  be  seen  descending  to  the  base  of  the  brain. 

On  each  side  of  the  longitudinal  fissure,  upon  the  under  surface  of 
each  anterior  lobe,  is  the  olfactojy  nerve,  with  its  bulb. 

The  Fissure  of  Sylvius  bounds  the  anterior  lobe  posteriorly,  and 
separates  it  from  the  middle  lobe;  it  lodges  the  middle  cerebral 
artery.  If  this  fissure  be  followed  outwards,  a  small  isolated  cluster 
of  convolutions  will  be  observed;  these  constitute  the  island  of  Reil. 

The  Substantia  perforata  is  a  triangular  plane  of  white  substance, 
situated  at  the  inner  extremity  of  the  fissure  of  Sylvius.  It  is  named 
perforata,  from  being  pierced  by  a  number  of  openings  for  small 
arteries,  v/hich  enter  the  brain  in  this  situation  to  supply  the  gray 
substance  of  the  corpus  striatum. 

Passing  backwards  on  each  side  beneath  the  edge  of  the  middle 
lobe,  is  the  commencement  of  the  great  transverse  fissure,  which 
extends  beneath  the  hemisphere  of  one  side  to  the  same  point  on  the 
opposite  side. 

The  Optic  commissure  is  situated  on  the  middle  line ;  it  is  the  point 
of  communication  between  the  two  optic  nerves. 

The  Tuher  cinereum  is  an  eminence  of  gray  substance  immediately 
behind  the  optic  commissure,  and  connected  with  its  posterior  bor- 
der.    It  forms  part  of  the  floor  of  the  third  ventricle. 

The  Infundibulum  is  a  tubular  process  of  gray  substance,  opening 
from  the  centre  of  the  tuber  cinereum,  and  attached  below  to  the 
pituitary  gland,  which  is  lodged  in  the  sella  turcica.  This  gland  is 
retained  within  the  sella  turcica  by  the  dura  mater  and  arachnoid, 
and  is  with  great  difficulty  removed  with  the  brain.  It  is,  therefore, 
better  left  in  its  place,  where  it  is  intended  to  study  afterwards  the 
base  of  the  skull ;    for  any  attempt  at  removal  would  injure  the 

48 


378  BASE  OF  THE  BRAIN. 

cavernous  sinuses.  It  consists  of  two  lobes,  but  presents  nothing 
glandular,  either  in  structure  or  function. 

-The  Corpora  albicantia  are  two  rounded  white  bodies,  placed  side 
by  side,  of  about  the  size  of  peas;  hence  their  synonyme,  fisiformia. 
They  are  the  anterior  extremities  of  the  crura  of  ihe  fornix,  and  are 
connected  with  the  thalami  optici  by  two  white  cords,  which  may 
be  easily  traced. 

The  Locus  perforatus  is  a  layer  of  whitish  gray  substance,  con- 
nected in  front  with  the  corpora  albicantia,  and  on  each  side  with 
the  crura  cerebri,  between  which  it  is  situated.  It  is  perforated  by 
several  thick  tufts  of  arteries,  which  are  distributed  to  the  thalami 
optici  and  third  ventricle,  of  which  it  assists  in  forming  the  floor.  It 
is  sometimes  called  the  pons  Tarini. 

The  Crura  cerebri  are  two  thick  white  cords  which  issue  from 
beneath  the  pons  Varolii,  and  diverge  to  each  side  to  enter  the  tha- 
lami optici.  The  third  nerve  will  be  observed  to  arise  from  the  inner 
side  of  each,  and  the  fourth  nerves  wind  around  them  from  above. 
If  the  crus  cerebri  be  cut  across,  it  will  be  seen  to  present,  in  the 
centre  of  the  section,  the  locus  niger. 

The  Pons  Varolii*  (protuberantia  annularis)  is  the  broad  transverse 
band  of  white  fibres,  which  arches  like  a  bridge  across  the  upper 
part  of  the  medulla  oblongata ;  and,  contracting  on  each  side  into  a 
thick  rounded  cord,  enters  the  substance  of  the  cerebellum  under 
the  name  of  crus  cerebelli.  There  is  a  groove  along  its  middle 
which  lodges  the  basilar  artery.  The  pons  Varolii  is  the  commis- 
sure of  the  cerebellum,  and  associates  the  two  lateral  lobes  in  their 
common  function.  Resting  upon  the  pons,  near  its  posterior  border, 
is  the  sixth  pair  of  nerves.  On  the  anterior  border  of  the  crus  cere- 
belli, at  each  side,  is  the  thick  bundle  of  filaments  belonging  to  the 
fifth  nerve,  and,  lying  on  its  posterior  border,  the  seventh  pair  of 
nerves. 

The  Medulla  oblongata  is  the  upper  enlarged  portion  of  the  spinal 
cord.  Upon  its  anterior  surface  are  seen  two  narrow  projecting 
columns,  the  corpora  pyramidalia.  These  bodies  are  broad  above, 
and  narrow  below;  and,  at  the  point  where  they  enter  the  pons  Va- 
rolii, they  become  considerably  constricted.  They  are  connected  to 
each  other  in  the  middle  fissure,  at  about  an  inch  below  the  pons, 
by  a  decussation  of  their  fibres,  which  form  small  interlacing  bands 
crossing  from  side  to  side. 

Externally  to  the  corpora  pyramidalia  are  two  oblong  and  rounded 
bodies,  supposed  to  resemble  olives  in  their  form,  and  hence  called 
corpora  olivaria.  If  these  bodies  be  divided  by  a  longitudinal  sec- 
tion, a  gray  zigzag  outline,  resembling  the  corpus  rhomboideum  of 

*  Constant  Varolius,  Professor  of  Anatomy  in  Bolog'na  :  died  in  1578.  He  dissected 
the  brain  in  the  course  of  its  fibres,  beginninjr  from  tlic  medulla  oblongata:  a  plan 
which  has  since  been  perfected  by  Vieussens,  and  by  Gall  and  Spurzheim.  The  work 
containing  his  mode  of  dissection,  "  De  Resolutione  Corporis  Humani,"  was  published 
after  his  death,  in  1591. 


MEDULLA  OBLONGATA. 


379 


the  cerebellum,  will  be  seen  in  the  interior  of  each.     This  is  the 
ganghon  of  the  corpus  olivare. 

Behind  the  corpus  olivare  is  a  narrow  white  band,  which  de- 
scends along  the  side  of  the  medulla  oblongata  at  the  bottom  of  the 
lateral  sulcus.  This  is  the  situation  of  the  respiratory  tract  of  Sir 
Charles  Bell. 

Fig-.  126* 


The  Corpora  restiformia  (restis,  a  rope)  are  the  remaining 
columns,  of  the  medulla  oblongata;  they  form  its  posterior  segment, 
and  diverge  superiorly  to  enter  the  cerebellum.  Between  the  two 
corpora  restiformia  posteriorly  are  two  other  white  bands,  which 
diverge  at  the  point  of  the  calamus  scriptorius,  and  join  the  cor- 


*  The  under  surface  or  base  of  the  brain.  1.  The  anterior  lobe  of  one  hemisphere 
of  the  cerebrum.  2.  The  middle  lobe.  3.  The  posterior  lobe  almost  concealed  by  (4) 
the  lateral  lobe  of  the  cerebellum.  5.  The  inferior  vermiform  process  of  the  cerebellum. 
6.  The  pneumogastric  lobule.  7.  The  long-itudinal  fissure.  8.  The  olfactory  nerves, 
with  their  bulbous  expansions.  9.  The  substantia  perforata  at  the  inner  termination 
of  the  fissure  of  Sylvius  ;  the  three  roots  of  the  olfactory  nerve  arc  seen  upon  the  sub- 
stantia perforata.  The  commencement  of  the  transverse  fissure  on  each  side  is  con- 
cealed by  the  inner  border  of  the  middle  lobe.  10.  The  commissure  of  the  optic  nerves. 
11.  The  tuber  cinereum,  from  which  the  infundibulum  is  seen  projecting-.  12.  The 
corpora  albicantia.  13.  The  locus  perforatus  bounded  on  each  side  by  the  crura  cere- 
bri, and  by  the  third  nerve.  14.  The  pons  Varolii.  15.  Tlie  crus  cerebelli  of  one  side. 
16.  The  fifth  nerve  emerging-  from  the  anterior  border  of  the  crus  cerebelli ;  the  small 
nerve  by  its  side  is  the  fourth.  17.  The  sixth  pair  of  nerves.  18.  The  seventh  pair 
of  nerves  consisting  of  the  auditory  and  facial.  19.  The  corpora  pyramidalia  of  the 
medulla  oblongata ;  the  corpus  olivare  and  part  of  the  corpus  restiforme  are  seen  at 
each  side.  Just  below  the  number  is  the  decussation  of  the  fibres  of  the  corpora  pyra- 
mydalia.  20.  The  eighth  pair  of  nerves.  21.  The  ninth  or  hypoglossal  nerve.  22. 
The  anterior  root  of  the  first  cervical  spinal  nerve. 


380 


FIBRES  OF  THE  BRAIN, 


pora  restiformia :  these  are  the  posterior  median  fasciculi  of  the 
medulla  oblongata. 

If  a  thin  layer  of  the  pons  Varolii  be  carefully  raised,  or  if  a  lon- 
gitudinal incision  be  made  across  it,  it  may  easily  be  seen  that  the 
corpus  pyramidale  passes  through  the  pons  into  the  crus  cerebri. 
If  the  crus  cerebri  be  traced  forwards,  it  will  be  found  to  enter  the 
thalamus  opticus,  and  leaving  it  by  the  opposite  border  to  plunge 
into  the  corpus  striatum,  and  pass  from  thence  onwards  to  the  con- 
volutions of  the  hemispheres. 

Fig.  127.* 


From  pursuing  this  remarkable  course,  and  spreading  out  as  they 
advance,  these  fibres  have  been  called  by  Gall  the  diverging  fibres. 
While  situated  within  the  pons  it  is  found  that  the  fibres  of  the  cor- 
pus pyramidale  separate  and  spread  out,  and  have  gray  substance 

*  The  base  of  the  brain,  upon  which  several  sections  have  been  made,  showing  the 
distribution  of  the  diverging  fibres.  1.  The  medulla  oblongata.  2.  One  half  of  the 
pons  Varolii.  .3,  The  crus  cerebri  crossed  by  the  optic  nerve  (4),  and  spreading  out 
into  the  substance  of  the  middle  lobe.  5.  The  two  roots  of  the  optic  nerve ;  the  nerves 
about  the  crus  cerebri  and  cerebclli  are  the  same  as  in  the  preceding  figure.  6.  The 
olfactory  nerve.  7.  The  corpora  albicantia.  On  the  right  side  a  portion  of  the  brain 
has  been  removed  to  show  the  distribution  of  the  diverging  fibres.  8.  The  fibres  of  the 
corpus  pyramidale  passing  through  fhc  substance  of  the  pons  Varolii.  9.  The  fibres 
passing  through  the  thalamus  opticus.  10.  The  fibres  passing  through  the  corpus 
striatum.  11.  Their  distribution  to  the  hemispheres.  12.  The  fifth  nerve;  its  two 
roots  may  be  traced,  the  one  forwards  to  the  fibres  of  the  corpus  pyramidale,  the  other 
backwards  to  the  corpus  restiforme.  13.  The  fibres  of  the  corpus  pyramidale  which 
pass  outwards  with  the  corpus  restiforme  into  the  substance  of  the  cerebellum  ;  these 
are  the  arciform  fibres  of  Solly.  The  number  rests  upon  the  upper  part  of  the  corpus 
olivarc  ;  the  rest  of  that  body  having  been  cut  away,  the  arciform  fibres  are  below  the 
number.  14.  A  section  through  one  of  the  lateral  lobes  of  the  cerebellum,  showing  the 
corpus  rhomboideum  in  the  centre  of  its  white  substance;  the  arbor  vita)  is  also  beauti- 
fully seen,     15.  The  opposite  lobe  of  the  cerebellum. 


DIVERGING  FIBRES.  381 

interposed  between  them ;  and  that  they  quit  the  pons  much  increased 
in  number  and  bulk,  so  as  to  form  the  cms  cerebri.  The  fibres  of 
the  crus  cerebri  again  are  separated  in  the  thalamus  opticus,  and 
are  intermingled  with  gray  matter,  and  they  also  quit  that  body 
greatly  increased  in  number  and  bulk.  Precisely  the  same  change 
takes  place  in  the  corpus  striatum,  and  the  fibres  are  now  so  extra- 
ordinarily multiphed  as  to  be  capable  of  forming  a  large  proportion 
of  the  hemispheres,  viz.,  the  whole  of  the  lower  part  of  the  anterior 
and  middle  lobes. 

From  observing  this  remarkable  increase  in  the  white  fibres, 
apparently  from  the  admixture  of  gray  substance.  Gall  and  Spurz- 
heim  considered  the  latter  as  the  material  increase  of  formative 
substance  to  the  white  fibres,  and  they  are  borne  out  in  this  conclu- 
sion by  several  collateral  facts,  among  the  most  prominent  of  which 
is  the  great  vascularity  of  the  gray  substance ;  and  the  larger  pro- 
portion of  the  nutrient  fluid  circulating  through  it,  is  fully  capable 
of  effecting  the  increased  growth  and  nutrition  of  the  structures  by 
which  it  is  surrounded.  For  a  like  reason  the  bodies  in  which  this 
gray  substance  occurs,  are  called  by  the  same  physiologists  ^^ ganglia 
of  increase"  and  by  other  authors  simply  ganglia.  Thus  the 
thalami  optici  and  corpora  striata  are  the  ganglia  of  the  cerebrum ; 
or,  in  other  words,  the  formative  ganglia  of  the  hemispheres. 

Mr.  Solly,  in  a  recent  work  upon  "  the  human  brain,"  has  desig- 
nated the  diverging  fibres  of  the  corpus  pyramidale  that  pursue  the 
course  above  described,  "  the  cerebral  fibres ;"  to  distinguish  them 
from  another  set  of  fibres  discovered  by  that  gentleman,  which  also 
proceed  from  the  corpus  pyramidale,  and  pass  outwards  beneath  the 
corpus  olivare  to  the  cerebellum.  These  he  names  the  "  arciform 
fibres,"  and  divides  them  into  two  layers,  the  superficial  cerebellar 
and  deep  cerebellar  fibres.  They  join  the  corpus  restiforme,  forming 
one-fourth  of  its  whole  diameter,  and  spread  out  in  the  structure  of 
the  cerebellum. 

The  Corpora  olivaria  owe  their  convex  olive-shaped  form  to  a 
"ganglion  of  increase"  (the  anterior  ganglia  of  the  medulla  oblongata 
of  Solly),  situated  in  the  interior  of  each. 

The  white  fibres  surrounding  these  ganglia  form  a  fasciculus  at 
each  side,  which  is  continued  into  the  pons  Varolii  along  with  the 
corpora  pyramidalia.  Here  its  fibres  are  mixed  with  gray  matter, 
and  pass  into  the  crus  cerebri,  forming  its  superior  and  inner  seg- 
ment. From  the  crus  cerebri  they  traverse  successively  the  thalamus 
opticus  and  corpus  striatum,  and  become  developed  into  the  convolu- 
tions of  the  upper  part  of  the  hemispheres  and  posterior  lobe. 

The  Corpora  restiformia  diverge  as  they  approach  the  cerebellum, 
and  leaving  between  them  the  cavity  of  the  fourth  ventricle  enter 
the  substance  of  the  cerebellum,  under  the  form  of  two  rounded 
cords.  These  cords  envelope  the  coi-pora  rhomboidea,  or  ganglia 
of  increase,  and  then  expand  on  all  sides  so  as  to  constitute  the 
cerebellum. 

In  addition  to  the  diverging  fibres  which  are  thus  shown  to  con- 


382  CONVERGING  FIBRES. 

stitute  both  the  cerebrum  and  cerebellum,  by  then"  increase  and 
developement,  another  set  of  fibres  are  found  to  exist,  which  have 
for  their  otfice  the  association  of  the  symmetrical  halves,  and  distant 
parts  of -the  same  hemispheres. 

These  are  called  from  their  direction  converging  jihres,  and  from 
their  office  commissures.  The  commissures  of  the  cerebrum  and 
cerebellum  are  the — 

Corpus  callosum, 
Fornix, 

Septum  lucidum, 
Anterior  commissure, 
Middle  commissure, 
Posterior  commissure. 
Peduncles  of  the  pineal  gland, 
Processus  e  cerebello  ad  testes, 
Valve  of  Vieussens, 
Pons  Varolii. 

The  Corpus  callosum  is  the  commissure  of  the  hemispheres.  It  is 
therefore  of  moderate  thickness  in  the  middle,  where  its  fibres  pass 
directly  from  one  hemisphere  to  the  other ;  thicker  in  front,  where 
the  anterior  lobes  are  connected ;  and  thickest  behind,  where  the 
fibres  from  the  posterior  lobes  are  assembled. 

The  Fornix  is  an  antero-posterior  commissure,  and  serves  to  con- 
nect a  number  of  parts.  Below  it  is  associated  with  the  thalami 
optici ;  on  each  side,  by  means  of  the  corpora  fimbriata,  with  the 
middle  lobes  of  the  brain ;  and,  above,  with  the  corpus  callosum, 
and  consequently  with  the  hemispheres. 

The  Septum  lucidum  is  a  perpendicular  commissure  between  the 
fornix  and  corpus  callosum. 

The  Anterior  commissure  traverses  the  corpus  striatum,  and  con- 
nects the  anterior  and  middle  lobes  of  opposite  hemispheres. 

The  Middle  commissure  is  a  layer  of  gray  substance,  uniting  the 
thalami  optici. 

The  Posterior  commissure  is  a  white  flattened  cord,  connecting  the 
thalami  optici. 

The  Peduncles  of  the  pineal  gland  must  also  be  regarded  as  com- 
missures, assisted  in  their  function  by  the  gray  substance  of  the 
gland. 

The  Processus  e  cerebello  ad  testes  are  the  means  of  communica- 
tion between  the  white  substance  of  the  cerebellum  and  cerebrum  ; 
and  the  linguetta  laminosa  and  valve  of  Vieussens  perform  the  same 
office  to  the  gray  substance. 

The  Pons  Varolii  is  the  commissure  to  the  two  lobes  of  the  cere- 
bellum. It  consists  of  transverse  fibres,  which  are  split  into  two 
layers  by  the  passage  of  the  fasciculi  of  the  corpora  pyramidalia 
and  olivaria.  These  two  layers,  the  superior  and  inferior,  are  col- 
lected together  on  each  side,  in  the  formation  of  the  crura  cerebelli. 


SPINAL  CORD.  383 


SPINAL  CORD. 


The  dissection  of  the  spinal  cord  requires  that  the  spinal  column 
should  be  opened  throughout  its  entire  length  by  sawing  through  the 
laminae  of  the  vertebrae,  close  to  the  roots  of  the  transverse  processes, 
and  raising  the  arches  with  a  chisel,  after  the  muscles  of  the  back 
have  been  removed. 

The  Spinal  column  contains  the  spinal  cord,  or  medulla  spinalis ; 
the  roots  of  the  spinal  nerves ;  and  the  membranes  of  the  cord,  viz., 
dura  mater,  arachnoid,  pia  mater,  and  memhrana  dentata. 

The  Dura  mater  (tlieca  vertebralis)  is  continuous  with  the  dura 
mater  of  the  skull :  it  is  closely  attached  around  the  border  of  the 
occipital  foramen,  particularly  in  front,  where  it  is  connected  with 
the  posterior  common  ligament.  In  the  vertebral  canal  it  is  connected 
only  by  loose  cellular  tissue,  containing  an  oily  fluid,  somewhat 
analogous  to  the  marrow  of  long  bones.  On  either  side  and  below, 
it  forms  a  sheath,  for  each  of  the  spinal  nerves,  to  which  it  is  closely 
adherent.  Upon  its  inner  surface  it  is  smooth,  being  lined  by  the 
arachnoid ;  and  on  the  sides  may  be  seen  the  double  openings  for 
the  two  roots  of  each  of  the  spinal  nerves. 

The  Jlracknoid  is  a  continuation  of  the  serous  membrane  of  the 
brain.  It  encloses  the  cord  very  loosely,  being  connected  to  it  only 
by  long  slender  cellular  filaments,  and  by  a  longitudinal  lamella 
which  is  attached  to  the  posterior  aspect  of  the  cord.  It  passes  off 
on  either  side  with  the  spinal  nerves,  to  which  it  forms  a  sheath ; 
and  is  then  reflected  upon  the  dura  mater,  to  constitute  its  serous 
surface.  A  connexion  exists  in  several  situations  between  the  arach- 
noid of  the  cord  and  that  of  the  dura  mater. 

The  space  between  the  arachnoid  and  the  spinal  cord  is  identical 
with  that  already  described  as  existing  between  the  same  parts  in 
the  brain,  the  suh-arachnoidean  space.  It  is  occupied  in  both  by  a 
serous  fluid,  sufficient  in  quantity  to  expand  the  arachnoid,  and  fill 
completely  the  cavity  of  the  theca  vertebralis.  The  suh-arachnoi- 
dean jiuid  keeps  up  a  constant  and  gentle  pressure  upon  the  entire 
surface  of  the  brain  and  spinal  cord,  and  yields  with  the  greatest 
facility  to  the  various  movements  of  the  cord,  giving  to  those  .deli- 
cate structures  the  advantage  of  the  principles  so  usefully  applied 
by  Dr.  Arnott  in  the  hydrostatic  bed.  According  to  Majendie  this 
fluid  communicates  with  the  secretion  contained  in  the  lateral  ven- 
tricles, by  means  of  an  opening  which  exists  in  the  fibrous  layer  of 
the  inferior  boundary  of  the  fourth  ventricle. 

The  Pia  mater  is  the  immediate  investment  of  the  cord ;  and,  like 
the  other  membranes,  is  continuous  with  that  of  the  braiin.  It  is 
not,  however,  like  the  pia  mater  cerebri,  a  vascular  membrane ;  but 
is  dense  and  fibrous  in  its  structure,  and  contains  very  few  vessels. 
It  invests  the  cord  closely,  and  sends  a  duplicate  into  the  sulcus  lon- 
gitudinalis  anterior,  and  another,  extremely  delicate,  into  the  sulcus 
longitudinalis  posterior.     It  forms  a  sheath  for  each  of  the  filaments 


384  MEDULLA  SPINALIS. 

of  the  nerves,  and  for  the  nerves  themselves ;  and,  inferiorly,  at  the 
conical  termination  of  the  cord,  is  prolonged  downwards  as  a  slender 
ligament,  which  descends  through  the  centre  of  the  cauda  equina, 
and  is  attached  to  the  dura  mater  lining  the  canal  of  the  coccyx. 
This  attachment  is  a  rudiment  of  the  original  extension  of  the  spinal 
cord  into  the  canal  of  the  sacrum  and  coccyx. 

The  Memhrana  dentata  is  a  process  of  the  pia  mater  sent  off  from 
each  side  of  the  cord  throughout  its  entire  length,  and  separating 
the  anterior  from  the  posterior  roots  of  the  spinal  nerves.  Between 
each  of  the  nerves  it  forms  a  serration,  which  is  attached  to  the 
dura  mater,  and  unites  the  two  layers  of  the  arachnoid  membrane 
at  that  point.  The  processes  are  about  twenty  in  number  at  each 
side.  Their  use  is  to  maintain  the  position  of  the  spinal  cord  in  the 
midst  of  the  fluid  by  which  it  is  surrounded. 

The  Spinal  cord  of  the  adult  extends  from  the  pons  Varolii  to 
opposite  the  first  or  second  lumbar  vertebra,  where  it  terminates  in 
a  rounded  point ;  in  the  child,  at  birth,  it  reaches  to  the  middle  of 
the  third  lumbar  vertebra,  and  in  the  embryo  is  prolonged  as  far  as 
the  coccyx.  It  presents  a  difference  of  diameter  in  different  parts 
of  its  extent,  and  exhibits  three  enlargements.  The  uppermost  of 
these  is  the  medulla  oblongata ;  the  next  corresponds  with  the  origin 
of  the  nerves  destined  to  the  upper  extremities  ;  and  the  lower  en- 
largement is  situated  near  to  its  termination,  and  corresponds  with 
the  attachment  of  the  nerves  which  are  intended  for  the  supply  of 
the  lower  limb. 

In  form,  the  spinal  cord  is  a  flattened  cylinder,  and  presents  on  its 
anterior  surface  a  groove,  which  extends  into  the  cord  to  the  depth 
of  one  third  of  its  diameter.  This  is  the  sulcus  longitudinalis  ante- 
rior. If  the  sides  of  the  groove  be  gently  separated,  they  will  be 
seen  to  be  connected  at  the  bottom  by  a  layer  of  medullary  substance, 
the  anterior  commissure. 

On  the  posterior  surface  another  fissure  exists,  which  is  so  narrow 
as  to  be  hardly  perceptible  without  careful  examination.  This  is 
the  sulcus  longitudinalis  posterior.  It  extends  much  more  deeply 
into  the  cord  than  the  anterior  sulcus,  and  terminates  in  the  gray 
substance  of  the  interior.  These  two  fissures  divide  the  medulla 
spinalis  into  two  lateral  cords,  which  are  connected  to  each  other 
merely  by  the  white  commissure  which  forms  the  bottom  of  the 
anterior  longitudinal  sulcus. 

On  either  side  of  the  sulcus  longitudinalis  posterior  is  a  slight  line, 
which  bounds  on  each  side  the  posterior  median  columns.  These 
columns  are  most  apparent  at  the  upper  part  of  the  cord,  near  to  the 
fourth  ventricle,  where  they  are  separated  by  the  point  of  the  cala- 
mus scriptorius,  and  where  they  form  a  bulbous  enlargement  at  each 
side,  called  the  processus  clavatus. 

Two  other  lines  are  observed  on  the  medulla,  the  anterior  and 
posterior  lateral  sulci,  corresponding  with  the  attachment  of  the 
anterior  and  posterior  roots  of  the  spinal  nerves.  The  anterior 
lateral  sulcus  is  a  mere  trace,  marked  only  by  the  attachment  of  the 


C0LU3INS  OF  THE  SPINAL  CORD.  385 

filaments  of  the  anterior  roots.  The  'posterior  lateral  sulcus  is  more 
evident,  and  is  formed  by  a  narrow  grayish  fasciculus  derived  from 
the  gray  substance  of  the  interior. 

These  sulci  divide  the  medulla  into  four  fasciculi  or  cords,  viz. — 

Anterior  columns. 
Lateral  columns, 
Posterior  columns. 
Median  posterior  columns. 

The  Anterior  are  the  motor  columns,  and  give  origin  to  the  motor 
roots  of  the  spinal  nerves.  They  are  continued  upwards  into  the 
medulla  oblongata,  under  the  form  of  corpora  pyramidalia. 

The  Lateral  columns  are  divided  in  their  function  between  motion 
and  sensation,  and  contain  the  fasciculus  described  by  Sir  Charles 
Bell  as  the  respiratory  tract.  Some  anatomists  consider  the  ante- 
rior and  lateral  column  on  each  side  as  a  single  column,  under  the 
name  of  antero-lateral 

The  Posterior  are  the  columns  of  sensation,  and  give  origin  to  the 
sensitive  roots  of  the  spinal  nerves.  Their  superior  terminations  are 
named  corpora  restiformia. 

The  Median  posterior  columns  have  no  function  at  present  assigned 
to  them. 

If  a  transverse  section  of  the  spinal  cord  be  made,  its  internal 
structure  may  be  seen  and  examined.  It  would  then  appear  to  be 
composed  of  two  hollow  cylinders  of  white  matter,  placed  side  by 
side,  and  connected  by  a  narrow  white  commissure.  Each  cylinder 
is  filled  with  gray  substance,  which  is  connected  by  a  commissure 
of  the  same  matter.  The  form  of  the  gray  substance,  as  observed 
in  the  section,  is  that  of  two  half  moons  placed  back  to  back,  and 
joined  by  a  transverse  band.  The  horns  of  the  moons  correspond 
to  the  sulci  of  origin  of  the  anterior  and  posterior  roots  of  the  nerves. 
The  anterior  horns  do  not  quite  reach  this  surface;  but  the  posterior 
appear  upon  the  surface,  and  form  a  narrow  gray  line. 

The  white  substance  of  the  spinal  cord  is  composed  of  parallel 
fibres  which  are  collected  into  longitudinal  laminae  and  extend 
throughout  the  entire  length  of  the  cord.  These  lamina;  are  various 
in  breadth,  and  are  arranged  in  a  radiated  manner ;  one  border  being 
thick  and  corresponding  with  the  surface  of  the  cord,  while  the  other 
is  thin  and  lies  in  contact  with  the  gray  substance  of  the  interior. 
According  to  Rolando  the  white  substance  constitutes  a  simple 
nervous  membrane  which  is  folded  into  longitudinal  plaits,  having 
the  radiated  disposition  above  described.  The  anterior  commissure 
according  to  his  description  is  merely  the  continuation  of  this  ner- 
vous membrane  from  one  lateral  cord  across  the  middle  line  to  the 
other.  Moreover,  Rolando  considers  that  a  thin  lamina  of  pia  mater 
is  received  between  each  of  the  folds  from  the  exterior,  while  a  layer 
of  the  gray  substance  is  prolonged  between  them  from  within. 
Cruveilhier  is  of  opinion  that  each  lamella  is  completely  independent 
of  its  neighbours,  and  he  believes  this  statement  to  be  confirmed  by 

49 


386  OLFACTORY  NERVE. 

pathology,  which  shows  that  a  single  lamella  may  be  injured  or 
atrophied,  and  at  the  same  time  be  surrounded  by  others  perfectly 
sound. 

CRANIAL  NERVES. 

There  are  nine  pairs  of  cranial  nerves.     Taken  in  their  order 
from  before,  backv^^ards,  they  are — 

1st.  Olfactory. 

2d.   Optic. 

3d.    Motores  oculorum. 

4th.  Pathetici  (trochleares). 

5th.  Trifacial  (trigemini). 

6th.  Abducentes. 

^,1     (  Facial  (portio  dura), 

(  Auditory  (portio  mollis), 

C  Glosso-pharyngeal, 
8th.  <  Pneumogastric  (vagus,  par  vagum). 

(  Spinal  accessory. 
9th.  Hypoglossal  (lingual). 

Functionally  or  physiologically  they  are  divided  into  four  groups, 
and  in  this  order  we  shall  examine  them. 

JVerves  of 

(  1st.  Olfactory, 

1.  Special  sense     .        -      <  2d.    Optic, 

(  7th.  Auditory. 

(  3d.   Motores  oculorum, 

2.  Motion      .         .         .      <  6th.  Abducentes, 

(  9th.  Hypoglossal. 

C  4th.  Patheticus, 

3.  Respiration  {Bell)      .      <  7th.  Facial, 

^8th.  Glosso-pharyngeal. 
Pneumogastric, 
Spinal  accessory. 

4.  Spinal      .         .         .         5th.  Trifacial. 


NERVES  OF  SPECIAL  SENSE. 

1st  pair,  Olfactory. — This  nerve  rests  against  the  under  surface 
of  the  anterior  lobe  of  the  brain,  being  lodged  in  the  narrow  interval 
between  two  convolutions,  and  retained  in  its  place  by  the  arachnoid 
membrane. 

It  arises  by  three  roots,  I.  Internal,  from  the  substantia  perforata. 
2.  Middle,  from  a  papilla  of  gray  matter  embedded  in  the  anterior 


OPTIC  NERVE AUDITORY  NERVE.  387 

lobe.  3.  External,  from  a  long  fasciculus  which  is  traced  for  a 
considerable  distance  along  the  fissure  of  Sylvius,  into  the  middle 
lobe.  The  union  of  these  roots  forms  a  grayish  white  nerve,  pris- 
moid  in  form  and  soft  in  structure,  which  expands  into  a  hulb  {bulbus 
olfactorms),  and  rests  upon  the  cribriform  plate.  Its  branches  are 
transmitted  through  the  numerous  foramina  in  the  cribriform  plate, 
to  be  distributed  to  the  mucous  membrane  of  the  nr»se.  The  inner- 
most are  reddish  in  colour  and  soft,  and  spread  out  upon  the  septum 
narium;  the  external  branches  are  whiter  and  more  firm,  they  pass 
through  bony  canals  in  the  outer  wall  of  the  nose,  and  communicate 
freely  with  each  other  previously  to  their  distribution  in  the  mucous 
membrane  of  the  superior  and  middle  turbinated  bones. 

2d  pair.  Optic. — The  optic  nerve  arises  by  two  roots;  one  from 
the  corpus  geniculatum  externum,  the  other  from  the  anterior  pair 
(nates)  of  the  corpora  quadrigemina  or  optic  lobes.  It  winds  around 
the  crus  cerebri  as  a  flattened  band,  and  unites  with  its  fellow  of  the 
opposite  side,  to  form  the  commissure.  The  two  nerves  then  diverge 
from  each  other,  to  enter  the  orbit  through  the  optic  foramen,  pierce 
the  sclerotic  and  choroid  coat  of  the  eyeball,  and  expand  in  the 
retina.  The  optic  commissure  rests  upon  the  processus  olivaris  of 
the  sphenoid  bone,  and  its  posterior  border  is  closely  connected  with 
the  tuber  cinereum,  from  which  it  receives  fibres ;  in  its  interior  the 
innermost  fibres  of  the  two  nerves  cross  each  other,  while  the  exter- 
nal proceed  directly  onwards  in  their  course.  On  entering  the  orbit 
the  nerve  obtains  a  firm  sheath  from  the  dura  mater,  which  is  con- 
tinuous with  the  sclerotic  coat  of  the  eyeball.  This  sheath  is  formed 
by  the  splitting  of  the  dura  mater  at  the  foramen  opticum  into  two 
layers,  the  one  surrounding  the  optic  nerve,  while  the  other  is  con- 
tinuous with  the  periosteum  of  the  orbit.  Near  to  the  globe  of  the 
eyeball  the  optic  nerve  is  pierced  by  the  arteria  centralis  retinae, 
which  runs  forwards  in  the  centre  of  the  nerve,  and  reaching  the 
retina  distributes  branches  upon  its  internal  surface,  forming  its 
vascular  layer. 

7th  pair,  Auditory  (poriio  mollis). — This  nerve  arises  from  the 
anterior  wall  or  floor  of  the  fourth  ventricle,  by  means  of  the  white 
fibres,  linecE  transversce,  of  the  calamus  scriptorius.  It  winds  around 
the  corpus  restiforme,  from  which  it  receives  fibres,  and  emerges 
upon  the  posterior  border  of  the  crus  cerebelli :  it  then  enters  the 
meatus  auditorius  internus,  together  with  the  facial  nerve,  which 
lies  in  a  groove  on  its  superior  and  anterior  surface,  and  at  the 
bottom  of  the  meatus  divides  into  two  branches,  cochlear  and  vestibu- 
lar, which  are  distributed  to  the  internal  ear.  It  is  soft  and  pulpy 
in  texture,  and  whilst  situated  in  the  meatus  auditorius  sends  several 
filaments  to  the  facial  nerve. 

NERVES  OF  MOTION. 

We  have  already  seen  that  the  corpora  pyramidalia  are  the  con- 


388 


MOTORES  OCULORU3I ABDUCENTES. 


tinuations  up-\vards  of  the  anterior  columns  of  the  spinal  cord,  or 
motor  tract,  and  that  these  fascicuh  are  prolonged  onwards  through 
the  pons  Varolii  and  crura  cerebri  into  the  ganglia  of  the  hemi- 
spheres. ■  Now,  the  three  motor  nerves  arise  from  the  cerebral  por- 
tion of  the  motor  tract  at  different  points  of  its  course. 

3d  pair,  Motores  Oculorum. — The  motor  oculi  nerve  arises  from 
the  inner  side  of  the  crus  cerebri,  near  to  the  pons  Varoli,  and  passes 

forward  between  the  posterior 
Fig.  128.*  cerebral  and  superior  cerebellar 

artery.  It  pierces  the  dura 
mater  immediately  in  front  of 
the  posterior  clinoid  process ; 
descends  obliquely  along  the  ex- 
ternal wall  of  the  cavernous 
sinus;  and  divides  into  two 
branches  which  enter  the  orbit 
between  the  two  heads  of  the 
external  rectus  muscle.  The 
siiferior  branch  ascends,  and 
supplies  the  superior  rectus  and 
levator  palpebrEe.  The  inferior 
sends  a  branch  beneath  the  optic 
nerve  to  the  internal  rectus, 
another  to  the  inferior  rectus, 
and  a  long  branch  to  the  in- 
ferior oblique  muscle.  From 
the  latter  a  short  thick  branch 
is  given  off  to  the  ciliary  gan- 
glion, forming  its  inferior  root. 
The  fibres  of  origin  of  this 
nerve  may  be  traced  into  the  gray  substance  of  the  crus  cerebri,f 
into  the  motor  tractj  and  as  far  as  the  superior  fibres  of  the  crus 
cerebri.§      In   the  cavernous    sinus  it  receives  one  or  two  fila- 


*  The  anatomy  of  the  side  of  the  neck,  showing  the  nerves  of  the  tongue.  1 .  A  frag- 
ment of  the  temporal  bone  containing  the  meatus  auditorius  externus,  mastoid,  and 
styloid  process.  2,  Tiie  stylo-hyoid  muscle.  3.  The  stylo-glossus.  4.  The  stylo- 
pharyngcus.  5.  The  tanguc.  6.  The  hyo-glossus  muscle ;  its  two  portions.  7.  The 
gcnio-hyo-glossus  muscle.  8.  The  genio-hyoidcus;  they  both  arise  from  the  inner  sur- 
face of  the  symf)hysis  of  the  lower  jaw.  f).  The  sterno-hyoid  muscle.  10.  The  sterno- 
thyroid.  11.  The  thyro-hyoid,  u|)ori  which  the  hyoid  branch  of  the  lingual  nerve  is 
seen  ramifying.  12.  The  omo-iiyoid  crossing  the  common  carotid  artery  (13),  and  in- 
ternal jugular  vein  (14).  1.5.  Tiie  external  carotid  giving  off  its  branches.  16.  The 
internal  carotid.  17.  The  gustatory  nerve  giving  off  a  brancli  to  the  submaxillary 
ganglion  (18),  and  communicating  a  little  further  on  witii  tlic  hypoglossal  nerve.  19. 
The  submaxillary,  or  Wharton's  duct,  passing  forwards  to  the  sublingual  gland.  20. 
The  glosso-pharyngeal  nerve.  21.  The  hypoglossal  nerve  curving  around  the  occipital 
artery.  22.  The  desccndens  noni  nerve,  forming  a  loop  with  (23)  the  communicans 
noni,  which  is  seen  to  be  arising  by  filaments  from  tlic  u])per  cervical  nerves.  24.  The 
pneumogastric  nerve,  emerging  from  between  the  internal  jugular  vein  and  common 
carotid  artery,  and  entering  the  chest.  2.5.  The  facial  nerve,  emerging  from  the  stylo- 
mastoid foramen,  and  cro.ssing  the  external  carotid  artery. 

t  Mayo.  t  Solly.  §  Grainger. 


HYPOGLOSSAL  NERVE.  389 

ments  from  the  cavernous  plexus,  and  one  from  the  ophthalmic 
nerve. 

6th  pah%  Abducentes. — The  abclucens  nei've  arises  from  the  upper 
part  of  the  corpus  jjyramidale,  close  to  the  pons  Varolii,  several  of 
its  filaments  of  origin  passing  between  the  fascicuH  of  the  pons.  It 
pierces  the  dura  mater  upon  the  basilar  process  of  the  sphenoid 
bone,  and  ascends  to  the  cavernous  sinus.  It  then  runs  forward  along 
the  inner  wall  of  the  sinus,  below  the  other  nerves ;  and,  resting 
against  the  internal  carotid  artery,  passes  between  the  two  heads  of 
the  external  rectus,  and  is  distributed  to  that  muscle.  As  it  enters 
the  orbit  it  lies  upon  the  ophthalmic  vein,  from  which  it  is  separated 
by  a  lamina  of  dura  mater.  In  the  cavernous  sinus  it  is  joined  by 
two  filaments  from  the  carotid  plexus,  and  by  one  from  the  ophthal- 
mic nerve.  Mr.  Mayo  has  traced  the  origin  of  this  nerve  between 
the  fasciculi  of  the  corpora  pyramidalia  to  the  posterior  part  of  the 
medulla  oblongata ;  and  Mr.  Grainger  has  pointed  out  its  connexion 
with  the  gray  substance  of  the  spinal  cord. 

9th  pair.  Hypoglossal  (lingual). — The  ninth  nerve,  the  true  mo- 
tor nerve  of  the  tongue,  arises  by  eight  or  ten  filaments  from  the 
side  of  the  corpus  pyramidale  of  the  medulla  oblongata.  These 
filaments  are  disposed  in  two  fasciculi  which  unite  into  a  single 
nerve  at  the  jMNteMer  condyloid  foramen.  The  lingual  nerve  then  ^ 
passes  forward  between  the  internal  carotid  artery  and  internal 
jugular  vein,  and  descends  along  the  anterior  and  inner  side  of  the 
vein  to  a  point  parallel  with  the  angle  of  the  lower  jaw.  It  next 
curves  inwards  around  the  occipital  artery,  with  which  it  forms  a 
loop,  and  crosses  the  lower  part  of  the  hyo-glossus  muscle  to  the 
genio-hyo-glossus,  in  which  it  terminates  by  sending  filaments  on- 
wards with  the  anterior  fibres  of  this  muscle  as  far  as  the  tip  of  the 
tongue.  It  is  distributed  to  the  muscles  of  the  tongue,  and  princi- 
pally to  the  genio-hyo-glossus.  While  resting  on  the  hyo-glossus 
muscle  it  has  a  flattened  appearance,  and  communicates  beneath  the 
mylo-hyoideus  of  the  gustatory  nerve. 

The  Branches  of  the  hypoglossal  nerve  are : — 

Communicating  branches  with  the  Pneumogastric, 

Spinal  accessory, 
First  and  second  cervical 

nerves, 
Sympathetic. 

Descendens  noni, 

Hyoidean  branch. 

Communicating  filaments  with  the  gustatory  nerve. 

The  Communications  with  the  pneumogastric  and  spinal  acces- 
sory take  place  through  the  medium  of  a  plexiform  interlacement  of 
branches  at  the  base  of  the  skull,  behind  the  internal  jugular  vein. 
The  communications  with  the  sympathetic  nerve  are  derived  from 
the  superior  cervical  ganglion. 


390  RESPIKATORY  NERVES. 

The  Descendens  noni  is  a  long  slender  twig,  which  quits  the  hypo- 
glossal just  as  that  nerve  is  about  to  form  its  arch  around  the  occipi- 
tal-artery, and  descends  upon  the  sheath  of  the  carotid  vessels.  Just 
below  the  middle  of  the  neck  it  forms  a  loop  with  a  long  branch 
(communicans  noni)  from  the  second  and  third  cervical  nerves. 
From  the  convexity  of  this  loop  branches  are  sent  to  the  depressor 
muscles  of  the  larynx.  If  the  descendens  noni  be  traced  to  its  con- 
nexion with  the  hypoglossal  nerve,  and  examined  with  care,  it  will 
be  found  to  be  formed  by  two  filaments,  one  from  the  lingual,  the 
other,  of  larger  size,  from  the  first  and  second  cervical  nerves. 

The  Hyoidean  branch  is  a  small  twig  distributed  to  the  insertions 
of  the  depressor  muscles  of  the  larynx,  particularly  to  the  thyro- 
hyoid. 

The  Communicating  filaments  with  the  gustatory  nerve  are  two 
or  three  small  branches  which  ascend  upon  the  anterior  part  of  the 
hyo-glossus  muscle,  and  join  corresponding  branches  sent  down- 
wards by  the  gustatory. 

RESPIRATORY  NERVES. 

*  Under  this  head  are  grouped,  by  Sir  Charles  Bell,  certain  nerves 
^^  *  '•  which  are  associated  in  the  movements  of  respiration.  They  all 
arise  in  the  course  of  a  distinct  tract,  situated  between  the  corpus 
olivare  and  corpus  restiforme  on  each  side  of  the  medulla  oblongata, 
and  which  may  be  traced  upwards  to  the  corpora  quadrigemina ; 
hence  this  portion  of  the  brain  has  been  named  the  respiratory 
tract. 

4th  pair,  Pathetici  (trochlearis). — The  fourth  is  the  smallest 
cerebral  nerve ;  it  arises  from  the  valve  of  Vieussens  and  testis,  and 
winds  around  the  crus  cerebri  to  the  extremity  of  the  petrous  por- 
tion of  the  temporal  bone,  where  it  pierces  the  dura  mater  near  to 
the  oval  opening  for  the  fifth  nerve,  and  passes  along  the  outer  wall 
of  the  cavernous  sinus  to  the  sphenoidal  fissure.  In  its  course 
through  the  sinus  it  is  situated  at  first  below  the  motor  oculi,  but 
afterwards  ascends  and  becomes  the  highest  of  the  nerves  which 
enter  the  orbit  through  the  sphenoidal  fissure. 

After  reaching  the  orbit  it  crosses  the  levator  palpebraj  muscle 
near  to  its  origin,  and  is  distributed  upon  the  orbital  surface  of  the 
superior  oblique  or  trochlearis  muscle ;  hence  its  synonyme  ti'ocli- 
learis. 

Branches. — While  in  the  cavernous  sinus  the  fourth  nerve  gives 
off  a  recurrent  branch ;  some  filaments  of  communication  to  the 
ophthalmic  nerve  ;  and  a  branch  to  assist  in  forming  the  lachrymal 
nerve.  The  recurrent  branch  passes  backwards  between  the  layers 
of  the  tentorium  and  divides  into  two  or  three  filaments,  which  are 
distributed  to  the  lining  membrane  of  the  lateral  sinus.  In  a  prepa- 
ration before  me  this  i)ranch  is  very  distinct;  but  I  have  not  always 
succeeded  in  finding  it. 


FACIAL  NERVE.  3&1 

7th  pair,  Facial  {portio  dura.)  The  Facial  nerve  arises  from 
the  respiratory  tract,  at  the  upper  part  of  the  medulla  oblongata 
close  to  the  lower  border  of  the  pons  Vai'olii,  from  which  point  its 
fibres  may  be  traced  deeply  into  the  corpus  restiforme.  It  enters 
the  meatus  auditorius  internus  in  front  of  and  superiorly  to  the 
auditory  nerve  (portio  molUs),  and  at  the  bottom  of  the  meatus 
passes  into  the  canal  which  is  expressly  intended  for  it,  the  aque- 
ductus  Fallopii.  In  this  canal  it  dh'ects  its  course  at  first  forwards 
towards  the  hiatus  Fallopii,  where  it  forms  a  gangliform  swelUng, 
and  receives  the  petrosal  branch  of  the  Vidian  nerve.  It  then  curves 
backwards  towards  the  tympanum,  and  descends  along  its  inner 
wall  to  the  stylo-mastoid  foramen.  Emerging  at  the  stylo-mastoid 
foramen  it  passes  forwards  within  the  parotid  gland,  and  crosses  the 
external  jugular  vein  and  external  carotid  artery  to  the  ramus  of  the 
jaw.  While  situated  within  the  gland  it  is  joined  by  a  branch  from 
the  auricular  nerve,  and  divides  into  two  trunks — the  temporo-facial 
and  cervico-facial — which  communicate  with  each  other  and  give 
off"  the  numerous  branches  which  constitute  the  pes  anserinus,  and 
are  distributed  over  the  whole  of  the  side  of  the  face,  supplying  the 
muscles. 

The  Branches  of  the  facial  nerve  are — 

Within   the    aqueductus    (  Tympanic, 
Fallopii,  (  (Chorda  tympani).* 

r  Communicating, 
After   emerging    at   the  >  Posterior  auricular, 
stylo-mastoid  foramen,  j  Digastric, 
(^  Stylo-hyoid. 

/-,    ,7    ^  (  Temporo-facial, 

Un  the  face,  ^  ^      v      r    •  i  j. 

^  i  Cervico-iacial.j 

The  Tympanic  branches  are  two  small  filaments,  which  are  dis- 
tributed to  the  stapedius  and  tensor  tympani  muscle. 

The  Chorda  tympani  quits  the  facial  just  before  that  nerve  emerges 
from  the  stylo-mastoid  foramen.  Entering  the  tympanum  at  its 
posterior  and  superior  angle,  it  crosses  its  cavity  between  the  handle 
of  the  malleus  and  long  process  of  the  incus,  to  its  anterior  inferior 
angle.  It  then  escapes  through  a  distinct  opening  in  the  fissura 
Glaseri,  and  joins  the  gustatory  nerve  at  an  acute  angle  between 

*  The  chorda  tympani  is  not  considered  as  a  branch  of  the  facial ;  but  being  in  close 
connexion  with  it,  and  being  given  off  from  it  like  a  branch  I  have  inserted  it  here 
lest  it  should  be  overlooked. 

+  A  third  series  of  branches  is  usually  described,  whicli  arc  included  by  Wilson  in 
his  temporo-facial  branches.  They  are  called  buccal  from  supplying  the  neighbourhood 
of  the  buccinator  muscle. — G. 


392 


FACIAL  NERVE. 


the  t^vo  pterygoid  muscles.  Enclosed  in  the  sheath  of  the  gustatory 
nerve,  it  descends  to  the  submaxillary  gland,  where  it  unites  with 
the  submaxillary  ganglion. 

The  Communicating  branches  are  filaments  which  it  receives 
from  the  glosso-pharyngeal  and  pneumogastric  nerves. 

The  Posterior  auricular  nerve  ascends  behind  the  ear,  and  crosses 
the  mastoid  process  to  the  occipito-frontalis  muscle ;  it  gives 
branches  also  to  the  attollens  and  retrahens  muscles  of  the  pinna. 

The   Digastric  branch 
Fig.  129.*  supplies  the  posterior  belly 

of  the  digastricus  muscle. 
The  Stijlo-hyoid  branch 
is  distributed  to  the  stylo- 
hyoid muscle. 

The  Temforo-facial 
gives  off  a  number  of 
branches  which  are  dis- 
tributed over  the  temple 
and  upper  half  of  the  face, 
supplying  the  muscles  of 
this  region,  and  commu- 
nicating with  the  branches 
of  the  auricular,  the  tem- 
poro-malar,  and  the  su- 
pra-orbital nerve.  The 
inferior  branches,  which 
accompany  Stenon's  duct, 
form  a  plexus  with  the 
terminal  branches  of  the 
infra-orbital  nerve. 

The  Cervico-facial  di- 
vides into  a  number  of  branches  that  are  distributed  to  the  muscles 
on  the  lower  half  of  the  face,  and  upper  part  of  the  neck.  The 
cervical  branches  form  a  plexus  with  the  superficialis  colli  nerve 
over  the  submaxillary  gland. 

*  The  distribution  of  the  facial  nerve  and  the  branches  of  the  cervical  plexus.  1. 
The  facial  nerve,  escaping-  from  tlie  stylo-mastoid  foramen,  and  crossing-  the  ramus  of 
the  lower  jaw ;  the  parotid  gland  has  been  removed  in  order  to  see  the  nerve  more  dis- 
tinctly.  2.  The  posterior  auricular  bi-anch ;  tlie  digastric  and  stylo-mastoid  filaments 
are  seen  near  the  origin  of  this  branch.  .3.  Temporal  branches,  comrnunicating  -with 
(4)  the  branches  of  the  frontal  nerve.  5.  Facial  brandies,  communicating  -with  (6)  the 
infra-orbital  nerve.  7.  Facial  branches,  communicating  with  (8)  tlie  mental  nerve.  9. 
Cervico-facial  branches  communicating  with  (10)  the  superficialis  colli  nerve,  and 
-forming  a  plexus  (11)  over  the  submaxillary  gland.  The  distribution  of  the  branches 
of  the  facial  in  a  radiated  direction  over  the  side  of  the  face  constitutes  tlic  pes  anse- 
rinus,  12.  The  auricularis  magnus  nerve,  one  of  tlie  ascending  brandies  of  the  cer- 
vical plexus.  13.  The  occipitalis  minor,  ascending  along  the  posterior  border  of  the 
sterno-mastoid  muscle.  14.  The  superficial  and  deep  descending  branches  of  the  cer- 
vical  plexus.  15.  The  spinal  accessory  nerve,  giving  off  a  braneli  to  the  external  sur- 
face of  the  trapezius  muscle.  16.  The  occipitalis  major  nerve,  tiio  posterior  branch  of 
the  second  cervical  nerve. 


GLOSSO-PHARYNGEAL  NERVE.  393 

The  facial  nerve  has  been  named  sympailieticus  minor,  on  account 
of  the  number  of  communications  which  it  maintains  with  other 
nerves.     These  will  be  best  seen  in  a  tabular  arrangement : 

r    ^t        J  7         ui.  Auditory  nerve, 

In  the  petrous  hone  it     petrosal  branch  of  Vidian, 
communicates  with    ^  ^^.^  ganglion. 

At   its   exit    from    the  (  ^,  ,  , 

styh-mastoid    fora-     glosso-pharyngeal, 

^         •,,  -^         i  rneumoo;astric. 

men,  with  (  ° 

,     ,,  ,- 1     T     J  r  Anterior  auricular, 

In  the  parotid  gland,  \  ^uricularis  magnus, 


ivith 


Occipitalis  minor. 


Supra-orbital, 
Infra-orbital, 
On  the  face  and  neck,  J  Temporo-malar, 
with  \  Buccal, 

Mental, 
Superficialis  colli. 

8th  pair. — This  pair  consists  of  three  nerves,  the  glosso-pharyn- 
geal,  pneumogastric,  and  spinal  accessory. 

The  Glosso-pharyngeal  Nerve  arises  by  several  filaments  from 
the  respiratory  tract,  between  the  corpus  olivare  and  restiforme, 
and  escapes  from  the  skull  at  the  innermost  extremity  of  the  jugular 
foramen  through  a  distinct  opening  in  the  dura  mater,  lying  ante- 
riorly to  the  sheath  of  the  pneumogastric  and  spinal  accessory 
nerves,  and  internally  to  the  jugular  vein.  It  then  passes  for- 
wards between  the  jugular  vein  and  internal  carotid  artery  to 
the  stylo-pharyngeus  muscle,  and  descends  along  its  inferior  border 
to  the  hyo-glossus,  beneath  which  it  passes  to  be  distributed  to  the 
mucous  membrane  of  the  base  of  the  tongue  and  fauces,  to  the 
mucous  glands  of  the  mouth,  and  to  the  tonsils.  While  situated 
in  the  jugular  fossa,  the  nerve  presents  two  gangliform  swellings, 
one  superior  (ganglion  jugulare  of  Miiller)  of  small  size,  and  in- 
volving only  the  posterior  fibres  of  the  nerve,  the  other  inferior, 
nearly  half  an  inch  below  the  preceding,  of  larger  size  and  occupy- 
ing the  whole  diameter  of  the  nerve,  the  ganglion  of  Andersch* 
(ganglion  petrosum). 

The  fibres  of  origin  of  this  nerve  may  be  traced  through  the  fas- 
ciculi of  the  corpus  restiforme  to  the  gray  substance  in  the  floor  of 
the  fourth  ventricle. 

*  Charles  Samuel  Andersch.  "  Tractatus  Anatomico-Physiologicus  de  Nervis  Cor- 
poris Humani  Aliquibus,  1797." 

50 


394  PNEUMOOASTRIC  NERVE. 

The  Branches  of  the  glosso-pharyngeal  nerve  are — 

Communicating  branches  with  the  Facial, 

Pneumogastric, 
Spinal  accessory, 
Sympathetic. 

Tympanic, 

Muscular, 

Pharyngeal, 

Lingual, 

Tonsillitic. 

The  Branches  of  communication  proceed  from  the  ganglion  and 
from  the  upper  part  of  the  trunk  of  the  nerve,  and  are  common  to 
the  facial,  eighth  pair,  and  sympathetic ;  they  form  a  complicated 
plexus  at  the  base  of  the  skull. 

The  Tijmpanic  branch  (Jacobson's  nerve)  enters  a  small  bony 
canal  in  the  petrous  portion  of  the  temporal  bone,  and  divides  into 
six  branches,  which  are  distributed  upon  the  inner  wall  of  the  tym- 
panum, and  establish  important  communications  with  the  sympathetic 
and  fifth  pair  of  nerves.  The  branches  of  distribution  supply  the 
fenestra  rotunda,  fenestra  ovalis,  and  Eustachian  tube :  those  of 
communication  join  the  carotid  plexus,  the  petrosal  branch  of  the 
Vidian  nerve,  and  the  otic  ganglion. 

The  Muscular  branch  divides  into  filaments,  which  are  distributed 
to  the  stylo-pharyngeus  and  to  the  posterior  belly  of  the  digastricus 
and  stylo-hyoideus  muscle. 

The  Pharyngeal  branches  are  two  or  three  filaments  which  are 
distributed  to  the  pharynx  and  unite  with  the  pharyngeal  branches 
of  the  pneumogastric  and  of  the  sympathetic  nerve  to  form  the 
pharyngeal  plexus. 

The  Lingual  branches  enter  the  substance  of  the  tongue  beneath 
the  hyo-glossus  and  stylo-glossus  muscle,  and  are  distributed  to  the 
mucous  membrane  of  the  side  and  base  of  the  tongue,  and  to  the 
fauces. 

The  Tonsillitic  branches  proceed  from  the  glosso-pharyngeal  nerve 
near  to  its  termination  ;  they  form  a  plexus  (circulus  tonsillaris) 
around  the  base  of  the  tonsil,  from  which  numerous  filaments  are 
giv^en  oflf  to  the  mucous  membrane  of  the  fauces  and  soft  palate, 
communicating  with  the  posterior  palatine  branches  of  Meckel's 
ganglion. 

The  Pneumogastric  Nerve  (vagus)  arises  by  numerous  filaments 
from  the  respiratory  tract  immediately  below  the  glosso-pharyngeal, 
and  passes  out  of  the  skull  through  the  inner  extremity  of  the 
jugular  foramen  in  a  distinct  canal  of  the  dura  mater.  While 
situated  in  this  canal  it  presents  a  small  rounded  ganglion ;  and 
having  escaped  from  the  skull,  a  gangliform  swelling,  nearly  an  inch 
in  length,  and  surrounded  by  an  irregular  plexus  of  white  nerves, 


PNEUMOOASTRIC  NERVE BRANCHES.  395 

which  communicate  with  each  other,  with  the  other  divisions  of  the 
eighth  pair,  and  with  the  trunk  of  the  pneumogastric  below  the 
gangUon.  This  second,  or  plexiform  ganglion  (ganglion  of  the  su- 
perior laryngeal  branch,  of  Sir  Astley  Cooper),  is  situated,  at  first, 
behind  the  internal  carotid  artery,  and  then  between  that  vessel  and 
the  internal  jugular  vein.  The  pneumogastric  nerve  then  descends 
the  neck  within  the  sheath  of  the  carotid  vessels,  lying  behind  and 
between  the  artery  and  vein,  to  the  root  of  the  neck.  Here  the 
course  of  the  nerve  at  opposite  sides  becomes  different. 

The  Right  passes  between  the  subclavian  artery  and  vein  to  the 
posterior  mediastinum,  then  behind  the  root  of  the  lung  to  the  oeso- 
phagus, which  it  accompanies  to  the  stomach,  lying  on  its  posterior 
aspect. 

The  Left  enters  the  chest  parallel  with  the  left  subclavian  artery, 
crosses  the  arch  of  the  aorta,  and  descends  behind  the  root  of  the 
lung,  and  along  the  anterior  surface  of  the  oesophagus,  to  the 
stomach. 

The  fibres  of  origin  of  the  pneumogastric  nerve,  like  those  of  the 
glosso-pharyngeal,  may  be  traced  through  the  fasciculi  of  the 
corpus  restiforme  into  the  gray  substance  of  the  floor  of  the  fourth 
ventricle. 

The  Branches  of  the  pneumogastric  nerve  are  the  following : — 

Communicating  branches  with  the  Facial, 

Glosso-pharyngeal, 
Spinal  accessory, 
H}TO-glossal, 
Sympathetic. 

Pharyngeal, 

Superior  laryngeal, 

Cardiac, 

Inferior  or  recurrent  laryngeal. 

Pulmonary  anterior. 

Pulmonary  posterior, 

CEsophageal, 

Gastric. 

The  Branches  of  communication  form  part  of  the  complicated 
plexus  at  the  base  of  the  skull.  The  branches  to  the  ganglion  of 
Andersch,  and  that  to  the  facial  nerve,  are  given  oft"  by  the  superior 
ganglion  in  the  jugular  fossa ;  the  latter  passes  through  a  minute 
canal  in  the  petrous  bone,  to  the  lower  part  of  the  aqueductus 
Fallopii. 

The  Pharyngeal  nerve  arises  from  the  pneumogastric,  immediately 
above  the  plexifarm  ganglion,  and  descends  behind  the  internal 
carotid  artery  to  the  upper  border  of  the  middle  constrictor,  upon 
which  it  forms  the  pharyngeal  plexus  assisted  by  branches  from  the 
glosso-pharyngeal,  superior  laryngeal,  and  sympathetic.  The  pharyn- 


396 


EIGHTH  PAIR  OF  NERVES. 


Fig.  130.*  geal  plexus  is  distributed  to  the  muscles 

and  mucous  membrane  of  the  pharynx. 

The  Superior  laryngeal  nerve  arises 
from  the  inferior  ganglion  of  the  pneumo- 
gastric,  of  which  it  appears  to  be  almost  a 
continuation ;  hence  the  ganglion  has  been 
named  by  Sir  Astley  Cooper,  the  ^^ ganglion 
of  the  superior  laryngeal  branch."  The 
nerve  descends  behind  the  internal  carotid 
artery  to  the  opening  in  the  thyro-hyoidean 
membrane,  through  which  it  passes  with 
the  superior  laryngeal  artery,  and  is  dis- 
tributed to  the  mucous  membrane  of  the 
larynx,  communicating  on  the  arytenoid 
muscle,  and  behind  the  cricoid  cartilage, 
with  the  recurrent  laryngeal  nerve.  Be- 
hind the  internal  carotid  it  gives  off  the 
external  laryngeal  branch,  which  sends  a 
branch  to  the  pharyngeal  plexus,  and  then 
descends  to  supply  the  inferior  constrictor 
and  crico-thyroid  muscles  and  thyroid 
gland,  and  communicates  by  two  or  three 
branches  with  the  recurrent  laryngeal  and 
sympathetic  nerve. 

Mr.  John  Hilton,  demonstrator  of  ana- 
tomy in  Guy's  Hospital,  who  has  made 
some  able  dissections  of  the  nerves  of  the 
larynx,  of  which  we  refer  the  student  to  a 
masterly  description  in  the  2d  vol.  of  the 
Guy's  Hospital  Reports,  concludes  that  the 
superior  laryngeal  nerve  is  the  nerve  of 
sensation  to  the  larynx,  being  distributed 
solely  (with  the  exception  of  its  external 
laryngeal  branch)  to  the  mucous  mem- 
brane, cellular  tissue,  and  glands.  If  this 
fact  be  taken  in  connexion  with  the  obser- 
vations of  Sir  Astley  Cooper,  and  the  dis- 
sections of  the  origin  of  the  nerve  by  Mr.  Edward  Cock,  we  shall 
perceive  that,  both  in  the  ganglionic  origin  of  the  nerve  and  in  its 

*  Orij»'in  and  distribution  of  the  cijrhth  pair  of  nerves,  1.  3,  4.  The  medulla  oblon- 
gata. 1.  Is  the  corpus  pyraniidalc  of  one  side.  3.  The  corpus  olivare.  4.  The  corpus 
restiforme.  2.  The  pons  Varolii.  5.  The  facial  nci'vo.  6.  The  orij^in  of  the  glosso- 
pharyngeal  nerve.  7.  The  ganglion  of  Andcrsch.  8.  Tlie  trunk  of  tiie  nerve.  9.  The 
spinal  accessory  nerve.  10.  The  ganglion  of  tlic  pncumogastric  nerve.  11.  Its  plexi- 
form  ganglion.  12.  Its  trunk.  13.  Its  pliaryngeal  branch  forming  the  pharyngeal 
plexus  (14),  assisted  by  a  branch  from  the  glosso-pliaryngeal  (H),  and  one  from  the 
superior  laryngeal  nerve  (1.5).  IG.  Cardiac  ])ranches.  17.  Recurrent  laryngeal 
branch.  IS.  Anterior  pulmonary  branches.  19.  Posterior  pulmonary  branches.  20. 
Qilsophageal  plexus.  21.  Gastric  branches.  29.  Origin  of  the  spinal  accessory  nerve. 
23.  Its  branches  distributed  to  the  stcrno-mastoid  muscle.  24,  Its  branches  to  the 
trapezius  muscle. 


SPINAL  ACCESSORY  NERVE.  397 

distribution,  we  have  striking  evidence  of  its  sensitive  function.  The 
recurrent,  or  inferior  laryngeal  nerve,  is  the  proper  motor  nerve, 
and  is  distributed  to  the  muscles  of  the  larynx. 

The  Cardiac  branches,  two  or  three  in  number,  arise  from  the 
pneumogastric  in  the  lower  part  of  the  neck,  and  cross  the  lower 
part  of  the  common  carotid,  to  communicate  with  the  cardiac 
branches  of  the  sympathetic,  and  with  the  great  cardiac  plexus. 

The  Recurrent  laryngeal,  or  inferior  laryngeal  nerve,  curves 
around  the  subclavian  artery  on  the  right,  and  the  arch  of  the  aorta 
on  the  left  side.  It  ascends  in  the  groove  between  the  trachea 
and  oesophagus,  and  piercing  the  lower  fibres  of  the  inferior  con- 
strictor muscle  enters  the  larynx  close  to  the  articulation  of  the 
inferior  cornu  of  the  thyroid  with  the  cricoid  cartilage.  It  is  distri- 
buted to  all  the  muscles  of  the  larynx,  with  the  exception  of  the 
crico-thyroid,  and  communicates  with  the  superior  laryngeal  nerve. 
As  it  curves  around  the  subclavian  artery  and  aorta  it  gives 
branches  to  the  heart  and  root  of  the  lungs ;  and  as  it  ascends  the 
neck  it  distributes  filaments  to  the  oesophagus  and  trachea,  and  com- 
municates with  the  external  laryngeal  nerve  and  sympathetic. 

The  Anterior  fulmonary  branches  are  distributed  upon  the  ante- 
rior aspect  of  the  root  of  the  lungs,  forming,  with  branches  from 
the  great  cardiac  plexus,  the  anterior  'pulmonary  flexus. 

The  Posterior  pulmonary  branches,  more  numerous  than  the  ante- 
rior, are  distributed  upon  the  posterior  aspect  of  the  root  of  the 
lungs,  and  are  joined  by  branches  from  the  great  cardiac  plexus, 
forming  the  -posterior  pulmonary  plexus. 

Upon  the  oesophagus  the  two  nerves  divide  into  numerous  branches 
which  communicate  with  each  other  and  constitute  the  oesophageal 
plexus  which  completely  surrounds  the  cylinder  of  the  oesophagus, 
and  accompanies  it  to  the  cardiac  orifice  of  the  stomach. 

The  Gastric  branches  are  the  terminal  filaments  of  the  two  pneu- 
mogastric nerves ;  they  are  spread  out  upon  the  anterior  and  poste- 
rior surfaces  of  the  stomach,  and  are  likewise  distributed  to  the 
omentum,  spleen,  pancreas,  liver,  and  gall-bladder,  and  communi- 
cate, particularly  the  right  nerve,  with  the  solar  plexus. 

The  Spinal  Accessory  Nerve  arises  by  several  filaments  from 
the  respiratory  tract  as  low  down  as  the  fourth  or  fifth  cervical 
nerve,  and  ascends  behind  the  Hgamentum  denticulatum,  and  between 
the  anterior  and  posterior  roots  of  the  spinal  nerves,  to  the  foramen 
lacerum  posterius.  It  communicates  in  its  course  with  the  posterior 
root  of  the  first  cervical  nerve,  and  soon  becomes  applied  against 
the  ganglion  of  the  pneumogastric  and  enclosed  in  the  same  canal 
of  dura  mater.  In  the  jugular  fossa  it  divides  into  two  branches  ; 
the  smaller  joins  the  pneumogastric  immediately  below  the  superior 
ganglion,  and  contributes  to  the  formation  of  the  pharyngeal  nerve  ; 
while  the  larger  or  true  continuation  of  the  nerve  passes  backwards 
behind  the  internal  jugular  vein,  and  descends  obliquely  to  the  upper 
part  of  the  sterno-mastoid  muscle.  It  then  pierces  the  sterno-mas- 
toid  and  passes  obliquely  across  the  neck,  communicating  with  the 


398  FIFTH  PAIR TRIFACIAL. 

cervical  nerves,  and  is  distributed  to  the  trapezius.  The  spinal  ac- 
cessory sends  numerous  branches  to  the  sterno-mastoid  in  its  pas- 
sage through  that  muscle ;  its  branches  to  the  trapezius  may  be 
traced  to  the  lower  border  of  that  muscle. 

The  pneumogastric  and  spinal  accessory  nerves  together  resemble 
a  spinal  nerve,  the  former  representing  the  posterior  root  with  its 
ganglion,  and  the  latter  an  anterior  root. 

5th  pair.  Trifacial  (trigeminus). — This  nerve  is  analogous  to  the 
spinal  nerves  in  its  origin  by  two  roots,  from  the  anterior  and  poste- 
rior columns  of  the  spinal  cord,  and  in  the  existence  of  a  ganglion 
on  the  posterior  root.  Hence  it  ranges  with  the  spinal  nerves,  and 
is  considered  as  the  cranial  spinal  nerve. 

It  arises*  by  two  roots  from  a  tract  of  yellowish  white  matter 
situated  in  front  of  the  floor  of  the  fourth  ventricle  and  the  orio-in  of 
the  auditory  nerve,  and  behind  the  crus  cerebeUi.  This  tract  divides 
inferiorly  into  two  fasciculi  which  may  be  traced  downwards  into 
the  spinal  cord,  one  being  continuous  with  the  fibres  of  the  anterior 
column,  the  other  with  the  posterior  column.  Proceeding  from  this 
origin  the  two  roots  of  the  nerve  pass  forward,  and  issue  from  the 
brain  upon  the  anterior  part  of  the  crus  cerebelli,  where  they  are 
separated  by  a  slight  interval.  The  anterior  is  much  smaller  than 
the  posterior,  and  the  two  together  constitute  the  fifth  nerve,  which 
in  this  situation  consists  of  seventy  to  a  hundred  filaments  held 
together  by  pia  mater.  The  nerve  then  passes  through  an  oval 
opening  in  the  border  of  the  tentorium,  near  to  the  extremity  of  the 
petrous  bone,  and  spreads  out  into  a  large  semilunar  ganghon — the 
Casserian.  If  the  ganglion  be  turned  over,  it  will  be  seen  that  the 
anterior  root  lies  against  its  under  surface  without  having  any  con- 
nexion with  it,  and  may  be  followed  onwards  to  the  inferior  maxil- 
lary nerve.  The  Casserian  ganglion  divides  into  three  branches, 
the  ophthalmic,  superior  maxillary,  and  inferior  maxillary. 

The  Ophthalmic  Nerve  is  a  short  trunk,  being  not  more  than 
three  quarters  of  an  inch  in  length ;  it  arises  from  the  upper  angle  of 
the  Casserian  ganglion,  beneath  the  dura  mater,  and  passes  forwards 
through  the  outer  wall  of  the  cavernous  sinus,  lying  externally  to 
the  other  nerves:  it  divides  into  three  branches.  Previously  to  its 
division  it  receives  several  filaments  from  the  carotid  plexus,  and 
gives  off  a  small  recurrent  nerve,  that  passes  backwards  with  the 
recurrent  branch  of  the  fourth  nerve  between  the  two  layers  of  the 
tentorium  to  the  lining  membrane  of  the  lateral  sinus. 

The  Branches  of  the  ophthalmic  nerve  are,  the — 

Frontal, 
Lachrymal, 

Nasal. 


*  I  have  adopted  llic  origin  of  this  nerve,  given  by  Dr.  Alcock,  of  Dubhn,  as  the 
result  of  Ills  dissections,  in  llio  f"yclopa;dia  of  Anatomy  and  Physiology.  Mr.  Mayo 
also  traces  the  anterior  root  of  tlic  nerve  to  a  .similar  origin. 


BRANCHES  OF  THE  TRIFACIAL.  399 

The  Frontal  nerve  mounts  above  the  levator  palpebrse,  and  runs 
forward,  resting  upon  that  muscle,  to  the  supra-orbital  foramen, 
through  which  it  escapes  upon  the  forehead,  and  supplies  the  mus- 
cles and  integument  of  that  region. 

It  gives  off  one  small  branch,  the  supra-trochlear,  which  passes 
inwards  above  the  pulley  of  the  superior  oblique  muscle,  and  ascends 
along  the  middle  line  of  the  forehead,  distributing  filaments  to  the 
muscles  and  integument  at  the  inner  angle  of  the  eye  and  root  of  the 
nose. 

The  Lachrymal  nerve,  the  smallest  of  the  three  branches  of  the 
ophthalmic,  receives  a  filament  from  the  fourth  nerve  in  the  caver- 
nous sinus,  and  passes  outwards  along  the  upper  border  of  the  exter- 
nal rectus  muscle  to  the  lachrymal  gland,  where  it  divides  into  two 
branches.  The  superior  branch  passes  over  the  gland  and  through 
a  foramen  in  the  malar  bone,  and  is  distributed  upon  the  temple  and 
cheek,  communicating  with  the  temporo-malar  and  facial  nerves. 
The  inferior  branch  supplies  the  lower  surface  of  the  gland,  and  ter- 
minates in  the  integument  of  the  upper  lid  communicating  with  the 
facial  nerve. 

The  Nasal  nerve  passes  forwards  between  the  two  heads  of  the 
external  rectus  muscle,  crosses  the  optic  nerve  in  company  with  the 
ophthalmic  artery,  and  enters  the  anterior  ethmoidal  foramen  imme- 
diately above  the  internal  rectus.  It  then  traverses  the  upper  part 
of  the  ethmoid  bone  to  the  cribriform  plate,  and  passes  downwards 
through  the  slit-like  opening  by  the  side  of  the  crista  galh  into  the 
nose,  where  it  divides  into  two  branches — an  internal  branch  supply- 
ing the  mucous  membrane,  near  the  anterior  openings  of  the  nares; 
and  an  external  branch  which  passes  between  the  fibro-cartilages, 
and  is  distributed  to  the  integument  at  the  extremity  of  the  nose. 

The  Branches  of  the  nasal  nerve  within  the  orbit  are,  the  gangli- 
onic, ciliary,  and  infra-trochlear;  in  the  nose  it  gives  off  one  or  two 
filaments  to  the  anterior  ethmoidal  cells  and  frontal  sinus.  The 
ganglionic  branch  passes  obliquely  forwards  to  the  superior  angle  of 
the  ciliary  ganglion,  forming  its  superior  or  long  root.  The  ciliary 
branches  are  two  or  three  filaments  which  are  given  off  by  the  nasal 
as  it  crosses  the  optic  nerve.  They  pierce  the  posterior  part  of  the 
sclerotic,  and  pass  between  that  tunic  and  the  choroid  to  be  distri- 
buted to  the  iris.  The  infra-trochlear  is  given  off"  just  as  the  nerve 
is  about  to  enter  the  anterior  ethmoidal  foramen.  It  passes  along 
the  superior  border  of  the  internal  rectus  to  the  inner  angle  of  the 
eye,  where  it  communicates  with  the  supra-trochlear  nerve,  and 
supplies  the  lachrymal  sac,  caruncula  lachrymalis,  conjunctiva,  and 
inner  angle  of  the  orbit. 

The  Superior  Maxillary  Nerve  proceeds  from  the  middle  of  the 
Casscrian  ganglion ;  it  passes  forwards  through  the  foramen  rotun- 
dum,  crosses  the  spheno-maxillary  fossa,  and  enters  the  canal  in  the 
floor  of  the  orbit,  along  which  it  runs  to  the  infra-orbital  foramen. 
Emerging  on  the  face,  beneath  the  levator  labii  supcrioris  muscle, 
it  divides  into  a  leash  of  branches,  whicli  are  distributed  to  the 


400 


FIFTH  PAIR  OF  NERVES BRANCHES. 


muscles  and  integument  of  tlie  cheek,  forming  a  plexus  with  the 
facial  nerve. 

Fiff.  131.* 


The  Branches  of  the  superior  maxillary  nerve  are  divisible  into 
three  groups: — 1.  Those  which  are  given  off  in  the  spheno-maxil- 
lary  fossa.  2.  Those  in  the  infra-orbital  canal ;  and  3.  Those  on 
the  face.     They  may  be  thus  arranged : — 


Splieno-mazillary  fossa, 


Orbital. 

Two  from  Meckel's  ganglion,t 

Posterior  dental. 


*  A  diagram,  showing  the  fifth  pair  of  nerves  with  its  branches.  1 .  The  origin  of 
the  nerve  by  two  roots.  2.  Tlie  nerve  escaping  from  the  crus  cerebelli.  3,  Tin;  Cas- 
serian  ganglion.  4.  Its  ophthahnic  division.  5.  The  frontal  nerve,  giving  off  the 
supra-trociilcar  branch,  and  escaping  on  the  forehead  through  the  supra-orbital  foramen, 
6.  The  laclirymal  nerve.  7.  The  nasal  nerve,  passing  at  8  througli  the  anterior 
ethmoidal  foramen,  and  giving  off  the  infra-trochlear  branch.  9.  The  communication 
of  the  nasal  nerve  with  the  ciliary  ganglion.  10.  A  small  portion  of  the  third  nerve 
with  which  the  ganglion  is  seen  communicating;  the  ganglion  gives  off  the  ciliary 
branches  from  its  anterior  aspect.  11.  The  superior  maxillary  nerve.  12.  Its  orbital 
branch.  13.  The  two  branches  communicating  with  Meckel's  ganglion;  the  three 
branches  given  off  from  the  lower  part  of  the  ganglion  are  the  posterior  palatine  nerves. 
14,  14.  The  superior  dental  nerves,  posterior,  middle,  and  anterior.  15.  The  infra- 
orbital branches  distributed  upon  the  cheek.  16.  The  inferior  maxillary  nerve.  17. 
Its  anterior  or  muscular  trunk.  18.  The  posterior  tnnik ;  tlie  two  divisions  are  sepa- 
rated by  an  arrow.  19.  The  gustatory  nerve.  20.  The  cliorda  tympani  joining  it  at 
an  acute  angle.  21.  The  submaxillary  ganglion.  22.  The  inferior  dental  nerve.  23. 
Its  mylo-hyoidcan  branch.  24.  The  auricular  nerve,  dividing  behind  the  articulation 
of  the  lower  jaw,  to  reunite  and  form  a  single  trunk.  25.  Its  branch  of  communication 
with  the  facial  nerve.     26.  Its  temporal  branch. 

t  We  now  encounter  a  different  mode  of  describing  the  nerves  from  that  which  has 
been  so  long  in  use;  for  whore  it  was  customary  to  describe  these  branches  as  branches 
of  the  fifth  pair  running  down  to  form  Meckel's  ganglion,  wc  now  find  them  described 
as  running  up  to  join  the  fifth  pair.  This  arises  from  the  belief  now  general  that  these 
ganglia  form  a  part  of  the  great  sympathetic,  and  the  student  will  find  their  description 
under  that  head. — G. 


SUPERIOR  AND  INFERIOR  MAXILLARY  NERVES,  401 

T  -p  ^     Lu  1  7  \  Middle  dental, 

Infra-orbital  canal,     .      j  Anterior  dental. 

On  the  face,      .     .     .       j  ^^f  c^^^' 
•^  (  Lutaneous. 

The  Orbital  branch*  enters  the  orbit  through  the  spheno-maxillary 
fissure,  and  divides  into  two  branches :  lachrymal.-f  which  ascends 
along  the  outer  wall  of  the  orbit  to  the  lachr\Tnal  gland,  and  com- 
municates with  the  lachr\Tnal  nerve :  temporo-malar'l  which  passes 
forwards  and  divides  into  two  branches :  one  piercing  the  malar 
bone,  is  distributed  to  the  integument  of  the  cheek,  communicating 
with  the  facial  nen-e;  the  other  escaping  through  the  outer  wall  of 
the  01-bit  supplies  the  temporal  muscle  and  integument  in  the  tempo- 
ral region,  and  communicates  with  the  temporal,  anterior  auricular, 
and  facial  nerve. 

The  Two  branches  from  Meckel's  ganglion  ascend  from  that  body- 
to  join  the  nerve,  as  it  crosses  the  spheno-maxillary  fossa. 

The  Posterior  dental  hranches  pass  through  small  foramina,  in  the 
posterior  surface  of  the  superior  maxillaiy-  bone,  and  supply  the  pos- 
terior teeth. 

The  Middle  and  anterior  denial  branches  descend  to  the  teeth  : 
the  former  beneath  the  lining  membrane  of  the  antrum,  the  latter 
through  distinct  canals  in  the  walls  of  the  bone. 

The  Muscular  and  cutaneous  branches  are  the  terminating  fila- 
ments of  the  nerve ;  they  supply  the  muscles  and  integument  of  the 
cheek,  and  form  an  intricate  plexus  with  branches  of  the  facial 
nerve. 

The  LvFERioR  Maxillary  Nerve  proceeds  from  the  inferior  angle 
of  the  Casserian  ganglion ;  it  is  the  largest  of  the  three  divisions  of 
the  fifth  nerve,  and  is  augmented  in  size  by  the  anterior  or  motor 
root,  which  passes  behind  the  ganglion,  and  unites  ^"ith  the  inferior 
maxillary  as  it  escapes  through  the  foramen  ovale.  Emerging  at 
the  foramen  ovale  the  nerve  diWdes  into  two  trunks,  external  and  in- 
ternal, which  are  separated  from  each  other  by  the  external  pter}-- 
goid  muscle. 

The  External  trunk,  into  which  may  be  traced  the  whole  of  the 
motor  root,  immediately  di\-ides  into  five  branches  which  are  dis- 
tributed to  the  muscles  of  the  temporo-maxillary  region ;  they 
are — 

The  Masseteric,  which  crosses  the  sigmoid  notch  with  the  mas- 
seteric artery  to  the  masseter  muscle.  It  sends  a  small  branch  to 
the  temporal  muscle,  and  a  filament  to  the  temporo-maxillary  arti- 
culation. 

Temjporal ;  two  branches  passing  between  the  upper  border  of 
the  external  pterygoid  muscle  and  the  temporal  bone  to  the  tem- 
poral muscle.    Two  or  three  filaments  from  these  nen^es  pierce  the 

*  Nervus  subcutaneus  maUz  of  other  anatomists. — G, 

+  The  malar  branch. — G.  X  The  temporal  branch. — G. 

51 


402  GUSTATORY  NERVE INFERIOR  DENTAL  NERVE. 

temporal  fascia,  and  communicate  with  the  lachrymal,  temporo- 
malar,  auricular  and  facial  nerve. 

Buccal  f"  a  large  branch  which  pierces  the  fibres  of  the  external 
pterygoid,  to  reach  the  buccinator  muscle.  This  nerve  sends  fila- 
ments to  the  temporal  and  external  pterygoid  muscle,  to  the  mucous 
membrane  and  integument  of  the  cheek,  and  communicates  with  the 
facial  nerve. 

Internal  'pterygoid ;  a  long  and  slender  branch,  which  passes  in- 
wards to  the  internal  pterygoid  muscle.  This  nerve  is  remarkable 
from  its  connexion  with  the  otic  ganglion,  to  which  it  is  closely 
attached. 

The  Internal  trunk  divides  into  three  branches — 

Gustatory, 
Inferior  dental, 
Anterior  auricular. 

The  Gustatory  Nerve  descends  between  the  two  pterygoid 
muscles  to  the  side  of  the  tongue,  where  it  becomes  flattened,  and 
divides  into  numerous  filaments,  which  are  distributed  to  the  papillag 
and  mucous  membrane. 

Relations. — It  lies  at  first  between  the  external  pterygoid  muscle 
and  the  pharynx,  next  between  the  two  pterygoid  muscles,  then  be- 
tween the  internal  pterygoid  and  ramus  of  the  jaw,  and  between 
the  stylo-glossus  muscle  and  the  submaxillary  gland;  lastly,  it  runs 
along  the  side  of  the  tongue,  resting  upon  the  hyo-glossus  muscle, 
and  covered  in  by  the  mylo-hyoideus  and  mucous  membrane. 

The  gustatory  nerve,  while  between  the  two  pterygoid  muscles, 
receives  a  branch  from  the  inferior  dental ;  lower  down  it  is  joined 
at  an  acute  angle  by  the  chorda  tympani  which  passes  downwards 
in  the  sheath  of  the  gustatory  to  the  submaxillary  gland,  where  it 
unites  with  the  submaxillary  ganglion.  On  the  hyo-glossus  muscle 
some  branches  of  communication  are  sent  to  the  hypoglossal,  and 
in  the  course  of  the  nerve  several  small  branches  to  the  mucous 
membrane  of  the  fauces,  and  to  the  tonsils,  and  numerous  filaments 
to  the  submaxillary  gland. 

The  Inferior  Dental  Nerve  passes  downwards  with  the  inferior 
dental  artery,  at  first  between  the  two  pterygoid  muscles,  and  then 
between  the  internal  lateral  ligament  and  the  ramus  of  the  lower  jaw, 
to  the  dental  foramen.  It  then  runs  along  the  canal  in  the  inferior 
maxillary  bone,  distributing  branches  to  the  teeth,  and  divides  into 
two  branches,  incisive  and  mental.  The  incisive  branch  passes  for- 
wards to  supply  the  incisive  teeth :  and  the  mental  branch  escapes 
through  the  mental  foramen,  to  be  distributed  to  the  muscles,  and 
integument  of  the  chin,  and  to  communicate  with  the  facial  nerve. 

It  gives  off  but  one  branch,  the  mylo-liyoidean,  wliich  leaves  the 

*  The  name  buceal  is  usually  applied  to  the  central  branches  from  the  pes  anserinus 
of  the  facial  nerve. — G. 


AURICULAR  NERVE SPINAL  NERVES.  403 

nerve  just  as  it  is  about  to  enter  the  dental  foramen.  Tliis  branch 
pierces  the  insertion  of  the  internal  lateral  ligament,  and  descends 
along  a  groove  in  the  bone  to  the  superior  surface  of  the  mylo-hyoid 
muscle,  to  which  it  is  distributed. 

The  ApfTERioR  Auricular  Nerve  passes  directly  backwards  be- 
hind the  articulation  of  the  lower  jaw,  against  which  it  rests.  In 
this  situation  it  divides  into  two  branches,  which  reunite,  and  form 
a  kind  of  plexus.  From  the  plexus  two  branches  are  given  off — 
ascending  and  descending.  The  ascending  or  temporal  branch* 
sends  a  considerable  branch  of  communication  to  the  facial  nerve, 
and  then  ascends  in  front  of  the  ear  to  the  temporal  region,  upon 
which  it  is  distributed  in  company  with  the  branches  of  the  temporal 
artery.  In  its  course  it  sends  filaments  to  the  temporo-maxillary 
articulation,  to  the  pinna  and  meatus  of  the  ear,  and  to  the  integu- 
ment in  the  temporal  region.  It  communicates  on  the  temple  with 
branches  of  the  facial,  supra-orbital,  lachrymal,  and  temporo-malar 
nerve.  The  descending  branch  enters  the  parotid  gland,  to  which 
it  sends  numerous  branches ;  it  communicates  with  the  inferior 
dental  and  auricularis  magnus  nerve,  and  supplies  the  external  ear 
and  the  temporo-maxillary  articulation. 


SPINAL  NERVES. 

There  are  thirty-one  pairs  of  spinal  nerves,  each  arising  by  two 
roots,  an  anterior  or  motor  root,  and  a  posterior  or  sensitive  root. 

The  anterior  roots  arise  from  a  narrow  white  line  upon  the  ante- 
rior columns  of  the  spinal  cord,  and  gradually  approach  towards  the 
anterior  longitudinal  sulcus  as  they  descend. 

The  posterior  roots,  more  regular  than  the  anterior,  arise  from  a 
Fiarrow  gray  band  formed  by  the  internal  gray  substance  of  the 
cord.  They  are  larger,  and  the  filaments  of  the  origin  more  nume- 
rous than  those  of  the  anterior  roots.  A  ganglion  is  found  upon 
each  of  the  posterior  roots  in  the  intervertebral  foramina.  The 
first  cervical  nerve  forms  an  exception  to  these  characters.  Its 
posterior  root  is  smaller  than  the  anterior;  there  is  frequently 
no  ganglion  upon  it,  and  it  often  joins  in  the  whole  or  in  part  with 
the  spinal  accessory  nerve. 

After  the  formation  of  the  ganglion  the  two  roots  unite,  and  con- 
stitute a  spinal  nerve,  which  escapes  through  the  intervertebral  fora- 
men, and  divides  into  an  anterior  branch,  for  the  supply  of  the  front 
half  of  the  body,  and  a  posterior  branch,  for  the  posterior  half. 

The  anterior  branches,  with  the  exception  of  the  two  first  cervical 
nerves,  are  larger  than  the  posterior;  an  arrangement  which  is 
proportioned  to  the  larger  extent  of  surface  they  are  required  to 
supply. 

*  This  is  usually  called  the  superficial  temporal  nerve. — G. 


404  ANTERIOR  CERVICAL  NERVES. 

The  Spinal  nerves  are  divided  into — 

Cervical  .         .         .         .         8  pairs 

Dorsal  .         .         .         .12 

Lumbar  ....         5 

Sacral  ....         6 

The  Cervical  nerves  pass  off  transversely  from  the  spinal  cord ; 
the  dorsal  are  oblique  in  their  direction ;  and  the  lumbar  vertical, 
and  form  the  large  assemblage  of  nerves  at  the  termination  of  the 
cord  called  cauda  equina. 

The  Cervical  Nerves  increase  in  size  from  above  downv^'^ards  ; 
the  first  (sub-occipital)  passes  out  of  the  spinal  canal  between  the 
occipital  bone  and  the  atlas ;  and  the  last,  betw^een  the  last  cervical 
and  first  dorsal  vertebra.  Each  nerve,  at  its  escape  from  the  inter- 
vertebral foramen,  divides  into  an  anterior  and  a  posterior  branch. 
The  anterior  branches  of  the  four  upper  cervical  nerves  form  the 
cervical  plexus ;  the  posterior  branches,  the  posterior  cervical  plexus. 

The  anterior  branches  of  the  four  inferior  cervical  together  with 
the  first  dorsal  form  the  brachial  plexus. 

Anterior  cervical  nerves. — The  Anterior  branch  of  the  first  cervical 
nerve  escapes  from  the  vertebral  canal  through  the  groove  upon  the 
posterior  arch  of  the  atlas  which  supports  the  vertebral  artery, 
beneath  which  it  lies.  It  then  descends  in  front  of  the  transverse 
process  of  the  atlas,  and  forms  a  loop  by  communicating  with  an 
ascending  branch  of  the  second  nerve. 

The  Anterior  branch  of  the  second  cervical  nerve  divides  into  three 
branches  at  its  exit  from  the  intervertebral  foramen  between  the 
atlas  and  axis,  viz.  an  ascending  branch,  which  completes  the  arch 
of  communication  with  the  first  nerve;  and  two  descending  branches, 
which  communicate  with  the  third  nerve. 

The  Anterior  branch  of  the  tliird  cervical  nerve,  double  the  size 
of  the  preceding,  divides  at  its  exit  from  the  intervertebral  foramen 
into  numerous  branches,  some  of  which  communicate  and  form 
loops  and  anastomoses  with  the  second,  and  others  with  the  fourth 
nerve. 

The  Anterior  branch  of  the  fourth  cervical  nerve,  of  the  same  size 
with  the  preceding,  communicates  by  anastomosis  with  the  third, 
and  sends  a  small  branch  downwards  to  the  fifth  nerve.  Its  prin- 
cipal branches  pass  downwards  and  outwards  across  the  posterior 
triangle  of  the  neck,  towards  the  clavicle  and  acromion. 

The  Cervical  Plexus  is  constituted  by  the  loops  of  communica- 
tion, and  by  the  anastomoses  which  take  place  between  the  anterior 
branches  of  the  four  first  cervical  nerves.  The  plexus  rests  upon 
the  levator  anguli  scapulae,  posterior  scalenus,  and  splenius  muscle, 
and  is  covered  in  by  the  sterno-mastoid  and  platysma. 

The  branches  of  the  cervical  plexus  may  be  arranged  into  three 
groups,  superficial  ascending,  superficial  descending;  and  deep — 


CERVICAL  BKANCHES.  405 


(  Superficialis  colli, 
Ascending.     <  Auricularis  magnus, 
a        n  ■  ii  i  Occipitalis  minor. 

Superficial  <^  \  A.rn.^i«w 


Deep. 


rx  J-         »  Acromiales, 

Descending.    |  ciaviculares. 

Communicating  branches, 
Muscular, 
Communicans  noni. 
Phrenic. 


The  Superficialis  colli  is  formed  by  communicating  branches  from 
the  second  and  third  cervical  nerves ;  it  curves  around  the  posterior 
border  of  the  sterno-mastoid  and  crosses  obliquely  behind  the  ex- 
ternal jugular  vein  to  the  anterior  border  of  that  muscle,  where  it 
divides  into  an  ascending  and  a  descending  branch  ;  the  descending 
branch  is  distributed  to  the  integument  on  the  side  and  front  of  the 
neck ;  the  ascending  branch  passes  upwards  to  the  submaxillary 
region,  and  divides  into  four  or  five  filaments,  some  of  which  pierce 
the  platysma  myoides  and  supply  the  integument  as  high  up  as  the 
chin  and  the  lower  part  of  the  face,  while  others  form  a  plexus  with 
the  descending  branches  of  the  facial  nerve  beneath  the  platysma. 
One  or  two  filaments  from  this  nerve  accompany  the  external  jugular 
vein. 

The  Auricularis  magnus  also  proceeds  from  the  second  and  third 
cervical  nerve ;  it  curves  around  the  posterior  border  of  the  sterno- 
mastoid  and  ascends  upon  that  muscle,  lying  parallel  with  the  ex- 
ternal jugular  vein  to  the  parotid  gland,  where  it  divides  into  a 
superficial  and  deep  branch.  The  superficial  branch  is  distributed 
to  the  integument  over  the  parotid  gland,  and  to  the  anterior  surface 
of  the  external  ear.  Therieep  branch  pierces  the  parotid  gland  and 
crosses  the  mastoid  process,  where  it  divides  into  branches  which 
supply  the  posterior  part  of  the  pinna  and  the  integument  of  the  side 
of  the  head.  Previously  to  its  division  the  auricularis  magnus  nerve 
sends  oflf  several  facial  branches  which  are  distributed  to  the  cheek. 
The  terminal  branches  of  this  nerve  communicate  with  branches 
of  the  anterior  auricular,  the  facial,  and  the  occipitalis  major 
nerve. 

The  Occipitalis  minor  arises  from  the  second  cervical  nerve ;  it 
curves  around  the  posterior  border  of  the  sterno-mastoid  above  the 
preceding  and  ascends  upon  that  muscle,  parallel  with  its  posterior 
border,  to  the  lateral  and  posterior  side  of  the  head.  It  is  distributed 
to  the  integument  in  this  region. 

The  Acromiales  and  Ciaviculares  are  two  or  three  large  nerves 
which  descend  from  the  plexus  and  divide  into  numerous  branches 
which  pass  downwards  over  the  clavicle,  and  are  distributed  to  the 
integument  of  the  upper  and  anterior  part  of  the  chest  from  the 
sternum  to  the  shoulder. 

The  Communicating  branches  are  filaments  which  arise  from  the 
loop  between  the  first  and  second  cervical  nerve,  and  pass  inwards 


406  POSTERIOR  CERVICAL  PLEXUS. 

to  communicate  with  the  sympathetic,  the  pneumogastric,  and  the 
lingual  nerve.  The  three  first  cervical  nerves  send  branches  to  the 
first  cervical  ganglion  ;  the  fourth  sends  a  branch  to  the  trunk  of 
the  sympathetic,  or  to  the  middle  cervical  ganglion.  From  the 
second  cervical  nerve  a  large  branch  is  given  off  which  goes  to  join 
the  spinal  accessory  nerve. 

The  JSluscular  branches  proceed  from  the  third  and  fourth  cervical 
nerves;  they  are  distributed  to  the  trapezius, levator  anguli  scapula;, 
and  rhomboidei  muscles.  From  the  second  cervical  nerve  a  small 
muscular  branch  is  sent  to  the  rectus  anticus  major. 

The  Communicans  noni  is  a  long  slender  branch  formed  by  fila- 
ments from  the  first,  second,  and  third  cervical  nerves  :  it  descends 
upon  the  outer  side  of  the  internal  jugular  vein,  and  forms  a  loop 
with  the  descendens  noni  over  the  sheath  of  the  carotid  vessels. 

The  Phrenic  nerve  is  formed  by  filaments  from  the  third,  fourth, 
and  fifth  cervical  nerves,  receiving  also  a  branch  from  the  sympa- 
thetic. It  descends  to  the  root  of  the  neclv,  resting  upon  the  scalenus 
anticus  muscle,  then  crosses  the  first  portion  of  the  subclavian 
artery,  and  enters  the  chest  between  it  and  the  subclavian  vein. 
Within  the  chest  it  passes  through  the  middle  mediastinum,  between 
the  pleura  and  pericardium  to  the  diaphragm  to  which  it  is  distri- 
buted, and  communicates  in  the  abdomen  with  the  phrenic  and 
solar  plexus,  and  on  the  right  side  with  the  hepatic  plexus.  The 
left  phrenic  nerve  is  rather  longer  than  the  right,  from  the  inclina- 
tion of  the  heart  to  the  left  side. 

Posterior  cervical  nerves. — The  posterior  division  of  the  first  cer- 
vical nerve  (sub-occipital),  larger  than  the  anterior,  escapes  from 
the  vertebral  canal  through  the  opening  for  the  vertebral  artery, 
lying  posteriorly  to  that  vessel,  and  emerges  into  the  triangular 
space  formed  by  the  rectus  posticus  major,  obliquus  superior,  and 
obliquus  inferior.  It  is  distributed  to  the  recti  and  obliqui  muscles, 
and  sends  one  or  two  filaments  downwards  to  communicate  with 
the  second  cervical  nerve.  The  posterior  branch  of  the  second  cer- 
vical nerve  is  three  or  four  times  greater  than  the  anterior  branch, 
and  is  larger  than  the  other  posterior  cervical  nerves.  The  poste- 
rior branch  of  the  third  cervical  nerve  is  smaller  than  the  preceding, 
but  larger  than  the  fourth  ;  and  the  other  posterior  cervical  nerves 
go  on  progressively  decreasing  to  the  seventh. 

Posterior  Cervical  Plexus. — This  plexus  is  constituted  by  the 
succession  of  anastomosing  loops  and  communications  which  pass 
between  the  posterior  branches  of  the  first,  second,  and  third  cer- 
vical nerves.  It  is  situated  between  the  complexus  and  semispinaHs 
colli,  and  its  branches  are  the — 

Musculo-c  utaneous. 
Occipitalis  major. 

The  Musculo-cutaneous  branches  pass  inwards  between  the  com- 
plexus and  semispinalis  colli  to  the  ligamenlum  nuchse,  distributing 


BRACHIAL  PLEXUS.  407 

muscular  filaments  in  their  course.  They  then  pierce  the  aponeu- 
rosis of  the  trapezius  and  become  subcut^aneous,  sending  branches 
outwards  to  supply  the  integument  of  the  posterior  aspect  of  the 
neck,  and  upwards  to  the  posterior  region  of  the  scalp. 

The  Occipitalis  major  is  the  direct  continuation  of  the  second 
cervical  nerve ;  it  ascends  obliquely  inwards,  between  the  obliquus 
inferior  and  complexus,  pierces  the  complexus  and  trapezius,  after 
passing  for  a  short  distance  between  them,  and  ascends  upon  the 
posterior  aspect  of  the  head  between  the  integument  and  occipito- 
frontalis,  in  company  with  the  occipital  artery.  The  occipitalis 
major  sends  numerous  branches  to  the  muscles  of  the  neck,  and  is 
distributed  to  the  integument  of  the  scalp,  as  far  forwards  as  the 
middle  of  the  vertex  of  the  head. 

The  Posterior  branches  of  the  fourth,  fifth,  sixth,  seventh,  and 
eighth  nerves  pass  inwards  between  the  muscles  of  the  back  in  the 
cervical  and  upper  part  of  the  dorsal  region,  and  reaching  the  sur- 
face near  to  the  middle  line  are  reflected  outwards  to  be  distributed 
to  the  integument.  The  fourth  and  fifth  are  nearly  transverse  in 
their  course,  and  lie  between  the  semispinalis  colli  and  complexus. 
The  sixth,  seventh,  and  eighth  are  directed  nearly  vertically  down- 
wards ;  they  pierce  the  aponeurosis  of  origin  of  the  splenius  and 
trapezius. 

BRACmAL  PLEXUS. 

The  Brachial  OY  axillary  plexus  of  nerves  is  formed  by  communi- 
cations between  the  anterior  branches  of  the  four  last  cervical  and 
first  dorsal  nerve.  These  nerves  are  all  similar  in  size,  and  their 
mode  of  disposition  in  the  formation  of  the  plexus  is  the  following: 
the  fifth  and  sixth  nerves  unite  to  form  a  common  trunk,  which 
soon  divides  into  two  branches  ;  the  last  cervical  and  first  dorsal 
also  unite  immediately  upon  their  exit  from  the  intervertebral  fora- 
mina, and  the  common  trunk  resulting  from  their  union  after  a  short 
course  also  divides  into  two  branches ;  the  seventh  nerve  passes 
outwards  between  the  common  trunks  of  the  two  preceding,  and 
opposite  the  clavicle  divides  into  a  superior  branch  which  unites  with 
the  inferior  division  of  the  superior  trunk,  and  an  inferior  branch 
which  communicates  with  the  superior  division  of  the  inferior  trunk ; 
from  these  divisions  and  communications  the  brachial  plexus  results. 
The  brachial  plexus  communicates  with  the  cervical  plexus  by 
means  of  a  branch  sent  from  the  fourth  to  the  fifth  nerve,  and  by 
the  inferior  branch  of  origin  of  the  phrenic  nerve.  The  plexus  is 
broad  in  the  neck,  narrow  as  it  descends  into  the  axilla,  and  again 
enlarges  at  its  lower  part  where  it  divides  into  its  six  terminal 
branches. 

Relations. — The  brachial  plexus  is  in  relation  in  the  neck  with 
the  two  scaleni  muscles,  between  which  its  nerves  issue;  lower  down 
it  is  placed  between  the  clavicle  and  subclavius  muscle  above,  and 
the  first  rib  and  first  serration  of  the  serratus  magnus  muscle  below. 


408  BRACHIAL  PLEXUS BRANCHES. 

In  the  axilla,  it  is  situated  at  first  to  the  outer  side  and  then  behind 
the  axillary  artery,  resting  by  its  outer  border  against  the  tendon 
of  the  subscapularis  muscle.  At  this  point  it  completely  surrounds 
the  artery  by  means  of  the  two  cords  which  are  sent  oft'  to  form  the 
median  nerve. 

Its  Branches  may  be  arranged  into  two  groups,  humeral  and  de- 
scending,— 

Humeral  Branches.  Descending  Branches. 

Superior  muscular,  External  cutaneous, 

Short  thoracic,  Internal  cutaneous, 

Long  thoracic.  Lesser  internal  cutaneous. 

Supra-scapular,  Median, 

Subscapular,  Ulnar, 

Inferior  muscular.  Musculo-spiral, 

Circumflex. 

The  superior  Muscular  nerves  are  several  large  branches  which 
are  given  off  by  the  fifth  cervical  nerve  above  the  clavicle ;  they 
are — a  subclavian  branch  to  the  subclavius  muscle,  which  usually 
sends  a  communicating  filament  to  the  phrenic  nerve  ; — a  rhomboid 
branch  to  the  rhomboidei  muscles;  and  frequently  an  angular  branch 
to  the  levator  anguli  scapulffi. 

The  Short  thoracic  nerves  are  two  in  number ;  they  arise  from  the 
brachial  plexus  at  a  point  parallel  with  the  clavicle,  and  are  divisible 
into  an  anterior  and  a  posterior  branch.  The  anterior  branch  passes 
forwards  between  the  subclavius  muscle  and  the  subclavian  vein, 
and  is  distributed  to  the  pectoralis  major  muscle,  entering  it  by  its 
costal  surface.  In  its  course  it  gives  off  a  branch  which  forms  a 
loop  of  communication  with  the  posterior  branch.  The  posterior 
branch  passes  forward  beneath  the  axillary  arteiy  and  unites  with 
the  communicating  branch  of  the  preceding  to  form  a  loop,  from 
which  numerous  branches  are  given  ofl'  to  the  pectoraUs  major  and 
pectoralis  minor. 

The  Long  thoracic  nerve  (external  respiratory  of  Bell)  is  a  long 
and  remarkable  branch  arising  from  the  fourth  and  fifth  cervical 
nerves,  immediately  after  their  escape  from  the  intervertebral  fora- 
mina. It  passes  down  behind  the  plexus  and  axillary  vessels,  resting 
on  the  scalenus  posticus  muscle ;  it  then  descends  along  the  side  of 
the  chest  upon  the  serratus  magnus  muscle  to  its  lowest  serration. 
It  sends  numerous  filaments  to  this  muscle  in  its  course. 

The  Supra-scapular  nerve  arises  above  the  clavicle  from  the  fifth 
cervical  nerve  and  descends  obliquely  outwards  to  the  supra-scapu- 
lar notch ;  it  then  passes  through  the  notch,  crosses  the  supra-spinous 
fossa  beneath  the  supra-spinatus  muscle,  and  passing  in  front  of  the 
concave  margin  of  the  spine  of  the  scapula  enters  the  infra-spinous 
fossa.  It  is '^distributed  to  the  supra-spinatus  and  infra-spinatus 
muscle. 

The  Subscapular  nerves  are  three  or  four  in  number;  of  which 
one  arises  from  the  brachial  plexus  above  the  clavicle,  and  the 


EXTERNAL  CUTANEOUS  NEKVE. 


409 


the  axilla.     They  are  distributed  to  the   subscapularis 


others  in 
muscle. 

The  terminal  branches  of  the  plexus  are 
arranged  in  the  following  order :  the  external 
cutaneous,  and  one  head  of  the  median  to  the 
outer  side  of  the  artery ;  the  other  head  of  the 
median,  internal  cutaneous,  and  ulnar,  upon 
its  inner  side;  and  the  circumflex  and  musculo- 
spiral  behind. 

The  External  Cutaneous  Nerve  (mus- 
culo-cutaneous,  perforans  Casserii)  arises  from 
the  brachial  plexus  in  common  with  the  ex- 
ternal head  of  the  median;  it  pierces  the 
coraco-brachialis  muscle  and  passes  between 
the  biceps  and  brachialis  anticus,  to  the  outer 
side  of  the  bend  of  the  elbow,  where  it  perfo- 
rates the  fascia,  and  divides  into  an  external 
and  internal  branch. 

These  branches  pass  behind  the  median 
cephalic  vein  and  are  distributed  to  the  integu- 
ment upon  the  outer  side  of  the  fore-arm  as 
far  as  the  wrist,  communicating  with  the  in- 
ternal cutaneous  and  radial  nerves.  From  the 
internal  division  at  the  lower  third  of  the  fore- 
arm a  branch  is  given  off  which  accompanies 
the  radial  artery  to  the  wrist  and  supplies 
several  filaments  to  the  synovial  membranes 
of  the  wrist,  both  on  its  anterior  and  posterior 
aspect. 

The  Branches  of  the  external  cutaneous 
nerve  in  the  upper  arm  are  distributed  to  the 
coraco-brachialis,  biceps,  and  brachialis  anti- 
cus muscle. 

The  Internal  Cutaneous  Nerve  is  one  of 


Fig.  132.* 


*  The  Brachial  plexus  of  nerves  with  its  branches  and  their  distribution.  1.  The 
brachial  plexus.  2.  The  short  thoracic  nerves.  3.  The  long  thoracic  or  external 
respiratory  of  Bell.  4.  The  phrenic  nerve.  5.  The  supra-scapular  nerve.  6.  The 
subscapular  nerves.  7.  The  external  cutaneous  nerve.  8.  Tiie  point  at  which  it 
pierces  the  coraco-brachialis  muscle.  9.  The  internal  cutaneous  nerve  :  the  point  at 
which  it  pierces  the  deep  fascia.  10.  The  origin  of  the  median  nerve  by  two  heads. 
11.  The  bend  of  the  elbow  where  the  median  passes  between  the  two  heads  of  the 
pronator  radii  teres,  and  of  the  flexor  sublimis  digitorum.  12.  Its  muscular  branches. 
13.  Its  anterior  interosseous  branch.  14.  The  point  at  which  the  nerve  passes  beneath 
the  annular  ligament  and  divides  into  six  terminal  branches.  The  branch  which 
crosses  the  annular  ligament  is  the  superficial  palmar.  15.  The  ulnar  nerve  giving  off 
several  muscular  branches  to  the  triceps.  IG.  Tlie  point  at  which  it  passes  between 
the  two  heads  of  the  flexor  carpi  ulnaris.  17.  Its  dorsal  branch,  18.  The  termination 
of  tlic  nerve,  dividing  into  a  superficial  and  deep  palmar  branch.  19.  The  nmsculo- 
spiral  nerve.  20.  IVLuscular  branches.  21.  Spiral  cutaneous  nerve.  22.  The  posterior 
interosseous  nerve  piercing  the  supinator  brcvis  muscle.  23.  Tlic  radial  nerve.  The 
two  last  nerves  are  the  terminal  branclics  of  the  musculo-spiral.  24.  The  point  at 
which  the  radial  nerve  pierces  the  deep  fascia.     25.  The  circumflex  nerve. 

52  ' 


410  MEDIAN  ^•ERVE BRANCHES. 

the  internal  and  smallest  of  the  branches  of  the  axillary  plexus ;  it 
arises  from  the  plexus  in  common  with  the  ulnar  and  internal  head 
of  the  median,  and  passes  down  the  inner  side  of  the  arm  in  com- 
pany with  the  basilic  vein.  At  about  the  middle  of  the  arm  it  pierces 
the  deep  fascia  by  the  side  of  the  basilic  vein  and  divides  into  two 
branches,  anterior  and  posterior.  Each  of  these  branches  subdivides 
into  several  filaments,  which  are  distributed  to  the  integument  upon 
the  anterior  and  posterior  aspect  of  the  ulnar  border  of  the  fore-arm 
as  far  as  the  wrist.  At  the  bend  of  the  elbow  the  filaments  of  the 
anterior  branch  pass  in  front  of  the  median  basilic  vein,  and  some- 
times behind  that  vessel.  On  the  fore-arm  the  nervous  filaments 
communicate  with  the  external  cutaneous  and  with  the  ulnar  nerve. 

The  Lesser  Internal  Cutaneous  Nerve  or  nerve  of  Wrlsherg  is 
very  irregular  in  point  of  origin.  It  is  a  long  and  slender  nerve,  and 
usually  arises  from  the  common  trunk  of  the  last  cervical  and  first 
dorsal  nerve.  Passing  downwards  into  the  axillary  space  it  com- 
municates with  the  external  branch  of  the  first  intercosto-humeral 
nerve,  and  descends  upon  the  inner  side  of  the  internal  cutaneous 
nerve,  to  the  middle  of  the  posterior  aspect  of  the  upper  arm,  where 
it  pierces  the  fascia  and  is  distributed  to  the  integument  of  the  elbow, 
communicating  with  the  filaments  of  the  internal  cutaneous  and 
spiral  cutaneous.  In  its  course  it  gives  off  two  or  three  cutaneous 
filaments  to  the  integument  of  the  inner  and  anterior  aspect  of  the 
upper  arm. 

The  Median  Nerve  has  received  its  name  from  taking  a  course 
along  the  middle  of  the  arm  to  the  palm  of  the  hand;  it  is,  there- 
fore, intermediate  in  position,  betw^een  the  radial  and  ulnar  nerves. 
It  commences  by  two  heads,  which  embrace  the  axillary  artery ; 
lies  at  first  to  the  outer  side  of  the  brachial  artery,  which  it  crosses 
at  its  middle ;  and  descends  on  its  inner  side  to  the  bend  of  the  elbow. 
It  then  passes  between  the  two  heads  of  the  pronator  radii  teres  and 
flexor  sublimis  digitorum  muscles,  and  runs  down  the  fore-arm  be- 
tween the  flexor  sublimis  and  profundus,  and  beneath  the  annular 
ligament  into  the  palm  of  the  hand. 

The  branches  of  the  median  nerve  are, — 

Muscular,  Superficial  palmar, 

Anterior  interosseous,  Digital. 

The  Muscular  branches  are  given  off  by  the  nerve  at  the  bend  of 
the  elbow ;  they  are  distributed  to  all  the  muscles  on  the  anterior 
aspect  of  the  fore-arm,  with  the  exception  of  the  flexor  carpi  ulnaris, 
and  to  the  periosteum.  The  branch  to  the  pronator  radii  teres  sends 
off  reflected  branches  to  the  elbow-joint. 

The  Jlnterior  interosseous  is  a  large  branch  accompanying  the 
anterior  interosseous  artery,  and  supplying  the  deep  layer  of  muscles 
in  the  fore-arm.  It  passes  beneath  the  pronator  quadratus  muscle, 
and  ])icrccs  flic  interosseous  membrane  near  to  the  wrist.  On 
reaching  the  posterior   aspect  of  the  wrist  it  joins  a  large  and 


ULNAR  NERVE ERANCPIES.  411 

remarkable  ganglion,  which  gives  off  a  number  of  branches  for  the 
supply  of  the  joint. 

The  Superficial  falmar  h-anc/i  arises  from  the  median  nerve  at 
about  the  lower  fourth  of  the  fore-arm ;  it  crosses  the  annular  liga- 
ment, and  is  distributed  to  the  integument  over  the  ball  of  the 
thumb  and  in  the  palm  of  the  hand. 

The  median  nerve  at  its  termination  in  the  palm  of  the  ■  hand  is 
very  considerably  spread  out  and  flattened,  and  it  divides  into  six 
branches,  one  muscular  and  five  digital.  The  muscular  branch  is 
distributed  to  the  muscles  of  the  ball  of  the  thumb.  The  digital 
branches  are  thus  arranged  : — two  pass  outwards  to  the  thumb  ;  one 
to  the  radial  side  of  the  index  finger ;  one  subdivides  for  the  supply 
of  the  adjoining  sides  of  the  index  and  middle  fingers ;  and  the  re- 
maining one,  for  the  supply  of  the  adjoining  sides  of  the  middle  and 
ring  fingers.  The  digital  nerves  in  their  course  along  the  fingers  are 
situated  to  the  inner  side  of  the  digital  arteries.  Opposite  the  base  of 
the  first  phalanx  each  nerve  gives  off"  a  dorsal  branch  which  runs 
along  the  border  of  the  dorsum  of  the  finger.  Near  the  extremity  of 
the  finger  the  digital  nerve  divides  into  a  'palmar  and  a  dorscd  branch ; 
the  former  supplying  the  sentient  extremity  of  the  finger,  and  the 
latter  the  structures  around  and  beneath  the  nail.  The  digital 
nerve  maintains  no  communication  with  its  fellow  of  the  opposite 
side. 

The  Ulnar  Nerve  is  somewhat  smaller  than  the  median,  behind 
which  it  lies,  gradually  diverging  from  it  in  its  course.  It  arises  from 
the  brachial  plexus  in  common  with  the  internal  head  of  the  median 
and  the  internal  cutaneous  nerve,  and  runs  down  the  inner  side  of 
the  arm,  to  the  groove  between  the  internal  condyle  and  olecranon, 
resting  upon  the  internal  head  of  the  triceps,  and  accompanied  by 
the  inferior  profunda  artery.  At  the  elbow  it  is  superficial,  and 
supported  by  the  inner  condyle,  against  which  it  is  easily  com- 
pressed, giving  rise  to  the  thrilling  sensation  along  the  inner  side  of 
the  fore-arm  and  little  finger,  ascribed  to  striking  the  "  funny  bone." 
It  then  passes  between  the  two  heads  of  the  flexor  carpi  ulnaris  and 
descends  along  the  inner  side  of  the  fore-arm,  crosses  the  annular 
ligament,  and  divides  into  two  branches,  superficial  and  deep 
palmar.  At  the  commencement  of  the  middle  third  of  the  fore-arm, 
it  becomes  applied  against  the  artery,  and  lies  to  its  ulnar  side,  as 
far  as  the  hand. 

The  Branches  of  the  ulnar  nerve  are, — 

Muscular  in  the  upper  arm,  Dorsal  branch. 

Articular,  Superficial  palmar, 

Muscular  in  the  fore-arm.  Deep  palmar. 
Anastomotic, 

The  Muscular  branches  in  the  upper  arm  arc  a  few  filaments  dis. 
tributed  to  the  triceps. 

The  Articular  branches  are  several  filaments  to  the  elbow-joint. 


412  3IUSCULO-SPIRAL  NERVE. 

which  are  given  off  from  the  nerve  as  it  lies  in  the  groove  betw^een 
the  inner  condyle  and  the  olecranon. 

The  Muscular  branches  in  the  fore-arm  are  distributed  to  the 
flexor  carpi  ulnaris  and  flexor  profundus  digitorum  muscle. 

The  jlnastomotic  branch  is  a  small  nerve  which  arises  from  the 
ulnar  at  about  the  middle  of  the  fore-arm,  and  divides  into  a  deep 
and  a  superficial  branch  ;  the  former  accompanies  the  ulnar  artery, 
and  the  latter  pierces  the  deep  fascia  and  communicates  with  the 
internal  cutaneous  nerve. 

The  Dorsal  branch  passes  beneath  the  tendon  of  the  flexor  carpi 
ulnaris,  at  the  lower  third  of  the  fore-arm,  and  divides  into  branches 
w^hich  supply  the  integument  and  two  fingers  and  a  half  on  the  pos- 
terior aspect  of  the  hand,  and  communicate  with  the  radial  nerve. 

The  Superficial  palmar  branch  divides  into  three  filaments,  which 
are  distributed, — one  to  the  ulnar  side  of  the  little  finger,  one  to  the 
adjoining  borders  of  the  httle  and  ring  fingers,  and  a  communica- 
ting branch  to  join  the  median  nerve. 

The  Deep  'palmar  branch  passes  between  the  abductor  and  flexor 
minimi  digiti,  to  the  deep  palmar  arch,  supplying  the  muscles  of  the 
little  finger,  and  the  lumbricales  and  interossei  in  the  palm  of  the 
hand. 

The  MuscuLO-spiRAii  Nerve,  the  largest  branch  of  the  brachial 
plexus,  arises  from  the  posterior  part  of  the  plexus  by  a  common 
trunk  with  the  circumflex  nerve.  It  passes  downwards  from  its 
origin  in  front  of  the  tendons  of  the  latissimus  dor  si  and  teres  major 
muscle,  and  winds  around  the  humerus  in  the  spiral  groove,  accom- 
panied by  the  superior  profunda  artery,  to  the  space  between  the 
brachialis  anticus  and  supinator  longus  muscle,  and  thence  onwards 
to  the  bend  of  the  elbow,  where  it  divides  into  two  branches,  the 
posterior  interosseous  and  radial  nerve. 

The  Branches  of  the  musculo-spiral  nerve  are, — 

Muscular, 

Spiral  cutaneous. 

Radial, 

Posterior  interosseous. 

The  Muscular  branches  are  distributed  to  the  triceps,  to  the  su- 
pinator longus,  and  to  the  extensor  carpi  radialis  longior. 

The  Spiral  cutaneous  nerve  pierces  the  deep  fascia  immediately 
below  the  insertion  of  the  deltoid  muscle,  and  passes  down  the  outer 
side  of  the  fore-arm  as  far  as  the  wrist.  It  is  distributed  to  the 
integument. 

The  Radial  nerve  runs  along  the  radial  side  of  the  fore-arm  to 
the  commencement  of  its  lower  third  ;  it  then  passes  beneath  the 
tendon  of  the  supinator  longus,  and  at  about  two  inches  above  the 
wrist-joint  divides  into  an  external  and  an  internal  branch.  The 
external  branch,  the  smaller  of  the  two,  is  distributed  to  the  outer 
border  of  the  hand  and  of  the  thumb.     The  internal  branch  crosses 


CIRCUMFLEX  NERVE DORSAL  NERVES.  413 

the  direction  of  the  extensor  tendons  of  the  thumb  and  divides  into 
several  filaments  for  the  supply  of  the  ulnar  border  of  the  thumb, 
the  radial  border  of  the  index  finger,  and  the  adjoining  borders  of 
the  index  and  middle  fingers.  It  communicates  on  the  back  of  the 
hand  with  the  dorsal  branch  of  the  ulnar  nerve. 

In  the  upper  third  of  the  fore-arm  the  radial  nerve  lies  beneath 
the  border  of  the  supinator  longus  muscle.  In  the  middle  third  it 
is  in  relation  with  the  radial  artery  lying  to  its  outer  side.  It  then 
quits  the  artery,  and  passes  beneath  the  tendon  of  the  supinator 
longus,  to  reach  the  back  of  the  hand. 

The  Posterior  interosseous  nerve  separates  from  the  radial  at  the 
bend  of  the  elbow,  pierces  the  supinator  brevis  muscle,  and  emerges 
from  its  lower  border  on  the  posterior  aspect  of  the  fore-arm,  where 
it  divides  into  branches  which  supply  the  whole  of  the  muscles  on 
the  posterior  aspect  of  the  fore-arm.  One  branch,  longer  than  the 
rest,  descends  to  the  posterior  part  of  the  wrist,  and  forms  a  large 
gangliform  swelling  (the  common  character  of  nerves  which  supply 
joints),  from  which  numerous  branches  are  distributed  to  the  wrist- 
joint. 

The  Circumflex  Nerve  arises  from  the  posterior  part  of  the 
brachial  plexus  by  a  common  trunk  with  the  musculo-spiral  nerve. 
It  passes  downwards  over  the  border  of  the  subscapularis  muscle, 
winds  around  the  neck  of  the  humerus,  with  the  posterior  circumflex 
artery,  and  terminates  by  dividing  into  numerous  branches  which 
supply  the  deltoid  muscle. 

The  Branches  of  the  circumflex  nerve  are  muscular  and  cuta- 
neous. The  Muscular  branches  are  distributed  to  the  subscapularis, 
teres  minor,  teres  major,  latissimus  dorsi,  and  deltoid.  The  cuta- 
neous branches  pierce  the  deltoid  muscle  and  are  distributed  to  the 
integument  of  the  shoulder.  One  of  these  cutaneous  branches, 
larger  than  the  rest,  winds  around  the  posterior  border  of  the  del- 
toid, and  divides  into  filaments  which  pass  in  a  radiating  direction 
across  the  shoulder  and  are  distributed  to  the  integument. 

DORSAL  NERVES. 

The  dorsal  nerves  are  twelve  in  number  on  each  side ;  the  first 
appears  between  the  first  and  second  dorsal  vertebra,  and  the  last 
between  the  twelfth  dorsal  and  first  lumbar.  Each  nerve,  as  soon 
as  it  has  escaped  from  the  intervertebral  foramen,  divides  into  two 
branches  ;  a  dorsal  branch  and  the  true  intercostal  nerve. 

The  Dorsal  branches  pass  directly  backwards  between  the  trans- 
verse processes  of  the  vertebrae,  lying  internally  to  the  anterior 
costo-transverse  ligament,  where  each  nerve  divides  into  a  muscular 
and  a  musculo-cutaneous  branch.  The  muscular  branch  enters  the 
substance  of  the  muscles  in  the  direction  of  a  line  corresponding 
with  the  interval  of  separation  between  the  longissimus  dorsi  and 
sacro-lumbalis,  and  is  distributed  to  the  muscles  of  the  back.  The 
musculo-cutaneous  branch  passes  inwards,  crossing  the  semispinalis 


414  INTERCOSTAL  NERVES. 

dorsi  to  the  spinous  processes  of  the  dorsal  vertebrae ;  it  then  pierces 
the  aponeurosis  of  origin  of  the  trapezius  and  latissimus  dorsi,  and 
divides  into  branches  which  are  inclined  outwards  beneath  the  in- 
tegument to  which  they  are  distributed.  The  posterior  branch  of 
the  first  dorsal  nerve  resembles  in  its  mode  of  distribution  the  pos- 
terior branches  of  the  last  cervical.  The  posterior  branches  of  the 
four  last  dorsal  nerves  pass  obliquely  downwards  and  outwards  into 
the  substance  of  the  erector  spinas  in  the  situation  of  the  interspace 
between  the  sacro-lumbalis  and  longissimus  dorsi.  After  supplying 
the  erector  spinse  and  communicating  freely  with  each  other  they 
approach  the  surface  along  the  outer  border  of  the  sacro-lumbalis, 
where  they  pierce  the  aponeuroses  of  the  transversalis,  internal 
oblique,  serratus  posticus  inferior,  and  latissimus  dorsi  muscle,  and 
divide  into  internal  branches  which  supply  the  integument  upon  the 
middle  line  in  the  lumbar  region,  and  external  branches  which  are 
distributed  to  the  integument  upon  the  side  of  the  lumbar  and  in  the 
gluteal  region. 

The  Intercostal  nerves  receive  one  or  two  filaments  from  the  ad- 
joining ganglia  of  the  sympathetic,  and  pass  forwards  in  the  inter- 
costal space  with  the  intercostal  vessels,  lying  below  the  veins  and 
artery.  At  the  termination  of  the  intercostal  spaces  near  to  the 
sternum,  the  nerves  pierce  the  intercostal  and  pectoral  muscles,  and 
incline  downwards  and  outwards  to  be  distributed  to  the  integu- 
ment of  the  mamma  and  front  of  the  chest.  Those  which  are  situ- 
ated between  the  false  ribs  pass  behind  the  costal  cartilages,  and 
between  the  transversalis  and  obliquus  internus  muscles ;  and  sup- 
ply the  rectus  and  the  integument  on  the  front  of  the  abdomen. 
The  first  and  last  dorsal  nerves  are  exceptions  to  this  distribution. 
The  anterior  branch  of  the  first  dorsal  nerve  divides  into  two 
branches ;  a  smaller,  which  takes  its  course  along  the  under  surface 
of  the  first  rib  to  the  sternal  extremity  of  the  first  intercostal  space ; 
and  a  larger,  which  crosses  obliquely  the  neck  of  the  first  rib,  to 
join  the  brachial  plexus.  The  last  dorsal  nerve,  next  in  size  to  the 
first,  sends  a  branch  of  communication  to  the  first  lumbar  nerve,  to 
assist  in  forming  the  lumbar  plexus. 

The  Branches  of  each  intercostal  nerve  are  a  muscular  twig  to 
the  intercostal  and  neighbouring  muscles,  and  a  cutaneous  branch 
which  is  given  off  at  about  the  middle  of  the  arch  of  the  rib.  The 
first  dorsal  nerve  has  no  cutaneous  branch.  The  cutaneous  branches 
of  the  second  and  third  intercostal  nerves  are  named,  from  their 
origin  and  distribution,  intercosto-humeral. 

The  First  intercosto-humeral  nerve  is  of  large  size ;  it  pierces  the 
external  intercostal  muscle  of  the  second  intercostal  space,  and 
divides  into  an  internal  and  an  external  branch.  The  internal 
branch  is  distributed  to  the  integument  of  the  inner  side  of  the  arm. 
The  external  branch  communicates  with  the  nerve  of  Wrisberg, 
and  divides  into  filaments  which  supply  the  integument  upon  the 
inner  and  posterior  aspect  of  the  arm  as  far  as  fhe  elbow.  This 
nerve  sometimes  takes  the  place  of  the  nerve  of  Wrisberg. 


LUMBAR  NERVES.  415 

The  Second  intercosto-humeral  nerve  is  much  smaller  than  the 
preceding ;  it  emerges  from  the  external  intercostal  muscle  of  the 
third  intercostal  space  between  the  serrations  of  the  serratus  magnus 
muscle,  and  divides  into  filaments  which  are  distributed  to  the  inte- 
gument of  the  shoulder.  One  of  these  filaments  may  be  traced  in- 
wards to  the  integument  of  the  mamma. 

The  cutaneous  branches  of  the  fourtli  and  fifth  intercostal  nerve 
send  twigs  to  the  integument  of  the  mammary  gland.  The  cuta- 
neous branches  of  the  remaining  intercostal  nerves  reach  the  surface 
between  the  serrations  of  the  serratus  magnus  muscle  above  and 
the  external  oblique  below,  and  each  nerve  divides  into  an  anterior 
and  a  fosterior  branch ;  the  former  being  distributed  to  the  integu- 
ment of  the  antero-lateral,  and  the  latter  to  that  of  the  lateral  part 
of  the  trunk. 

The  cutaneous  branch  of  the  last  dorsal  nerve  is  remarkably  large ; 
it  pierces  the  internal  and  external  oblique  muscles,  crosses  the  crest 
of  the  ilium,  and  is  distributed  to  the  integument  of  the  gluteal 
region. 

LUMBAR  NERVES. 

There  are  five  pairs  of  lumbar  nerves,  of  which  the  first  makes 
its  appearance  between  the  first  and  second  lumbar  vertebra,  and 
the  last  between  the  fifth  lumbar  and  the  base  of  the  sacrum.  The 
anterior  branches  increase  in  size  from  above  downwards,  and  form 
the  lumbar  plexus.  The  posterior  branches  diminish  in  size  from 
above  downwards ;  they  form  loops  of  communication  with  each 
other,  and  are  distributed  to  the  muscles  of  the  lumbar  region,  and 
to  the  integument  over  the  sacrum  in  the  same  manner  with  the 
posterior  branches  of  the  lower  dorsal  nerves. 

The  lumbar  -plexus  is  formed  by  the  communications  and  anasto- 
moses which  take  place  between  the  anterior  branch  of  the  last 
dorsal  and  of  the  five  lumbar  nerves.  It  is  narrow  above  and  in- 
creases in  breadth  inferiorly,  is  situated  between  the  transverse 
processes  of  the  lumbar  vertebrse  and  the  psoas  magnus  muscle, 
and  receives  filaments  of  communication  from  the  lumbar  ganglia 
of  the  sympathetic. 

The  Branches  of  the  lumbar  plexus  are  the 

Musculo-cutaneous, 

External-cutaneous, 

Genito-crural, 

Crural, 

Obturator, 

Lumbo-sacral. 

The  Musculo-cutaneous  nerves,  two  in  number,  superior  and  infe- 
rior, proceed  from  the  first  lumbar  nerve.  The  superior  musculo- 
cutaneous nerve  (ilio-scrotal)  passes  outwards  between  the  posterior 
fibres  of  the  psoas  magnus,  and  crosses  obliquely  the  quadratus  lum- 


416 


BRANCHES  OF  THE  LUMBAR  PLEXUS. 


133.*  borum  muscle  to  the  crest  of  the  iUiim.     It 

then  pierces  the  transversalis  muscle,  winds 
along  the  crest  of  the  ilium  between  the  trans- 
.  versalis  and  internal  oblique,  and  divides  into 
'  two  branches,  abdominal  and  scrotal.     The 
abdominal  branch  is  continued  forwards  par- 
allel with  the  last  intercostal  muscle  to  the 
rectus  muscle,  to  which  it  is  distributed,  send- 
L  ing  a  branch  forwards  to  the  integument  of 
the   abdomen.     The  scrotal  branch   opposite 
the  anterior  superior  spinous  process  of  the 
ilium,  communicates  with  the  inferior  mus- 
culo-cutaneous  nerve,  and  escapes  at  the  ex- 
ternal  abdominal   ring,  with   the   spermatic 
cord  in  the  male,  and  with  the  round  liga- 
ment in  the  female.     It  is  distributed  to  the 
integument  of  the  front  of  the  os  pubis  and  of 
fairn  I    II  the  groin,  to  the  scrotum  in  the  male  and  to 

the  greater  labium  in  the  female.  The  infe- 
rior musculo-cutaneous  nerve  also  arises  from 
the  first  lumbar  nerve.  It  is  much  smaller 
than  the  preceding,  crosses  the  quadratus 
lumborum  below  it,  and  takes  the  same  course 
along  the  crest  of  the  ilium.  It  terminates, 
either  by  communicating  with  the  superior 
nerve,  or  by  escaping  with  it  through  the  ex- 
ternal abdominal  ring  and  following  the  same 
distribution. 

The  External  cutaneous  nerve  (inguino-cu- 
taneous)  proceeds  from  the  second  lumbar 
nerve.  It  pierces  the  posterior  fibres  of  the 
psoas  muscle ;  and  crossing  the  ihacus  ob- 
liquely, lying  beneath  the  iliac  fascia  to  the 
anterior  superior  spinous  process  of  the  ihum, 
passes  into  the  thigh  beneath  Poupart's  liga- 
ment. It  then  pierces  the  fascia  lata  at  about 
two  inches  below  the  anterior  superior  spine 

*  A  diagram  showin;^  the  lumbar  and  sacral  plexuses,  with  the  nerves  of  the  lower 
extremity.  ] .  The  five  lumbar  nerves ;  whieh,  with  a  branch  from  the  last  dorsal, 
constitute  the  lumbar  plexus.  2.  The  four  upper  sacral  nerves ;  wliich,  with  the  last 
lumbar,  form  the  sacral  plexus.  3.  The  two  musculo-cutaneous  nerves,  branches  of  the 
first  lumbar  nerve.  4.  The  external-cutaneous  nerve.  5.  The  gcnilo-crural  nerve.  6. 
The  crural  or  femoral  nerve.  7.  Its  muscular  branches.  8.  Its  cutaneous  branches, 
middle  cutaneous.  9.  Its  descending  or  saphenous  branches.  10.  The  short  saphenous 
nerve.  11.  The  long  or  internal  saphenous.  12.  The  obturator  nerve.  13.  The  gluteal 
nerve;  a  branch  of  the  lumbo-sacral  nerve.  14.  The  interntil  pudic  nerve.  15.  The 
lesser  ischiatic  nerve.  10.  The  greater  ischiatic  nerve.  17.  The  popliteal  nerve.  18. 
The  peroneal  nerve.  1!).  The  muscuhir  Ijranchcs  of  the  ])0|)]jtc!al.  20.  Tlie  posterior 
tibial  nerve  ;  dividing  at  21,  into  the  two  plantar  nerves.  22.  The  external  saphenous 
nerve,  formed  by  the  union  of  tlic  communieans  poplitci  and  connnunicans  pcronei. 
23.  The  anterior  tibial  nerve.  24.  The  musculo-cutaneous  nerve,  piercing  the  dcci» 
fascia,  and  dividing  into  two  cutaneous  branches,  for  the  supply  of  the  dorsum  of  the 
foot. 


CRURAL  NERVE BRANCHES.  417 

of  the  ilium,  and  divides  into  two  branches,  anterior  and  posterior. 
The  'posterior  branch  crosses  the  tensor  vaginae  femoris  muscle  to 
the  outer  and  posterior  side  of  the  thigh,  and  supplies  the  integu- 
ment in  that  region.  The  anterior  nerve  divides  into  tv^^o  branches 
which  are  distributed  to  the  integument  upon  the  outer  border  of 
the  thigh,  and  to  the  articulation  of  the  knee. 

The  Genito-crural  proceeds  also  from  the  second  lumbar  nerve. 
It  traverses  the  psoas  magnus  from  behind  forwards,  and  runs 
down  on  the  anterior  surface  of  that  muscle  and  beneath  its  fascia 
to  near  Poupart's  ligament,  where  it  divides  into  a  genital  and  a 
crural  branch.  The  genital  branch  crosses  the  external  iliac  artery 
to  the  internal  abdominal  ring  and  descends  along  the  spermatic 
canal,  lying  behind  the  cord  to  the  scrotum,  where  it  divides  into 
branches  which  supply  the  spermatic  cord  and  cremaster  in  the  male, 
and  the  round  ligament  in  the  female.  At  the  internal  abdominal 
ring  this  nerve  sends  some  filaments  to  the  lower  border  of  the  inter- 
nal oblique  and  transversalis  muscle.  The  crural  branch  enters  the 
sheath  of  the  femoral  vessels  in  front  of  the  femoral  artery.  It 
pierces  the  sheath  below  Poupart's  ligament,  and  is  distributed  to 
the  integument  of  the  anterior  aspect  of  the  thigh  as  far  as  its  middle. 
This  nerve  often  communicates  with  a  cutaneous  branch  of  the 
crural  nerve  in  the  thigh. 

The  Crural,  or  Femoral  Nerve,  is  the  largest  of  the  divisions 
of  the  lumbar  plexus ;  it  is  formed  by  the  union  of  the  branches  from 
the  second,  third,  and  fourth  lumbar  nerves,  and,  emerging  from 
beneath  the  psoas  muscle,  passes  downwards  in  the  groove  between 
it  and  the  iliacus,  and  beneath  Poupart's  ligament  into  the  thigh, 
where  it  spreads  out  and  divides  into  numerous  branches.  At  Pou- 
part's ligament  it  is  separated  from  the  femoral  artery  by  the  breadth 
of  the  psoas  muscle,  which  at  this  point  is  scarcely  more  than  half 
an  inch  in  diameter,  and  by  the  iliac  fascia,  beneath  which  it  lies. 

Branches. — While  situated  within  the  pelvis  the  crural  nerve 
gives  off  several  muscular  branches  to  the  iliacus  and  psoas.  On 
emerging  from  beneath  Poupart's  ligament  the  nerve  becomes  flat- 
tened and  divides  into  numerous  branches,  which  may  be  arranged 
into, — 

Cutaneous, 

Muscular, 

Branch  to  the  femoral  sheath, 

Short  saphenous  nerve, 

Long  saphenous  nerve. 

The  Cutaneous  branches  are  four  or  five  in  number ;  they  pierce 
the  fascia  lata  at  irregular  distances  below  Poupart's  ligament,  and 
are  distributed  to  the  integument  on  the  front  and  inner  side  of  the 
thigh,  constituting  the  middle  and  internal  cutaneous  nerves.  Two 
of  these  nerves  pass  through  the  sartorius  muscle  before  becoming 
cutaneous. 

53 


418  SAPHE^"OUS  NERVE, 

The  Muscular  branches  are  several  large  twigs  which  are  distri- 
buted to  the  muscles  on  the  anterior  aspect  of  the  thigh.  Two  or 
three  of  these  branches  are  sent  to  the  sartorius ;  one  to  the  tensor 
vaginse  femoris,  one  to  the  rectus,  one  to  the  vastus  externus,  and 
one  of  very  large  size  to  the  vastus  internus  and  crurseus.  The 
latter  sends  off  a  cutaneous  branch  and  several  filaments  to  the 
periosteum  of  the  lower  part  of  the  femur,  and  to  the  articulation  of 
the  knee. 

The  Branch  to  the  femoral  sheath  is  a  small  nerve  which  passes 
inwards  to  the  sheath  of  the  femoral  vessels  at  the  upper  part  of  the 
thigh,  and  divides  into  several  filaments  which  surround  the  femoral 
and  profunda  vessels.  Two  of  these  filaments,  one  from  the  front, 
and  the  other  from  the  posterior  part  of  the  sheath,  unite  to  form  a 
small  nerve  which  escapes  from  the  saphenous  opening  and  passes 
downwards  with  the  saphenous  vein.  Other  filaments  are  distributed 
to  the  adductor  muscles,  and  communicate  with  the  internal  saphe- 
nous nerve. 

The  Short  saphenous  nerve  inclines  inwards  to  the  sheath  of  the 
femoral  vessels,  and  divides  into  a  superficial  and  a  deep  branch. 
The  superficial  branch  passes  downwards  along  the  inner  border  of 
the  sartorius  muscle  to  the  lower  third  of  the  thigh,  it  then  joins  the 
internal  saphenous  vein  and  accompanies  that  vessel  to  the  knee- 
joint,  when  it  terminates  by  communicating  with  the  long  saphenous 
nerve.  The  deep  branch  descends  upon  the  outer  side  of  the  sheath 
of  the  femoral  vessels,  and  crosses  the  sheath  at  its  lower  part  to  a 
point  opposite  to  the  termination  of  the  femoral  artery,  where  it 
divides  into  several  filaments  which  constitute  a  plexus  by  their 
communication  with  other  nerves.  One  of  these  filaments  commu- 
nicates with  the  descending  branch  of  the  obturator  nerve,  another 
with  the  long  saphenous  nerve,  and  two  or  three  are  distributed  to 
the  integument  upon  the  internal  and  posterior  aspect  of  the  thigh. 

The  Long  saphenous  nerve  inclines  inw^ards  to  the  sheath  of  the 
femoral  vessels,  and  entering  the  sheath  accompanies  the  femoral 
artery  to  the  tendinous  canal  formed  by  the  adductor  longus  and 
vastus  internus  muscles.  It  then  quits  the  artery,  and,  passing  be- 
tween the  tendons  of  the  sartorius  and  gracilis,  descends  along  the 
inner  side  of  the  leg  with  the  internal  saphenous  vein,  crosses  in 
front  of  the  inner  ankle,  and  is  distributed  to  the  integument  on  the 
inner  side  of  the  foot  as  far  as  the  great  toe. 

The  internal  saphenous  nerve  receives  at  its  upper  part  a  large 
branch  of  communication  from  the  obturator  nerve,  and  another  at 
the  inner  side  of  the  knee-joint.  In  its  course  it  gives  off"  an  articu- 
lar branch  for  the  supply  of  the  synovial  membrane  of  the  knee- 
joint,  and  several  cutaneous  nerves ;  one  to  the  integument  of  the 
thigh ;  one,  of  large  size,  which  pierces  the  lower  part  of  the  sartorius 
and  distributes  filaments  to  the  integument  of  the  knee,  and  some  to 
the  intogiirnent  of  the  leg,  of  the  inner  ankle,  and  of  the  inner  side 
of  the  loot. 

The  Obturator  nerve  is  formed  by  a  branch  from  the  third,  and 


SACRAL  NERVES.  419 

another  from  the  fourth  lumbar  nerve.  It  passes  downwards  in  the 
fibres  of  the  psoas  muscle  through  the  angle  of  bifurcation  of  the 
common  ihac  vessels,  and  along  the  inner  border  of  the  brim  of  the 
pelvis,  to  the  obturator  foramen,  where  it  joins  the  obturator  artery. 
Having  escaped  from  the  pelvis  it  gives  oft'  two  small  branches  to 
the  obturator  externus  muscle  and  divides  into  four  branches, — 
three  anterior,  which  pass  in  front  of  the  adductor  brevis,  supplying 
that  muscle,  the  pectineus,  the  adductor  longus,  and  the  gracilis ; 
and  a  posterior  branch  which  passes  downwards  behind  the  adductor 
brevis,  and  ramifies  in  the  adductor  magnus. 

From  the  branch  which  supplies  the  adductor  brevis,  a  communi- 
cating filament  passes  outwards  through  the  angle  of  bifurcation  of 
the  femoral  vessels  to  unite  with  the  long  saphenous  nerve.  From 
the  branch  to  the  adductor  longus  a  long  cutaneous  nerve  proceeds, 
which  issues  from  beneath  the  inferior  border  of  that  muscle,  sends 
filaments  of  communication  to  the  plexus  of  the  short  saphenous 
nerve,  and  descends  to  the  inner  side  of  the  knee,  where  it  pierces 
the  fascia  and  communicates  with  the  long  saphenous  nerve.  It  is 
distributed  to  the  integument  upon  the  inner  side  of  the  leg.  From 
the  posterior  branch  an  articular  branch  is  given  off  which  pierces 
the  adductor  magnus  muscle,  accompanies  the  pophteal  artery,  and 
is  distributed  to  the  synovial  membrane  of  the  knee-joint  on  its  pos- 
terior aspect. 

The  Lumbosacral  nerve. — The  anterior  division  of  the  fifth  lum- 
bar nerve,  conjoined  with  a  branch  from  the  fourth,  constitutes  the 
lumbo-sacral  nerve  which  descends  over  the  base  of  the  sacrum  into 
the  pelvis,  and  assists  in  forming  the  sacral  plexus. 

SACRAL  NERVES. 

There  are  six  pairs  of  sacral  nerves  ;  the  first  escapes  from  the 
vertebral  canal  through  the  first  sacral  foramina,  and  the  two  last 
between  the  sacrum  and  coccyx.  The  •  posterior  sacral  nerves 
are  very  small  and  diminish  in  size  from  above  downwards ;  they 
communicate  with  each  other  immediately  after  their  escape  from 
the  posterior  sacral  foramina,  and  divide  into  branches  which  are 
distributed  to  the  muscles  and  integument  in  the  sacral  and  gluteal 
region.  The  anterior  sacral  nerves  diminish  in  size  from  above 
downwards ;  the  first  is  of  large  size  and  unites  with  the  lumbo- 
sacral nerve ;  the  second,  of  equal  size,  unites  with  the  preceding ; 
the  third,  which  is  scarcely  one-fourth  the  size  of  the  third,  also 
joins  with  the  preceding  nerves  in  the  formation  of  the  sacral  plexus ; 
the  fourth  is  atjout  one-third  the  size  of  the  preceding  sacral  nerve, 
it  divides  into  several  branches,  one  of  which  is  sent  to  the  sacral 
plexus,  a  second  to  join  the  fifth  sacral  nerve,  a  third  to  the  viscera 
of  the  pelvis,  communicating  with  the  hypogastric  plexus,  and  a 
fourth  to  the  coccygeus  muscle,  and  to  the  integument  around  the 
anus.  The  fifih  anterior  sacral  nerve  presents  about  half  the  size  of 
the  fourth  ;  it  divides  into  two  branches,  one  of  which  communicates 


420  SACRAL  PLEXUS. 

with  the  Toiirth,  the  other  M'ith  the  sixth.  The  sixth  sacral  nerve  is 
exceedingly  small ;  it  gives  off  an  ascending  filament  which  is  con- 
tinuous with  the  communicating  branch  of  the  fifth ;  and  a  descend- 
ino-  filament  which  passes  downwards  by  the  side  of  the  coccyx 
and  traverses  the  fibres  of  the  great  sacro-ischiatic  ligament  to  be 
distributed  to  the  gluteus  maximus  and  to  the  integument.  All  the 
anterior  sacral  nerves  receive  branches  from  the  sacral  ganglia  of 
the  sympathetic  at  their  emergence  from  the  sacral  foramina. 

The  Sacral  plexus  is  formed  by  the  lumbo-sacral,  and  by  the 
anterior  branches  of  the  four  upper  sacral  nerves.  The  plexus  is 
triangular  in  form,  the  base  corresponding  with  the  whole  length  of 
the  sacrum,  and  the  apex  with  the  lower  part  of  the  great  ischiatic 
foramen.  It  is  in  relation  behind  with  the  pyriformis  muscle,  and 
in  front  with  the  pelvic  fascia  which  separates  it  from  the  branches 
of  the  internal  iliac  artery,  and  from  the  viscera  of  the  pelvis. 

The  Branches  of  the  sacral  plexus  are  divisible  into  the  internal 
and  the  external ;  they  may  be  thus  arranged  : 

Internal.  External. 

Visceral,  Muscular, 

Muscular.  Gluteal, 

Internal  pudic, 
Lesser  ischiatic, 
Greater  ischiatic. 

The  Visceral  nerves  are  three  or  four  large  branches  which  are 
derived  from  the  fourth  and  fifth  sacral  nerves :  they  ascend  upon 
the  side  of  the  rectum  and  bladder ;  in  the  female  upon  the  side  of 
the  rectum,  the  vagina  and  the  bladder ;  and  interlace  with  the 
branches  of  the  hypogastric  plexus,  sending  in  their  course  numerous 
filaments  to  those  viscera. 

The  Muscular  branches  given  off  within  the  pelvis  are  one  or  two 
twigs  to  the  levator  ani ;  an  obturator  branch  which  curves  around 
the  spine  of  the  ischium  to  reach  the  internal  surface  of  the  obturator 
internus  muscle  ;  and  an  hoemorrhoidal  nerve  which  descends  to 
the  termination  of  the  rectum  to  supply  the  sphincter  and  the  in- 
tegument. 

The  Muscular  branches  supplied  by  the  sacral  plexus  externally 
to  the  pelvis  are,  a  branch  to  the  pyramidalis ;  a  branch  to  the 
gemellus  superior  ;  and  a  branch  of  moderate  size  which  descends 
between  the  gemelli  muscles  and  the  ischium,  and  is  distributed  to 
the  gemellus  inferior,  the  quadratus  fcmoris,  and  to  the  capsule  of 
the  hip-joint. 

The  Gluteal  nerve  is  a  branch  of  the  lumbo-sacral ;  it  passes  out 
of  the  pelvis  with  the  gluteal  artery,  through  the  great  sacro-ischiatic 
foramen,  and  divides  into  a  superior  and  an  inferior  brancii.  The 
superior  branch  follows  the  direction  of  the  su[)erior  curved  line  of 
the  ilium,  accompanying  the  deep  superior  branch  of  the  gluteal 
artery,  and  sending  filaments  to  the  gluteus  medius  and  minimus. 


LESSER  ISCHIATIC  NERVE.  421 

The  inferior  passes  obliquely  downwards  and  forwards  between  the 
gluteus  medius  and  minimus,  distributing  numerous  filaments  to  both, 
and  terminates  in  the  tensor  vaginae  femoris  muscle. 

The  Internal  pudic  nerve  arises  from  the  lower  part  of  the  sacral 
plexus,  passes  out  of  the  pelvis  through  the  great  sacro-ischiatic 
foramen  below  the  pyriformis  muscle,  and  takes  the  course  of  the 
internal  pudic  artery.  While  situated  beneath  the  obturator  fascia 
it  lies  below  that  vessel  and  divides  into  a  superior  and  an  inferior 
branch.  The  superior  nerve  ascends  upon  the  posterior  surface  of 
the  ramus  of  the  ischium,  pierces  the  deep  perineal  fascia  and  ac- 
companies the  arteria  dorsalis  penis  to  the  glans  to  which  it  is  dis- 
tributed. At  the  root  of  the  penis  this  nerve  gives  off  a  cutaneous 
branch  which  runs  along  the  side  of  the  organ,  and  with  its  fellow 
of  the  opposite  side  supplies  the  integument  of  the  upper  two-thirds 
of  the  penis  and  of -the  prepuce.  The  inferior  or  perineal  nerve 
pursues  the  course  of  the  internal  pudic  artery  in  the  perineum  and 
sends  off  three  principal  branches, — 1,  an  external  perineal  nerve 
which  ascends  upon  the  outer  side  of  the  crus  penis,  and  supplies 
the  scrotum ;  2,  a  superficial  perineal  nerve  which  accompanies  the 
artery  of  that  name  and  distributes  filaments  to  the  scrotum,  to  the 
integument  of  the  under  part  of  the  penis  and  to  the  prepuce ;  3, 
the  nerve  of  the  bulb,  which  sends  twigs  to  the  sphincter  ani,  to  the 
transversus  perinei,  and  accelerator  urinee,  and  terminates  by  ramify- 
ing in  the  corpus  spongiosum. 

In  the  female  the  internal  pudic  nerve  is  distributed  to  the  parts 
analogous  to  those  of  the  male.  The  superior  branch  supplies  the 
clitoris  ;  and  the  inferior  the  parts  in  the  perineum  and  the  vulva. 

The  Lesser  iscliiaiic  nerve  passes  out  of  the  pelvis  through  the 
great  sacro-ischiatic  foramen  below  the  pyriformis  muscle,  and 
divides  into  muscular  and  cutaneous  branches.  The  muscular 
branches — inferior  gluteal — are  distributed  to  the  gluteus  maximus ; 
some  ascending  in  the  substance  of  that  muscle  to  its  upper  border, 
and  others  descending.  The  cutaneous  branches  are  two  in  number, 
— the  perineal  cutaneous  and  the  middle  posterior  cutaneous.  The 
perineal  cutaneous  nerve  (pudendalis  longus  inferior  ;  Soem.)  curves 
around  the  tuberosity  of  the  ischium  and  ascends  in  a  direction 
parallel  to  the  ramus  of  the  ischium  and  os  pubis  to  the  scrotum, 
where  it  communicates  with  the  superficial  perineal  nerve,  and  di- 
vides into  an  internal  and  an  external  branch.  The  internal  branch 
passing  down  upon  the  inner  side  of  the  testis  to  the  scrotum  ;  the 
external  branch  to  its  outer  side,  and  both  terminating  in  the  integu- 
ment of  the  under  border  of  the  penis.  The  middle  posterior  cuta- 
neous nerve  crosses  the  tuberosity  of  the  ischium,  and  pierces  the 
deep  fascia  at  the  lower  border  of  the  gluteus  maximus.  It  then 
passes  downwards  along  the  middle  of  the  posterior  aspect  of  the 
thigh,  and  of  the  popliteal  region,  and  is  distributed  to  the  integument 
as  far  as  the  middle  of  the  calf  of  the  leg.  In  its  course  the  nerve 
gives  off  several  cutaneous  branches  to  the  integument  upon  the 
inner  and  outer  side  of  the  thigh,  and  in  the  popliteal  region  a  com- 


422  GREAT  ISCHIATIC  NERVE. 

municating  branch  wliich  pierces  the  fascia  of  the  leg  and  unites 
with  the  external  saphenous  nerve. 

The  Great  Ischiatic  Nerve  is  the  largest  nervous  cord  in  the 
body ;  it  is  formed  by  the  sacral  plexus,  or  rather  it  is  a  prolonga- 
tion of  the  plexus,  and  at  its  exit  from  the  great  sacro-ischiatic  fora- 
men beneath  the  pyriformis  muscle  measures  three  quarters  of  an 
inch  in  breadth.  It  descends  through  the  middle  of  the  space 
between  the  trochanter  major  and  tuberosity  of  the  ischium,  and 
along  the  posterior  part  of  the  thigh  to  about  its  lower  third,  where 
it  divides  into  two  large  terminal  branches,  popliteal  and  peroneal. 
This  division  sometimes  takes  place  at  the  plexus,  and  the  two 
nerves  descend  together  side  by  side ;  occasionally  they  are  sepa- 
rated at  their  commencement  by  a  part  or  the  whole  of  the  pyri- 
formis muscle.  The  nerve  in  its  course  down  the  thigh  rests  upon 
the  gemellus  superior,  tendon  of  the  obturator  internus,  gemellus 
inferior,  quadralus  femoris,  and  adductor  magnus  muscle,  and  is 
covered  in  by  the  gluteus  maximus,  and  by  the  biceps  and  semiten- 
dinosus  muscle. 

The  Branches  of  the  great  ischiatic  nerve,  previously  to  its  divi- 
sion, are  muscular  and  articular.  The  muscular  branches  are  given 
off  from  the  upper  part  of  the  nerve  and  supply  the  biceps,  the  semi- 
tendinosus,  the  semi-membranosus,  and  the  adductor  magnus.  The 
articular  branch  descends  to  the  upper  part  of  the  external  condyle 
of  the  femur,  and  divides  into  filaments  which  are  distributed  to  the 
fibrous  capsule  and  to  the  synovial  membrane  of  the  knee-joint. 

The  Popliteal  Nerve  passes  through  the  middle  of  the  popliteal 
space,  from  the  division  of  the  great  ischiatic  nerve  to  the  lower 
border  of  the  popliteus  muscle,  where  it  passes  with  the  artery 
beneath  the  arch  of  the  soleus,  and  becomes  the  posterior  tibial 
nerve.  It  is  superficial  in  the  whole  of  its  course,  and  lies  exter- 
nally to  the  vein  and  artery. 

The  Branches  of  the  popliteal  nerve  are  muscular  or  sural  and 
articular,  and  a  cutaneous  branch  the  communicans  poplitei. 

The  Muscular  branches,  of  considerable  size,  and  four  or  five  in 
number,  are  distributed  to  the  two  heads  of  the  gastrocnemius,  to 
the  soleus,  to  the  plantaris,  and  to  the  popliteus. 

The  Jirticular  nerve  pierces  the  ligamentum  posticum  Winslowi, 
and  supplies  the  interior  of  the  knee-joint.  It  usually  sends  a  twig 
to  the  popliteus  muscle. 

The  Communicans  poplitei  is  a  large  nerve  which  arises  from  the 
popliteal  at  about  the  middle  of  its  course,  and  descends  between 
the  two  heads  of  the  gastrocnemius,  and  along  the  groove  formed 
by  the  two  bellies  of  that  muscle ;  at  a  variable  distance  below  the 
articulation  of  the  knee  it  receives  a  large  branch,  the  communicans 
peronci,  from  the  peroneal  nerve,  and  the  two  together  constitute 
the  external  saphenous  nerve. 

The  External  saphenous  nerve  pierces  the  deep  fascia  below  the 
fleshy  part  of  the  gastrocnemius  muscle,  and  continues  its  course 
down  the  leg,  lying  along  the  outer  border  of  the  tendo  Achillis  and 


POSTERIOR  TIBIAL  NERVE.  423 

by  the  side  of  the  external  saphenous  vein  which  it  accompanies  to 
the  foot.  At  the  lower  part  of  the  leg  it  winds  around  the  outer 
malleolus,  and  is  distributed  to  the  outer  side  of  the  foot  and  of  the 
little  toe,  communicating  with  the  external  peroneal  cutaneous  nerve, 
and  sending  numerous  filaments  to  the  integument  of  the  heel  and  of 
the  sole  of  the  foot. 

The  Posterior  Tibial  Nerve  is"  continued  along  the  posterior 
aspect  of  the  leg  from  the  lower  border  of  the  popliteus  muscle  to 
the  posterior  part  of  the  inner  ankle,  where  it  divides  into  the 
internal  and  external  plantar  nerve.  In  the  upper  part  of  its  course 
it  lies  to  the  outer  side  of  the  posterior  tibial  artery;  it  then  becomes 
placed  superficially  to  that  vessel,  and  at  the  ankle  is  again  situated 
to  its  outer  side ;  in  the  lower  third  of  the  leg  it  lies  parallel  with  the 
inner  border  of  the  tendo  AchilUs. 

The  Branches  of  the  posterior  tibial  nerve  are  three  or  four  mus- 
cular twigs  to  the  deep  muscles  of  the  posterior  aspect  of  the  leg ; 
the  branch  to  the  flexor  longus  pollicis  accompanies  the  fibular 
arteiy ;  one  or  two  filaments  which  entwine  around  the  artery  and 
then  terminate  in  the  integument  :*  and  some  cutaneous  branches 
which  pass  downwards  upon  the  inner  side  of  the  os  calcis  and  are 
distributed  to  the  integument  of  the  heel. 

The  Internal  plantar  nerve,  larger  than  the  external,  crosses  the 
posterior  tibial  vessels  to  enter  the  sole  of  the  foot,  where  it  lies  in 
the  interspace  between  the  abductor  poUicis  and  flexor  brevis  digi- 
torum;  it  then  enters  the  sheath  of  the  latter  muscle,  and  divides 
opposite  the  bases  of  the  metatarsal  bones  into  three  digital  branches; 
one  to  supply  the  adjoining  sides  of  the  great  and  second  toe ;  the 
second  to  the  adjoining  sides  of  the  second  and  third  toe ;  and  the 
third  to  the  third  and  fourth  toes.  The  distribution  is  precisely 
similar  to  that  of  the  digital  branches  of  the  median  nerve. 

In  its  course  the  internal  plantar  nerve  gives  o^ cutaneous  branches 
to  the  integument  of  the  inner  side  and  sole  of  the  foot ;  musczdar 
branches  to  the  muscles  forming  the  inner  and  middle  group  of  the 
sole ;  a  digital  branch,  to  the  inner  border  of  the  great  toe ;  and 
articidar  branches  to  the  articulations  of  the  tarsal  and  metatarsal 
bones. 

The  External  plantar  nerve,  the  smaller  of  the  two,  follows  the 
course  of  the  external  plantar  artery  to  the  outer  border  of  the 
musculus  accessorius,  beneath  which  it  sends  several  large  mus- 
cular branches  to  supply  the  abductor  pollicis  and  the  articulations 
of  the  tarsal  and  metatarsal  bones.  It  then  gives  branches  to  the 
integument  of  the  outer  border  and  sole  of  the  foot,  and  sends  for- 
ward two  digital  branches  to  supply  the  little  toe  and  one  half  the 
next. 

*  It  is  extremely  interesting'  in  a  physiological  point  of  view,  to  observe  the  mode  of 
distribution  of  these  filaments.  I  have  traced  them  in  relation  with  several,  and  I  iiave 
no  doubt  tliat  they  exist  in  connexion  with  all  the  superficial  arteries.  Tliey  seem  to 
be  the  direct  monilors  to  the  artery  of  the  presence  or  approach  of  danger. 


424  PERONEAL  NERVE. 

The  Peroneal  Nerve  is  one  half  smaller  than  the  popliteal ;  it 
passes  downwards  by  the  side  of  the  tendon  of  the  biceps,  crossing 
the  inner  head  of  the  gastrocnemius  and  the  origin  of  the  soleus,  to 
the  neck  of  the  fibula,  where  it  pierces  the  origin  of  the  peroneus 
longus  muscle,  and  divides  into  two  branches,  the  anterior  tibial  and 
musculo-cutaneous. 

The  Branches  of  the  peroneal  nerve  previously  to  its  division  are, 
the  communicans  peronei,  cutaneous,  and  muscular.  The  comniu- 
nicans  peronei ,  much,  smaller  than  the  communicans  poplitei,  crosses 
the  external  head  of  the  gastrocnemius  to  the  middle  of  the  leg.  It 
there  sends  a  large  branch  to  join  the  communicans  poplitei  and 
constitute  the  external  saphenous  nerve,  and  descends  very  much 
reduced  in  size  by  the  side  of  the  external  saphenous  vein  to  the 
side  of  the  external  ankle,  to  which  and  to  the  integument  of  the 
heel  it  distributes  filaments.  The  cutaneous  branch  descends  in  the 
integument  upon  the  outer  side  of  the  leg,  in  which  it  ramifies. 
The  muscular  branches  proceed  from  near  the  termination  of  the 
peroneal  nerve  ;  they  are  distributed  to  the  upper  part  of  the  tibialis 
anticus. 

The  Anterior  tibial  nerve  commences  at  the  bifurcation  of  the 
peroneal,  upon  the  head  of  the  fibula,  and  passes  beneath  the  upper 
part  of  the  extensor  longus  digitorum,  to  reach  the  outer  side  of  the 
anterior  tibial  artery,  just  as  that  vessel  has  emerged  through  the 
opening  in  the  interosseous  membrane.  It  descends  the  anterior 
aspect  of  the  leg  with  the  artery;  lying  at  first  to  its  outer  side,  and 
then  in  front  of  it,  and  near  the  ankle  becomes  again  placed  to  its 
outer  side.  Reaching  the  ankle  it  passes  beneath  the  annular  liga- 
ment ;  it  accompanies  the  dorsalis  pedis  artery,  supplies  the  adjoin- 
ing sides  of  the  great  and  second  toes,  and  communicates  .with  the 
internal  peroneal  cutaneous  nerve. 

The  Branches  given  oflf  by  the  anterior  tibial  nerve  are,  muscular 
to  the  muscles  in  its  course,  and  on  the  foot  a  tarsal  branch  which 
passes  beneath  the  extensor  brevis  digitorum,  and  distributes  fila- 
ments to  the  interossei  muscles  and  to  the  articulations  of  the  tarsus 
and  metatarsus. 

The  Musculo-cutaneous  nerve  passes  downwards  in  the  direction 
of  the  fibula,  in  the  substance  of  the  peroneus  longus ;  it  then  passes 
forwards  to  get  between  the  peroneus  longus  and  brevis,  and  at  the 
lower  third  of  the  leg  pierces  the  deep  fascia,  and  divides  into  two 
peroneal  cutaneous  branches.  In  its  course  it  gives  off  several 
branches  to  the  peronei  muscles. 

The  Peroneal  cutaneous  nerves  pass  in  front  of  the  ankle-joint, 
and  are  distributed  to  the  integument  of  the  foot  and  of  the  toes ; 
the  external  supplying  three  toes  and  a  half,  and  the  internal  one 
and  a  half.  They  communicate  with  the  saphenous  and  anterior 
tibial  nerve.  The  external  saphenous  nerve  frequently  supplies  the 
fifth  toe  and  the  adjoining  side  of  the  fourth. 


CRANIAL  GANGLIA.  425 


SYMPATHETIC  SYSTEM. 


The  Sympathetic  system  consists  of  a  series  of  ganglia,  extending 
along  each  side  of  the  vertebral  column  from  the  head  to  the  coccyx, 
communicating  with  all  the  other  nerves  of  the  body,  and  distribu- 
ting branches  to  all  the  internal  organs  and  viscera. 

It  communicates  with  the  other  nerves  immediately  at  their  exit 
from  the  cranium  and  vertebral  canal.  The  fourth  and  sixth  nerves, 
however,  form  an  exception  to  this  rule ;  for  with  these  it  unites  in 
the  cavernous  sinus  ;  and  with  the  olfactory,  optic,  and  auditory,  at 
their  ultimate  expansions. 

The  branches  of  distribution  accompany  the  arteries  which  supply 
the  different  organs,  and  form  communications  around  them,  which 
are  called  plexuses,  and  take  the  name  of  the  artery  with  which 
they  are  associated :  thus  we  have  the  mesenteric  plexus,  hepatic, 
plexus,  splenic  plexus,  &c.  All  the  internal  organs  of  the  head, 
neck,  and  trunk  are  supplied  with  branches  from  the  sympathetic, 
and  some  of  them  exclusively ;  hence  it  is  considered  a  nerve  of 
organic  life. 

It  is  called  the  ganglionic  nerve  from  the  circumstance  of  beino^ 
formed  by  a  number  of  ganglia ;  and  from  the  constant  disposition 
which  it  evinces  in  its  distribution,  to  communicate  and  form  small 
knots  or  gangha. 

There  are  six  sympathetic  ganglia  in  the  head:  viz.,  the  ganglion 
of  Ribes ;  the  ciliary  or  lenticular  ;  the  naso-palatine,  or  Cloquet's ; 
the  spheno-palatine,  or  Meckel's  ;  the  submaxillary ;  and  the  otic,  or 
Arnold's :  three  in  the  neck  ;  superior,  middle,  and  inferior :  ticelve 
in  the  dorsal  region ;  four  in  the  lumbar  region  ;  and  four  or  five  in 
the  sacral  region. 

Each  ganglion  may  be  considered  as  a  distinct  centre  giving  off 
branches  in  four  different  directions,  viz.,  superior  or  ascending  to 
communicate  with  the  ganglion  above ;  inferior  or  descending,  to 
communicate  with  the  ganglion  below;  external  to  communicate 
with  the  spinal  nerves  ;  and  internal,  to  communicate  with  the  sym- 
pathetic filaments  of  the  opposite  side,  and  to  be  distributed  to  the 
viscera. 

CRANIAL  GANGLIA. 

Ganglion  of  Ribes, 

Ciliary,  or  lenticular  gangUon, 

Naso-palatine,  or  Cloquet's  gangHon, 

Spheno-palatine,  or  Meckel's  ganglion, 

Submaxillary  ganglion. 

Otic,  or  Arnold's  ganglion. 

1.  The  Ganglion  of  Ribes  is  a  smaU  ganghon  situated  upon  the 
anterior  communicating  artery,  and  formed  by  the  union  of  the 

54 


426 


CRANIAL  GANGLIA. 


sympathetic  filaments,  which  accompany  the  ramifications  of  the 
two  anterior  cerebral  arteries.  These  filaments  are  derived  from 
the  carotid  plexus  at  each  side  ;  and  through  their  intervention,  the 
ganghon  of  Ribes  is  brought  into  connexion  with  the  carotid 
plexus,  and  with  the  other  ganglia  of  the  sympathetic.  This  gan- 
ghon, though  of  very  spall  size,  is  interesting,  as  being  the  superior 
point  of  union  between  the  sympathetic  chains  of  opposite  sides  of 
the  body. 

Fig.  134.* 


2.  The  Ciliary  Ganglion  {lenticular)  is  a  small  quandrangular  and 
flattened  ganglion  situated  within  the  orbit,  between  the  optic  nerve 
and  the  external  rectus  muscle;  it  is  in  close  contact  with  the  optic 
nerve,  and  is  surrounded  by  a  quantity  of  fat,  which  renders  its  dis- 
section somewhat  difficult. 

Its  branches  of  distribution  are  the  ciliary,  which  arise  from  its 

*  The  cranial  gang-lia  of  the  sympathetic  nerve.  1.  The  ganglion  of  Ribes.  2,  The 
filament  by  which  it  communicates  with  the  carotid  plexus  (3).  4.  The  ciliary  or  len- 
ticular ganglion,  giving  off  ciliary  branches  for  the  supply  of  the  globe  of  the  eye. 
5.  Part  of  the  inferior  division  of  the  third  nerve,  receiving  a  short  thick  branch  from 
the  ganglion.  6.  Part  of  the  nasal  nerve,  receiving  a  longer  branch  from  the  ganglion. 
7.  A  slender  filament  sent  directly  backwards  from  the  ganglion  to  the  sympathetic 
branches  in  the  cavernous  sinus.  8.  Part  of  the  sixth  nerve  in  the  cavernous  sinus, 
receiving  two  branches  from  the  carotid  plexus.  9.  Meckel's  ganglion  (spheno-pala- 
tine).  10.  Its  ascending  branches,  communicating  with  the  superior  maxillaiy  nerve. 
11.  Its  descending  branches,  the  posterior  palatine.  12.  Its  anterior  branches,  spheno- 
palatine or  nasal.  19.  The  naso-palatine  branch,  one  of  the  nasal  branches.  *  The 
swelling  which  Cloquet  imagines  to  be  a  ganglion.  14.  The  posterior  branch  of  the 
ganglion,  the  Vidian  nerve.  15.  Its  carotid  branch  communicating  with  the  carotid 
plexus.  16.  Its  petrosal  branch,  joining  the  angular  bend  of  the  facial  nerve.  17.  The 
facial  nerve.  18.  The  chorda  tympani  nerve,  which  descends  to  join  the  gustatory 
nerve.  13.  The  gustatory  nerve.  20.  The  submaxillary  ganglion,  receiving  the  chorda 
tympani  nerve  from  the  gustatory.  21.  The  superior  cervical  ganglion  of  the  sym- 
pathetic. 


CRANIAL  GANGLIA.  427 

anterior  angles  by  two  groups :  tlie  upper  group,  consisting  of  about 
four  filaments  ;  and  the  lower,  of  five  or  six.  They  accompany  the 
ciliary  arteries  in  a  waving  course,  and  divide  into  a  number  of 
branches  which  pierce  the  sclerotic  around  the  optic  nerve,  and 
supply  the  tunics  of  the  eyeball.  A  small  filament  is  said,  by 
Tiedemann,  to  accompany  the  arteria  centralis  retinae  into  the  centre 
of  the  globe  of  the  eye. 

Its  branches  of  communication  are  three  : — 1.  From  the  posterior 
superior  angle  of  the  nasal  branch  of  the  ophthalmic  nerve._  2.  K 
short  thick  branch  from  the  posterior  inferior  angle  to  the  inferior 
division  of  the  third  nerve.  3.  A  long  filament,  which  passes  back- 
wards to  the  cavernous  sinus,  and  communicates  with  the  carotid 
plexus. 

3.  The  Naso-palatine  Ganglion  (Cloquet's),  is  a  small  lengthened 
body,  situated  in  the  naso-palatine  canal.  There  is  no  difficulty  in 
finding  it  in  that  situation.  But  it  is  still  a  question  whether 
it  be  actually  a  ganglion.  Arnold  refuses  to  admit  it  in  his  plates 
of  the  cranial  nerves,  and  denies  its  existence :  Cruveilhier  agrees 
with  him  in  opinion.  Mr.  Charles  Guthrie,  demonstrator  of 
anatomy  in  the  Charing-Cross  School  of  Medicine,  has  recently 
satisfied  himself  of  its  existence  and  of  its  ganglionic  nature.* 

Its  branches  of  distribution  are,  two  or  three  small  filaments  to 
the  anterior  part  of  the  palate, — anterior  palatine  nerves. 

Its  branches  of  communication  are  two  long  delicate  filaments, 
which  ascend  upon  the  septum  narium,  beneath  the  mucous  mem- 
brane, and  pass  across  the  posterior  part  of  the  roof  of  the  nares, 
and  through  the  spleno-palatine  foramina,  to  terminate  in  the  spheno- 
palatine ganglion  at  each  side. 

4.  The  Spheno-palatine  Ganglion  (Meckel's)  the  largest  of  the 
cranial  ganglia  of  the  sympathetic,  is  very  variable  in  its  dimensions. 
It  is  situated  in  the  spheno-maxillary  fossa. 

Its  branches  are  divisible  into  four  groups  ;  ascending,  descending, 
anterior  or  internal,  and  posterior. 

The  branches  of  distribution  are,  the  internal  or  nasal,  four  or 
five  in  number,  which  enter  the  nose  through  the  spheno-palatine 
foramen,  and  supply  the  mucous  membrane  of  the  nares ;  and  the 
descending  or  posterior  palatine  branches,  three  in  number,  which 
pass  downwards  through  the  posterior  palatine  canal^  and  are  dis- 
tributed to  the  mucous  membrane  of  the  nose  and  antrum  maxillare, 
to  the  velum  palati  and  to  the  palate. 

The  branches  of  communication  are  the  ascending,-\  two  small 
branches  which  pass  upwards  to  join  the  superior  maxillary  nerve  ; 
and  the  posterior  branch  or  Vidian  nerve. 

The  VidianX  nerve  passes  directly  backwards  from  the  spheno- 

*  I  have  several  times  dissected  for  this  ganglion,  and  have  as  yet  never  failed  to 
find  it.— G. 

+  Arnold  figures,  in  his  beautiful  plates  of  the  cranial  nerves,  two  small  ascending 
filaments  which  enter  the  orbit  and  join  the  optic  nerve. 

t  Guido  Guidi,  latinized  into  Vidus  Vidius,  was  professor  of  anatomy  and  medicine 
in  the  College  of  France  in  1542.  His  work  is  posthumo'is,  and  was  published  in 
1611. 


428  SUB-MAXILLARY  GANGLION. 

palatine  ganglion,  through  the  pterygoid  or  Vidian  canal,  to  the 
foramen  lacerum  basis  cranii,  where  it  divides  into  two  branches, 
the  carotid  and  petrosal*  The  carotid  branch  enters  the  carotid 
canal,  and  joins  the  carotid  plexus.  The  petrosal  branch  enters  the 
cranium  through  the  foramen  lacerum  basis  cranii,  and  passes 
backwards  beneath  the  Casserian  ganghon,  and  beneath  the  dura 
mater,  lying  in  a  groove  upon  the  anterior  surface  of  the  petrous 
hone,  to  the  hiatus  Fallopii.  Entering  the  hiatus  Fallopii  it  imme- 
diately joins  the  facial  nerve,  just  as  that  cord  is  making  its  angular 
bend,  previously  to  winding  back  along  the  inner  wall  of  the  tympa- 
num.f  The  petrosal  branch  accompanies  the  facial  nerve,  along 
the  aqueeductus  Fallopii,  enclosed  in  its  sheath  to  within  a  few  hnes 
of  the  stylo-mastoid  foramen.  It  then  quits  the  facial  nerve,  return- 
ing upon  itself  at  an  acute  angle,  and  enters  the  tympanum  near  the 
base  of  the  pyramid.  It  now  takes  the  name  of  chorda  tympani  and 
crosses  the  tympanum  enveloped  in  mucous  membrane,  between  the 
handle  of  the  malleus  and  long  process  of  the  incus  to  the  fissura 
Glaseri;  passing  •  through  a  particular  opening  in  this  fissure  it 
descends  upon  the  inner  side  of  the  cond3de  of  the  lower  jaw,  and 
internally  to  the  auricular  and  inferior  dental  nerves  to  the  gusta- 
tory nerve,  which  it  joins  at  an  acute  angle.J  Accompanying  the 
gustatory,  enclosed  in  its  sheath,  to  the  submaxillary  gland,  it  quits 
that  nerve  and  communicates  with  the  submaxillary  ganglion. 

The  petrosal  branch  of  the  Vidian  nerve  receives  a  branch  from 
the  tympanic  nerve  while  in  the  hiatus  Fallopii. 

The  Vidian  nerve  thus  becomes  the  medium  of  communication 
between  the  spheno-palatine  ganglion  and  submaxillary  ganglion ; 
and  between  both  of  these  gangha  and  the  carotid  plexus  ;  and 
through  the  tympanic  nerve  with  the  glosso-pharyngeal  and  pneu- 
mogastric  nerves :  and  if  the  fusion  of  nervous  substance  be  admitted, 
between  the  whole  of  these  and  the  facial,  the  auditory,  and  the 
gustatory  nerves. 

5.  The  Submaxillary  Ganglion  is  of  small  size,  but  very  distinct, 
and  is  situated  in  the  submaxillary  gland. 

Its  branches  of  distribution  are  numerous,  and  ramify  upon  the 
ducts  of  the  gland,  and  upon  Wharton's  duct. 

Its  branches  of  communication  are, — 1,  one  or  two  small  branches 
which  join  the  gustatory  nerve ;  and  2,  several  minute  branches 

*  Or  the  deep  and  superficial  petrous. — G, 

t  Here  two  rival  opinions  clash ;  one  set  of  anatomists,  and  with  them  Swan  and 
Arnold,  believe  that  the  petrosal  branch  unites  with  tlie  substance  of  the  facial  nerve ; 
the  two  latter  writers  even  g^o  so  far  as  to  describe  a  g-angiionie  enlargement  upon  the 
facial  nerve  at  this  point,  and  Arnold  would  seem  to  intimate  that  the  nerve  is  actually 
a  branch  of  this  ganglion;  while  another  set  maintain  that  tlic  petrosal  branch  merely 
accompanies  the  facial  nerve,  being  enclosed  in  its  neurilemma.  As  the  question  is 
yet  litigated,  and  as  I  am  prepared  vvitli  no  positive  proof  to  decide  for  either  party,  I 
shall  at  present  adopt  the  latter  view  as  the  more  convenient  for  description,  and  for 
explaining  the  connexions  between  the  different  cranial  ganglia.  The  latter  opinion 
has  for  its  supporters,  Cloquet,  Ribes,  and  liirzel. 

X  Here,  again,  the  question  effusion  of  nervous  substance,  or  mere  contact,  has  been 
warmly  agitated,  but  with  no  positive  and  unquestionable  results. 


OTIC  GANGLION CAROTID  PLEXUS,  429 

which  communicate  with  the  sympathetic  filaments  ramifying  upon 
the  facial  artery.  It  is  associated  with  the  carotid  plexus,  and 
the  other  cranial  ganglia,  by  means  of  the  petrosal  branch  of  the 
Vidian. 

6.  The  Otic  Ganglion  (Arnold's)*  is  a  small  red  body,  resting 
against  the  inner  surface  of  the  inferior  maxillary  nerve,  imme- 
diately below  the  foramen  ovale;  it  is  in  relation  extern aV y  w\X\\  the 
trunk  of  the  inferior  maxillary  nerve,  just  at  the  point  of  union  of 
the  motor  root;  internally  it  rests  against  the  cartilage  of  the  Eusta- 
chian tube  and  tensor  palati  muscle ;  and  posteriorly  it  is  in  con- 
tact with  the  arteria  meningea  magna.  It  is  closely  adherent  to 
the  internal  pterygoid  nerve,  and  appears  like  a  swelling  upon  that 
branch. 

The  branches  of  the  otic  ganglion  are  seven  in  number ;  two  of 
distribution,  and  five  of  communication. 

The  branches  of  distribution  are, — 1,  a  small  filament  to  the 
tensor  tympani  muscle ;  and,  2,  one  to  the  tensor  palati  muscle. 

The  branches  of  communication  are, — 1,  two  or  three  small 
branches  to  the  motor  root  of  the  inferior  maxillary  nerve ;  2,  two 
branches  to  the  auricular  nerve  :  3,  a  filament  to  the  facial  nerve ; 
4,  a  long  filament,  the  nervous  pelrosus  superficialis  minor  to  com- 
municate with  the  tympanic  nerve  (Jacobson's)  in  the  tympanum ; 
and,  5,  one  or  two  small  branches  which  join  the  sympathetic  fila- 
ments of  the  arteria  meningea  media  artery. 

Carotid  Plexus. — The  ascending  branch  of  the  superior  cervical 
ganglion  enters  the  carotid  canal  with  the  internal  carotid  artery, 
and  divides  into  two  branches,  which  form  several  loops  of  commu- 
nication with  each  other  around  the  artery.  This  constitutes  the 
carotid  'plexus.  They  also  form  frequently  a  small  gangliform  swell- 
ing upon  the  under  part  of  the  artery,  which  is  called  the  carotid 
ganglion.  The  latter,  however,  is  not  constant ;  and,  as  it  performs 
no  special  function,  we  do  not  include  it  amongst  the  cranial  gan- 
gUa  of  the  sympathetic.  The  continuation  of  the  carotid  plexus 
onwards  with  the  artery  by  the  side  of  the  sella  turcica,  is  called  the 
cavernous  plexus. 

The  carotid  plexus  is  the  centre  of  communication  between  all 
the  cranial  ganglia ;  and  being  derived  from  the  superior  cervical 
ganglion,  between  the  cranial  gangUa  and  those  of  the  trunk,  it  also 
communicates  with  the  greater  part  of  the  cerebral  nerves,  and 
distributes  filaments  with  each  of  the  branches  of  the  internal  carotid, 
which  accompany  those  branches  in  all  their  ramifications. 

Thus,  the  Ganglion  of  Ribes  is  formed  by  the  union  of  the  fila- 
ments which  accompany  the  anterior  cerebral  arteries,  and  which 
meet  on  the  anterior  communicating  artery.  The  ciliary  ganglion 
communicates  with  the  plexus  by  means  of  the  long  branch  which 
is  sent  back  to  join  it  in  the  cavernous  sinus.     The  spheno-palatine, 

*  Frederick  Arnold,  "  Dissertatio  Inau;^uralis  de  Parte  Ceplialica  Nervi  Sympa- 
thetici,"     Heidelberg,  1826 ;  and  "Ueber  don  Ohrknoten,"  1828. 


430  CERVICAL  GANGLIA. 

and  with  it  the  naso-palatlne  ganglion,  joins  the  plexus  by  means  of 
the  carotid  branch  of  the  Vidian.  The  submaxillary  ganglion  is 
also  connected  with  it  through  the  Vidian.  And  the  otic  ganglion 
is  brought  in  relation  with  it  by  means  of  the  tympanic  nerve  and 
by  the  Vidian. 

It  communicates  with  the  third  nerve  in  the  cavernous  sinus,  and 
through  the  ciliary  ganglion ;  with  the  Casserian  ganglion ;  with  the 
ophthalmic  division  of  the  fifth  in  the  cavernous  sinus,  and  by  means 
of  the  ciliary  ganglion ;  with  the  superior  maxillary,  through  the 
spheno-palatine  ganglion ;  and  with  the  inferior  maxillary,  through 
the  chorda  tympani  and  Vidian.  It  sends  two  branches  directly  to 
the  sixth  nerve,  which  unite*  with  it  as  it  crosses  the  cavernous 
sinus ;  it  communicates  with  the  facial  and  auditory  nerves,  through 
the  medium  of  the  petrosal  branch  of  the  Vidian ;  and  with  the 
glosso-pharyngeal  and  pneumogastric  nerves,  through  the  nervus 
petrosus  supeijicialis  minor,  a  branch  from  the  otic  ganglion  to  the 
tympanic  nerve. 

CERVICAL  GANGLIA. 

The  Superior  cervical  ganglion  is  long  and  fusiform,  of  a  grayish 
colour,  smooth,  and  of  considerable  thickness,  extending  from  within 
an  inch  of  the  carotid  foramen  in  the  petrous  bone  to  opposite 
the  lower  border  of  the  third  cervical  vertebra.  It  is  in  relation  in 
front  with  the  sheath  of  the  internal  carotid  artery  and  internal 
jugular  vein ;  and  behind  with  the  rectus  anticus  major  muscle. 

Its  branches,  like  those  of  all  the  sympathetic  ganglia  in  the  trunk, 
are  divisible  into  superior,  inferior,  external,  and  internal;  to  which 
may  be  added,  as  proper  to  this  ganglion,  anterior. 

The  superior  is  a  single  branch  which  ascends  by  the  side  of  the 
internal  carotid,  and  divides  into  two  branches ;  one  lying  to  the 
outer  side,  the  other  to  the  inner  side  of  that  vessel.  The  two 
branches  enter  the  carotid  canal,  and  communicate  by  means  of 
several  filaments  sent  from  one  to  the  other,  to  constitute  the  carotid 
plexus. 

The  inferior  or  descending  branch,  sometimes  two,  is  the  cord  of 
communication  with  the  middle  cervical  ganglion. 

The  external  branches  are  numerous,  and  may  be  divided  into 
two  sets:  1,  Those  which  communicate  with  the  glosso-pharyngeal, 
pneumogastric,  and  hypoglossal  nerves ;  and,  2,  those  which  com- 
municate with  the  three  first  cervical  nerves. 

The  internal  branches  are  three  in  number:  1.  Pharyngeal,  to 
assist  in  forming  the  pharyngeal  plexus ;  2.  Laryngeal,  to  join  the 
superior  laryngeal  nerve  and  its  branches;  and,  3.  The  superior 
cardiac  nerve,  or  nervous  superficialis  cordis. 

*  Panizza,  in  his  "  Experimental  Researches  on  the  Nerves,"  denies  this  communi- 
cation, and  states  very  vaguely  that  "  they  are  merely  lost  and  entwined  around  it," — 
Edinburgh  Medical  and  Surgical  Journal,  January  1836. 


CERVICAL  GANGLIA — CARDIAC  NERVES.  431 

The  anterior  branches  accompany  the  carotid  artery  with  its 
branches,  around  which  they  form  intricate  plexuses;  they  are  called, 
from  the  softness  of  their  texture,  nervi  molles. 

The  Middle  cervical  ganglion  (thyroid  ganglion)  is  of  small  size, 
and  sometimes  altogether  wanting.  It  is  situated  opposite  the  fifth 
cervical  vertebra,  and  rests  upon  the  inferior  thyroid  artery.  This 
relation  is  so  constant,  as  to  have  induced  Haller  to  name  it  the 
"  thyroid  ganglion." 

Its  superior  branch,  or  branches,  ascend  to  communicate  with  the 
superior  cervical  ganglion. 

Its  inferior  branches  descend  to  join  the  inferior  cervical  gan- 
glion. 

Its  external  branches  communicate  with  the  third,  fourth,  and 
fifth  cervical  nerves. 

Its  internal  branch  is  the  middle  cardiac  nerve,  nervus  cardiacus 
magnus. 

The  Inferior  cervical  ganglion  (vertebral  ganglion)  is  much  larger 
than  the  preceding,  and  is  constant  in  its  existence.  It  is  of  a  semi- 
lunar form,  and  is  situated  upon  the  base  of  the  transverse  process 
of  the  seventh  cervical  vertebra,  immediately  behind  the  vertebral 
artery :  hence  its  title  to  the  designation  "  vertebral  ganglion.''^ 

Its  superior  branches  communicate  with  the  middle  cervical  gan- 
glion. 

The  inferior  branches  pass  some  before  and  some  behind  the  sub- 
clavian artery,  to  join  the  first  thoracic  gangHon. 

The  external  branches  consist  of  two  sets ;  one  which  communi- 
cates with  the  sixth,  seventh,  and  eighth  cervical  nerves ;  and  one 
which  accompanies  the  vertebral  artery  along  the  vertebral  canal, 
forming  the  vertebral  plexus.  This  plexus  sends  filaments  to  all  the 
branches  given  off  by  the  artery,  and  communicates  in  the  skull 
with  the  filaments  of  the  carotid  plexus  accompanying  the  branches 
of  the  internal  carotid  artery. 

.  The  internal  branch  is  the  inferior  cardiac  nerve,  nervus  cardi- 
acus minor. 

Cardiac  Nerves.* — The  superior  cardiac  nerve  {nervus  super- 
ficialis  cordis)  arises  from  the  lower  part  of  the  superior  cervical 
ganglion;  it  then  descends  the  neck  behind  the  common  carotid 
artery,  and,  parallel  with  the  trachea,  crosses  the  inferior  thyroid 
artery,  and  accompanying  the  recurrent  laryngeal  nerve  for  a  short 
distance,  passes  behind  the  arteria  innominata  to  the  concavity  of 
the  arch  of  the  aorta,  where  it  joins  the  cardiac  ganglion. 

In  its  course  it  receives  branches  from  the  pneumogastric  nerve, 
and  sends  filaments  to  the  thyroid  gland  and  trachea. 

The  Middle  cardiac  nerve  {nervus  cardiacus  magnus)  proceeds 
from  the  middle  cervical  ganglion,  or,  in  its  absence,  from  the  cord 


*  There  is  no  constancy  with  regard  to  the  origin  and  course  of  these  nerves;  there- 
fore the  student  must  not  be  disappointed  in  finding  the  description  in  discord  with  his 
dissection. 


432  CARDIAC  GANGLION — THORACIC  GANGLIA. 

of  communication  between  the  superior  and  inferior.  It  is  the  largest 
of  the  three  nerves,  and  hes  nearly  parallel  with  the  recurrent  laryn- 
geal. At  the  root  of  the  neck  it  divides  into  several  branches,  which 
pass  some  before  and  some  behind  the  subclavian  artery ;  it  com- 
municates with  the  superior  and  inferior  cardiac,  and.  with  the 
pneumogastric  and  recurrent  nerves,  and  descends  to  the  bifurca- 
tion of  the  trachea,  to  the  great  cardiac  plexus. 

The  Inferior  cardiac  nerve  {nerviis  cardiacus  minor)  arises  from 
the  inferior  cervical  gangUon,  communicates  freely  with  the  recur- 
rent laryngeal  and  middle  cardiac  nerves,  and  descends  to  the  front 
of  the  bifurcation  of  the  trachea,  to  join  the  great  cardiac  -plexus. 

The  Cardiac  ganglion  is  a  ganglionic  enlargement  of  variable 
size,  situated  beneath  the  arch  of  the  aorta,  to  the  right  side  of  the 
hgament  of  the  ductus  arteriosus.  It  receives  the  superior  cardiac 
nerves  of  opposite  sides  of  the  neck,  and  a  branch  from  the  pneu- 
moo-astric  nerve,  and  gives  off  numerous  branches  to  the  cardiac 
plexuses. 

The  Great  cardiac  plexus  is  situated  upon  the  bifurcation  of  the 
trachea,  above  the  right  pulmonary  artery,  and  behind  the  arch  of 
the  aorta.  It  is  formed  by  the  convergence  of  the  middle  and 
inferior  cardiac  nerves,  and  by  branches  from  the  pneumogastric 
nerve. 

The  Anterior  cardiac  plexus  is  situated  in  front  of  the  ascending 
aorta,  near  to  its  origin.  It  is  formed  by  the  communications  of 
filaments  that  proceed  from  three  different  sources.  1st,  from  the 
superior  cardiac  nerves,  crossing  the  arch  of  the  aorta ;  2dly,  from 
the  cardiac  ganglion  beneath  the  arch ;  and,  3dly,  from  the  great 
cardiac  plexus, — passing  between  the  ascending  aorta  and  the  right 
auricle.  The  anterior  cardiac  plexus  supplies  the  anterior  aspect 
of  the  heart,  distributing  numerous  filaments  with  the  left  coronary 
artery,  which  form  the  anterior  coronary  plexus. 

The  Posterior  cardiac  plexus  is  formed  by  numerous  branches 
from  the  great  cardiac  plexus,  and  is  situated  upon  the  posterior 
part  of  the  ascending  aorta,  near  to  its  origin.  It  divides  into  two 
sets  of  branches :  one  set  accompanying  the  right  coronary  artery 
in  the  auriculo-ventricular  sulcus ;  the  other  set  joining  the  artery 
on  the  posterior  aspect  of  the  heart.  They  both  together  constitute 
the  posterior  coronary  plexus. 

The  great  cardiac  plexus  likewise  gives  branches  to  the  auricles 
of  the  heart,  and  others,  to  assist  in  forming  the  anterior  and  poste- 
rior pulmonary  plexuses. 

THORACIC  GANGLIA. 

The  Thoracic  ganglia  are  twelve  in  number  on  each  side.  They 
are  flattened  and  triangular,  or  irregular  in  form,  and  present  the 
peculiar  gray  colour  and  pearly  lustre  of  the  other  sympathetic 
ganglia ;  they  rest  upon  the  heads  of  the  ribs,  and  are  covered  in 


SEMILUNAR  GANGLION SOLAR  PLEXUS.  433 

by  the  pleura  costalis.  The  two  first  and  the  last  ganglia  are 
usually  the  largest. 

Their  brandies  are  superior,  inferior,  external  and  internal. 

The  superior  and  inferior  are  prolongations  of  the  substance  of 
the  ganglia  rather  than  branches ;  the  former  to  communicate  with 
the  o-ano;lion  above,  the  latter  wdth  that  below. 

The  external  branches,  two  or  three  in  number,  communicate  witii 
each  of  the  spinal  nerves. 

The  ijiternal  branches  of  the  five  upper  ganglia  are  aortic,  and 
follow  the  course  of  the  intercostal  arteries  to  that  trunk:  the 
branches  of  the  lower  ganglia  unite  to  form  the  two  splanchnic 
nerves. 

The  Great  splanchnic  nerve  arises  from  the  sixth  dorsal  ganglion, 
and  receives  branches  from  the  seventh,  eighth,  ninth,  and  tenth, 
which  increase  it  to  a  nerve  of  considerable  size.  It  descends  in 
front  of  the  vertebral  column,  within  the  posterior  mediastinum, 
pierces  the  diaphragm  immediately  to  the  outer  side  of  each  crus, 
and  terminates  in  the  semilunar  ganglion. 

The  Lesser  splanchnic  nerve  {renal)  is  fornied  by  filaments  from 
the  tenth,  eleventh,  and  sometimes  from  the  twelfth  dorsal  ganglion. 
It  pierces  the  diaphragm,  and  descends  to  join  the  renal  plexus. 

The  Semilunar  ganglion  is  a  large,  irregular,  gangliform  body, 
pierced  by  numerous  openings,  and  appearing  like  the  aggregation 
of  a  number  of  smaller  ganglia,  having  spaces  between  them.  It  is 
situated  by  the  side  of  the  cceliac  axis,  and  communicates  with  the 
ganglion  of  the  opposite  side,  both  above  and  below  that  trunk,  so 
as  to  form  a  gangliform  circle,  from  which  branches  pass  off  in  all 
directions,  like  rays  from  a  centre.  Hence  the  entire  circle  has 
been  named  the  solar  plexus. 

The  Solar  plexus  receives  the  gi'eat  splanchnic  nerves ;  part  of 
the  lesser  splanchnic  nerves ;  the  termination  of  the  right  pneumo- 
gastric  nerve ;  some  branches  from  the  right  phrenic  nerve ;  and 
sometimes  one  or  two  filaments  from  the  left.  It  gives  oft"  nume- 
rous  filaments,  which  accompany,  under  the  name  of  plexuses,  all 
the  branches  given  oft'  by  the  abdominal  aorta.  Thus,  we  have 
derived  from  the  solar  plexus  the — 

Phrenic  plexuses, 
Gastric  plexus, 
Hepatic  plexus, 
Splenic  plexus. 
Supra-renal  plexuses, 
Renal  plexuses, 
Supei'ior  mesenteric  plexus, 
Spermatic  plexuses, 
Inferior  mesenteric  plexus. 

The  Renal  plexus  is  formed  chiefty  by  the  lesser  splanchnic  nerve, 
but  receives  many  filaments  from  the  solar  plexus. 

55 


434  LUMBAK  AND  SACRAL  GANGLIA. 

The-  Spermatic  plexus  is  formed  principally  by  the  renal  plexus. 
The  Inferioi'  mesenteric  plexus  receives  filaments  from  the  aortic 
plexus. 

LUMBAR  GANGLIA. 

The  Lumhar  ganglia  are  four  in  number  on  each  side,  of  the 
peculiar  pearly  gray  colour,  fusiform,  and  situated  upon  the  ante- 
rior part  of  the  bodies  of  the  lumbar  vertebrae. 

The  superior  and  inferior  branches  of  the  lumbar  ganglia  are 
branches  of  communication  with  the  ganglion  above  and  below,  as 
in  the  dorsal  region. 

The  external  branches,  two  or  three  in  number,  communicate 
with  the  lumbar  nerves. 

The  internal  branches  consist  of  two  sets ;  of  which  the  upper 
pass  inwards  in  front  of  the  abdominal  aorta,  and  form  around  that 
trunk  a  plexiform  interlacement,  which  constitutes  the  aortic  plexus  ; 
the  lower  branches  cross  the  common  iliac  arteries,  and  unite  over 
the  promontory  of  the  sacrum,  to  form  the  hypogastric  plexus. 

The  Jiortic  plexus  is  formed  by  branches  from  the  lumbar  ganglia, 
and  receives  filaments  from  the  solar  and  superior  mesenteric 
plexuses.  It  sends  filaments  to  the  inferior  mesenteric  plexus,  and 
terminates  in  the  hypogastric  plexus. 

The  Hypogastric  plexus  is  formed  by  the  termination  of  the  aortic 
plexus,  and  by  the  union  of  branches  from  the  lower  lumbar  gan- 
gha.  It  is  situated  over  the  promontory  of  the  sacrum,  between  the 
two  common  iliac  arteries,  and  bifurcates  inferiorly  into  two  lateral 
portions,  which  communicate  with  branches  from  the  fourth  and 
fifth  sacral  nerves.  It  distributes  branches  to  all  the  viscera  of  the 
pelvis,  and  to  the  branches  of  the  internal  iliac  artery. 

SACRAL  GANGLIA. 

The  Sacral  ganglia  are  four  or  five  in  number  on  each  side.  They 
are  situated  upon  the  sacrum,  close  to  the  anterior  sacral  foramina, 
and  resemble  the  lumbar  ganglia  in  form  and  mode  of  connexion, 
although  they  are  much  smaller  in  size. 

The  superior  and  inferior  branches  communicate  with  the  gan- 
glia above  and  below. 

The  external  branches  communicate  with  the  sacral  and  coccygeal 
nerves. 

The  internal  branches  communicate  very  freely  with  the  lateral 
divisions  of  the  hypogastric  plexus,  and  arc  distributed  to  the  pelvic 
viscera.  The  last  sacral  ganglia  of  the  opposite  sides  give  off 
branches  which  join  a  small  ganglion,  situated  on  the  first  bone  of  the 
coccyx,  called  tlie  ganglion  impar,  or  axygos.  This  ganglion  resem- 
bles in  its  position  and  function  the  ganglion  of  Ribcs,  serving  to 
connect  the  inferior  extremity  of  the  syn)pathetic  system,  as  does 
the  former  ganglion  its  upper  extremity.  It  gives  ofll"  a  few  small 
branches  to  the  coccyx  and  rectum. 


CHAPTER   IX. 


ORGANS  OF  SENSE. 


The  organs  of  sense,  the  instruments  by  which  the  animal  frame 
is  brought  into  relation  with  surrounding  nature,  are  five  in  number. 
Four  of  these  organs  are  situated  within  the  head,  viz.  the  apparatus 
of  smell,  sight,  hearing,  and  taste,  and  the  remaining  organ,  of  touch, 
is  resident  in  the  skin,  and  is  distributed  over  the  entire  surface  of 
the  body. 

THE  NOSE  AND  NASAL  FOSS^. 

The  organ  of  smell  consists  essentially  of  two  parts :  one  exter- 
nal, the  nose ;  the  other  internal,  the  nasal  fossce. 

The  nose  is  the  triangular  pyramid  projecting  from  the  centre  of 
the  face,  immediately  above  the  upper  lip.  Superiorly,  it  is  con- 
nected with  the  forehead,  by  means  of  a  narrow  bridge ;  inferiorly, 
it  presents  two  openings,  the  nostrils,  which  overhang  the  mouth, 
and  are  so  constructed  that  the  odour  of  all  substances  must  be  re- 
ceived by  the  nose  before  they  can  be  introduced  within  the  lips. 
The  septum  between  the  openings  of  the  nostrils  is  called  the  columna. 
Their  entrance  is  guarded  by  a  number  of  stiff  hairs  {vibrissce), 
which  project  across  the  openings,  and  act  as  a  filter  in  preventing 
the  introduction  of  foreign  substances,  such  as  dust  or  insects,  with- 
the  current  of  air  intended  for  respiration. 

The  anatomical  elements  of  which  the  nose  is  composed  are, — 1. 
Integument.  2.  Muscles.  3.  Bones.  4.  Fibro-cartilages.  5.  Mu- 
cous membrane.     6.  Vessels  and  nerves. 

1.  The  Integument  forming  the  tip  (lobulus)  and  wings  (alee)  of 
the  nose  is  extremely  thick  and  dense,  so  as  to  be  with  difficulty 
separated  from  the  fibro-cartilage.  It  is  furnished  with  a  number 
of  sebaceous  follicles,  which  by  their  oily  secretion,  protect  the  ex- 
tremity of  the  nose  in  excessive  alternations  of  temperature.  The 
sebaceous  matter  of  these  follicles  becomes  of  a  dark  colour  upon 
the  surface,  from  the  attraction  of  the  carbonaceous  matter  floating 
in  the  atmosphere :  hence  the  spotted  appearance  which  the  tip  of 
the  nose  presents  in  large  cities.  When  the  integument  is  firmly 
compressed,  the  inspissated  sebaceous  secretion  is  squeezed  out 
from  the  follicles,  and  taking  the  cylindrical  form  of  their  excretory 
ducts,  has  the  appearance  of  small  white  maggots  with  black  heads. 


436 


CAIfTILAGES  OF  THE  NOSE. 


2.  The  Muscles  are  brought  into  view  by  reflecting  the  integu- 
ment :  they  are  the  pyramidaUs  nasi,  compressor  nasi,  levator  labii 
superioris  alffique  nasi,  and  depressor  labii  superioris  alaeque  nasi. 
They  have  been  already  described  with  the  muscles  of  the  face. 

3.  The  Bones  of  the  nose  are  the  nasal,  and  nasal  processes  of 
the  superior  maxillary. 

4.  The  Fibro-cartilages  give  form  and  stability  to  the  outwork  of 
the  nose,  providing  at  the  same  time,  by  their  elasticity,  against  in- 
juries.    They  are  five  in  number,  the 

Fibro-cartilage  of  the  septum, 
Two  lateral  fibro-cartilages. 
Two  alar  fibro-cartilages. 

The  Fibro-cartilage  of  the  septum,  somewhat  triangular  in  form, 
divides  the  nose  into  its  two  nostrils.  It  is  connected  above  with 
the  nasal  bones  and  lateral  fibro-cartilages ;  behind,  with  the  eth- 
moidal septum  and  vomer ;  and,  below,  with  the  palate  processes  of 
the  superior  maxillary  bones.  The  alar  fibro-cartilages  and  columna 
move  freely  upon  the  fibro-cartilage  of  the  septum,  being  but  loosely 
connected  with  it  by  perichondrium. 

The  Lateral  fibro-cartilages  are  also  trian- 
gular :  they  are  connected,  in  front,  with  the 
fibro-cartilage  of  the  septum ;  above  with  the 
nasal  bones  ;  behind  with  the  nasal  processes 
of  the  superior  maxillary  bones ;  and  belaiv 
with  the  alar  fibro-cartilages. 

Alar  fibro-cartilages. — Each  of  these   carti- 
lages is  curved  in  such  a  manner  as  to  corre- 
spond with  the  opening  of  the  nostril,  to  which 
it  forms  a  kind  of  rim.     The  inner  portion  is 
loosely  connected  with  the  same  part  of  the 
opposite  cartilage,  so  as  to  form  the  columna. 
It  is  expanded  and  thickened  at  the  point  of  the 
nose  to  constitute  the  lobe ;  and,  upon  the  side 
fe  forms  a  curve  corresponding  with  the  form  of 
the  ala.     This  curve  is  prolonged  downwards 
and  forwards  in  the  direction  of  the  posterior 
border  of  the  ala  by  three  or  four  small  fibro- 
cartilaginous plates,  which  are  appendages  to  the  alar  fibro-carti- 
lage. 

The  whole  of  these  fibro-cartilages  are  connected  with  each 
other,  and  to  the  bones,  by  perichondrium,  which,  from  its  mem- 
branous structure,  permits  of  the  freedom  of  motion  existing  between 
them. 


Fig.  135* 


-Jry^^ 


*  The  fibro-cartilages  of  the  nose.  1.  The  nasal  bones.  2.  The  fibre  cartilage 
of  the  septurn.  3.  The  lateral  fibro-cartilages.  4.  The  alar  fibro-cartilages.  5. 
The  central  portions  of  the  alar  fibro-cartilages  which  constitute  the  columna.  G,  The 
appendix  of  the  alar  fibro-cartilage.     7.  The  nostrils. 


NASAL  FOSSiE.  437 

5.  The  Mucous  membrane,  lining  the  interior  of  the  nose,  is  con- 
tinuous with  the  sldn  externally,  and  with  the  pituitary  membrane 
of  the  nasal  fossae  within.  Around  the  entrance  of  the  nostrils  it  is 
provided  with  num.erous  vibrisscs. 

6.  Vessels  and  Nerves. — The  Arteries  of  the  nose  are  the  lateralis 
nasi  from  the  facial,  and  the  nasalis  septi  from  the  superior  coro- 
nary. 

Its  JVerves  are  the  facial,  infra-orbital,  and  nasal  branch  of  the 
ophthalmic. 

NASAL  FOSS^. 

To  obtain  a  good  view  of  the  nasal  fosses,  the  face  must  be  di- 
vided through  the  nose  by  a  vertical  incision,  a  little  to  one  side  of 
the  middle  line. 

The  JVasal  fosscB  are  two  irregular,  compressed  cavities,  extend- 
ing backwards  from  the  nose  to  the  pharynx.  They  are  bounded 
superiorhj  by  the  sphenoid  and  ethmoid  bones.  Inferiorhj  by  the 
hard  palate  ;  and  in  the  middle  line  they  are  separated  from  each 
other  by  a  bony  and  fibro-cartilaginous  septum.  A  plan  of  the 
boundaries  of  the  nasal  fossse  will  be  found  at  page  62. 

Upon  the  outer  wall  of  each  fossa,  in  the  dried  skull,  are  three 
projecting  processes,  termed  spongy  bones.  The  two  superior  belong 
to  the  ethmoid,  the  inferior  is  a  separate  bone.  In  the  fresh  fossse 
these  are  covered  with  mucous  membrane,  and  serve  to  increase  its 
surface  by  their  projection  and  by  their  convoluted  form.  The  space 
intervening  between  the  superior  and  middle  spongy  bones  is  the 
superior  meatus ;  the  space  between  the  middle  and  inferior  bones 
is  the  middle  meatus ;  and  that  between  the  inferior  and  the  floor  of 
the  fossa  is  the  inferior  meatus. 

These  meatuses  are  passages  which  extend  from  before  backwards, 
and  it  is  in  rushing  through  and  amongst  these  that  the  atmosphere 
deposits  its  odorant  particles  upon  the  mucous  membrane.  There 
are  several  openings  into  the  nasal  fossa :  thus,  in  the  superior 
meatus  are  the  openings  of  the  sphenoidal  and  posterior  ethmoidal 
cells,  in  the  middle  the  anterior  ethmoidal  cells,  the  frontal  sinuses, 
and  the  antrum  maxillare ;  and,  in  the  inferior  meatus,  the  termina- 
tion of  the  nasal  duct.  In  the  dried  bone  there  are  two  additional 
openings,  the  spheno-palatine  and  the  anterior  palatine  foramen ;  the 
former  being  situated  in  the  superior,  and  the  latter  in  the  inferior 
meatus. 

The  Mucous  membrane  of  the  nasal  fossse  is  called  pituitary,  or 
Schneiderian.*  The  former  name  being  derived  from  its  secretion, 
the  latter  from  Schneider,  who  was  the  first  to  show  that  the  secre- 
tion of  the  nose  proceeded  from  the  mucous  membrane,  and  not 
from  the  brain,  as  was  formerly  imagined.  It  is  continuous  with 
the  general  gastro-pulmonary  mucous  membrane,  and  may  be  traced 

*  Conrad  Victor  Sclincider,  Professor  of  Medicine  at  Wittenberg.  His  work,|_en- 
titled  Dc  Catarrhis,  Slc.  was  published  in  1661. 


438  EYE SCLEROTIC  COAT, 

through  the  openings  in  the  meatuses,  into  the  sphenoidal  and  eth- 
moidal cells  ;  into  the  antrum  maxillare  ;  through  the  nasal  duct  to 
the  surface  of  the  eye,  where  it  is  continuous  with  the  conjunctiva ; 
along  the  Eustachian  tubes  into  the  tympanum  and  mastoid  cells,  to 
which  it  forms  the  Uning  membrane ;  and  through  die  posterior  nares 
into  the  pharnyx  and  mouth,  and  thence  through  the  lungs  and  ali- 
mentary canal. 

The  surface  of  this  membrane  is  furnished  with  a  columnar  epi- 
thelium supporting  innumerable  vibratile  cilia. 

Vessels  and  Nerves. — The  Arteries  of  the  nasal  fossee  are  the 
anterior  and  posterior  ethmoidal,  from  the  ophthalmic  artery ;  and 
spheno-palatine  and  pterygo-palatine  from  the  internal  maxillary. 

The  JVerves  are,  the  olfactory,  the  spheno-palatine  branches 
from  Meckel's  ganglion,  and  the  nasal  branch  of  the  ophthalmic. 
The  ultimate  filaments  of  the  olfactory  nerve  terminate  in  minute 
papillae. 

THE  EYE,  WITH  ITS  APPENDAGES. 

The  form  of  the  eyeball  is  that  of  a  sphere,  of  about  one  inch  in 
diameter,  having  the  segment  of  a  smaller  sphere  ingrafted  upon  its 
anterior  surface,  which  increases  its  antero-posterior  diameter.  The 
axes  of  the  two  eyeballs  are  parallel  with  each  other,  but  do  not  cor- 
respond with  the  axes  of  the  orbits,  which  are  directed  outwards. 
The  optic  nerves  follow  the  direction  of  the  orbits,  and  therefore 
enter  the  eyeballs  to  their  nasal  side. 

The  Globe  of  the  Eye  is  composed  of  tunics  and  of  refracting 
media  called  humours.     The  tunics  are  three  in  number,  the 

1.  Sclerotic  and  Cornea, 

2.  Choroid,  Iris,  and  Ciliary  processes, 

3.  Retina  and  Zonula  ciliaris. 

The  humours  are  also  three — 

Aqueous, 
Crystalline  (lens), 
Vitreous. 

1.  The  Sclerotic  and  Cornea  form  the  external  tunic  of  the  eye- 
ball, and  give  to  it  its  peculiar  form.  Four-fifths  of  the  globe  are 
invested  by  the  sclerotic,  the  remaining  fifth  by  the  cornea. 

The  Sclerotic  (tfxX7]^o^,  hard)  is  a  dense  fibrous  membrane,  thicker 
behind  than  in  front.  It  is  continuous,  posteriorly,  with  the  sheath 
of  the  optic  nerve,  which  is  derived  from  the  dura  mater,  and  it  is 
pierced  by  that  nerve  as  well  as  by  the  ciliary  nerves  and  arteries. 
Anteriorly  it  presents  a  bevelled  edge  which  receives  the  cornea  in 
the  same  way  that  a  watch-glass  is  received  by  the  groove  in  its 


CRYSTALLINE  AND  VITREOUS  HUMOUR. 


439 


case.  Its  anterior  surface  is  covered  by  a  thin  tendinous  layer,  the 
tunica  albuginea,  derived  from  the  expansion  of  the  tendons  of  the 
four  recti  muscles.  By  its  posterior  surface  it  gives  attachment  to  the 
tw^o  oblique  muscles.  The  tunica  albuginea  is  covered,  for  a  pjart  of 
its  extent,  by  the  mucous  membrane  of  the  front  of  the  eye,  the 
conjunctiva ;  and,  by  reason  of  the  brilliancy  of  its  whiteness,  gives 
occasion  to  the  common  expression,  "  the  white  of  the  eye." 

At  the  entrance  of  the  optic  nerve  the  sclerotic  forms  a  thin 
cribriform  lamella  {lamina  cribrosa),  which  is  pierced  by  a  number 
of  minute  openings  for  the  passage  of  the  nervous  filaments.  One 
of  these  openings,  larger  than  the  rest,  and  situated  in  the  centre  of 
the  lamella,  is  the  porus  opticus,  through  which  the  arteria  centralis 
retinae  enters  the  eye. 

Fig-.  136.« 


The  Cornea  (corneus,  horny)  is  the  transparent  projecting  layer 
that  forms  the  anterior  fifth  of  the  globe  of  the  eye.  In  its  form  it 
is  circular,  concavo-convex,  and  resembles  a  watch-glass.  It  is 
received  by  its  edge,  which  is  sharp  and  thin,  within  the  bevelled 
border  of  the  sclerotic,  to  which  it  is  very  fii'mly  attached,  and  it  is 
somewhat  thicker  than  the  anterior  portion  of  that  tunic.     When 


*  A  longitudinal  section  of  the  globe  of  the  eye.  1.  The  sclerotic,  thicker  bcliind  than 
in  front.  2.  The  cornea,  received  within  the  anterior  margin  of  the  sclerotic,  and  con- 
nected with  it  by  means  of  a  bevelled  edge.  3.  The  choroid,  connected  anteriorly  with 
(4)  the  ciliary  ligament,  and  (5)  the  ciliary  processes.  6.  The  iris.  7.  The  pupil.  8. 
The  third  layer  of  the  eye,  the  retina,  terminating  anteriorly  by  an  abrupt  border  at  the 
commencement  of  the  ciliary  processes.  9.  The  canal  of  Petit,  which  encircles  the  lens 
(12) ;  the  thin  layer  in  front  of  this  canal  is  tlie  zonula  ciliaris,  a  prolongation  of  the 
vascular  layer  of  the  retina  to  the  lens.  10.  The  anterior  chamber  of  the  eye  contain- 
ing the  aqueous  humour ;  the  lining  membrane  by  which  the  humour  is  secreted  is 
represented  in  the  diagram.  11.  The  posterior  chamber.  12.  The  lens,  more  conve.v 
behind  than  before,  and  enclosed  in  its  proper  capsule.  13.  The  vitreous  humour 
enclosed  in  the  hyaloid  membrane,  and  in  cells  formed  in  its  interior  by  that  membrane. 
14.  A  tubular  sheath  of  the  hyaloid  membrane,  which  serves  for  the  passage  of  the 
artery  of  the  capsule  of  the  lens.  15.  The  neurilemma  of  the  optic  nerve.  16.  The 
arteria  centralis  retinas,  embedded  in  its  centre. 


440  STRUCTURE  OF  THE  CORNEA. 

examined  from  the  exterior,  its  vertical  diameter  is  seen  to  be  about 
one-sixteenth  shorter  than  the  transverse,  in  consequence  of  the 
overlapping  above  and  below,  of  the  margin  of  the  sclerotica ;  on 
the  interior,  however,  its  outline  is  perfectly  circular. 

The  cornea  is  composed  of  four  layers,  1,  of  the  conjunctiva;  2, 
of  the  cornea  proper,  which  consists  of  several  thin  lamelloe  con- 
nected together  by  an  extremely  fine  cellular  tissue;  3,  of  the  cornea 
elastica,  a  "  fine,  elastic,  and  exquisitely  transparent  membrane, 
exactly  applied  to  the  inner  surface  of  the  cornea  proper ;"  and  4, 
of  the  lining  membrane  of  the  anterior  chamber  of  the  eyeball.  The 
cornea  elastica  is  remarkable  for  its  perfect  transparency,  even 
when  submitted  for  many  days  to  the  action  of  water  or  alcohol ; 
while  the  cornea  proper  is  rendered  perfectly  opaque  by  the  same 
immersion.  To  expose  this  membrane,  Dr.  Jacob  suggests  that  the 
eye  should  be  placed  in  water  for  six  or  eight  days,  and  then  that 
all  the  opaque  cornea  should  be  removed  layer  after  layer.  Another 
character  of  the  cornea  elastica  is  its  great  elasticity,  which  causes 
it  to  roll  up  when  divided  or  torn,  in  the  same  manner  with  the  cap- 
sule of  the  lens.  The  use  of  this  layer,  according  to  Dr.  Jacob,  is 
to  "preserve  the  requisite  permanent  correct  curvature  of  the 
flaccid  cornea  proper." 

The  opacity  of  the  cornea,  produced  by  pressure  on  the  globe, 
results  from  the  infiltration  of  fluid  into  the  cellular  tissue  connect- 
ing its  layers.  This  appearance  cannot  be  produced  in  a  sound 
living  eye. 

Dissection. — The  sclerotic  and  cornea  are  now  to  be  dissected 
away  from  the  second  tunic ;  this,  with  care,  may  be  easily  per- 
formed, the  only  connexions  subsisting  between  them  being  at  the 
circumference  of  the  iris,  the  entrance  of  the  optic  nerve,  and  the 
perforation  of  the  ciliary  nerves  and  arteries.  Pinch  up  a  fold  of 
the  sclerotic  near  its  anterior  circumference,  and  make  a  small 
opening  into  it,  then  raise  the  edge  of  the  tunic,  and  with  a  pair  of 
fine  scissors,  having  a  probe  point,  divide  the  entire  circumference 
of  the  sclerotic,  and  cut  it  away  bit  by  bit.  Then  separate  it  from 
its  attachment  around  the  circumference  of  the  iris  by  a  gentle 
pressure  with  the  edge  of  the  knife.  The  dissection  of  the  eye  must 
be  conducted  under  water. 

In  the  course  of  this  dissection  the  ciUary  nerves  and  long  ciliary 
arteries  will  be  seen  passing  forwards  between  the  sclerotic  and 
choroid,  to  be  distributed  to  the  iris. 

2.  Second  tunic. — Tlie  second  tunic  of  the  eyeball  is  formed  by 
the  choroid,  ciliary  ligament  and  ins,  the  ciliary  processes  being  an 
appendage' developed  from  its  inner  surface. 

The  choroid*  is  a  vascular  membrane  of  a  rich  chocolate-brown 

*  Tho  word  choroid  has  been  very  much  abused  in  anatomical  lanj^uaa^e ;  it  was 
originally  applied  to  tho  membrane  of  the  foetus  called  chorion  from  tho  Greek  word 
X^fiov,  domicilium,  that  membrane  being,  as  it  were,  the  abode  or  recc])taelc  of  the 
foDtuf.  Y^oftov  comes  from  ^ceptce,  to  take  or  receive.  Now  it  so  happens  that  the  cho- 
rion in  the  ovum  is  a  vascular  membrane  of  a  peculiar  structure.      Hence  the  term 


CILIARY  LIGAMENT.  441 

colour  upon  its  external  surface,  and  of  a  deep  black  colour  within. 
It  is  connected  to  the  sclerotic,  externally,  by  an  extremely  fine  cel- 
lular tissue,  and  by  the  passage  of  nerves  and  vessels.  Internally 
it  is  in  simple  contact  with  the  third  tunic  of  the  eye,  the  retina.  It 
is  pierced  posteriorly  for  the  passage  of  the  optic  nerve,  and  is  con- 
nected anteriorly  with  the  iris,  ciliary  processes,  and  with  the  line 
of  junction  of  the  cornea  and  sclerotic,  by  a  dense  white  structure, 
the  ciliary  ligament,  which  surrounds  the  circumference  of  the  iris 
like  a  ring. 

The  choroid  membrane  is  composed  of  three  layers : — 1.  An 
external  or  venous,  which  consists  principally  of  veins  arranged  in 
a  peculiar  manner :  hence  they  have  been  named  vencB  vorticosce. 
The  marking  upon  the  surface  of  the  membrane  produced  by  these 
veins,  resembles  so  many  centres,  to  which  a  number  of  curved 
lines  converge.  It  is  this  layer  which  is  connected  with  the  ciliary 
ligament.  2.  The  middle  or  arterial  layer  {tunica  Ruyschiana*)  is 
formed  principally  by  the  ramifications  of  minute  arteries,  and 
secretes  upon  its  surface  the  pigmentum  nigrum.  It  is  reflected 
inwards  at  its  junction  with  the  ciliary  ligament,  so  as  to  form  the 
ciliary  processes.  3.  The  internal  layer  is  a  delicate  membrane 
(membrana  figmenti)  which  presents  a  beautiful  appearance  beneath 
the  microscope ;  it  is  composed  of  several  laminae  of  nucleated 
hexagonal  cells,  which  contain  the  granules  of  pigmentum  nigrum, 
and  are  arranged  so  as  to  resemble  a  tesselated  pavement. 

In  animals  the  pigmentum  nigrum,  upon  the  posterior  wall  of  the 
eyeball,  is  replaced  by  a  layer  of  considerable  extent,  and  of  metallic 
brilliancy,  called  the  tapetum. 

The  ciliary  ligament,  or  circle,  is  the  bond  of  union  between  the 
external  and  middle  tunics  of  the  eye,  and  serves  to  connect  the 
cornea  and  sclerotic  at  their  fine  of  junction  with  the  iris  and  ex- 
ternal layer  of  the  choroid.  It  is  also  the  point  to  which  the  ciliary 
nerves  and  vessels  proceed  previously  to  their  distribution,  and  it 
receives  the  anterior  ciliary  arteries  through  the  anterior  margin  of 
the  sclerotic.  A  minute  vascular  canal  is  situated  within  the  ciliary 
ligament,  called  the  ciliary  canal,  or  the  canal  of  Fontana,f  from 
its  discoverer. 

The  Iris  (iris,  a  rainbow)  is  so  named  from  its  variety  of  colour 
in  different  individuals :  it  forms  a  septum  between  the  anterior  and 
posterior  chambers  of  the  eye,  and  is  pierced  somewhat  to  the  nasal 
side  of  its  centre  by  a  circular  opening,^  which  is  called  the  pupil. 

choroid,  ;^''/j/ov  e/tfoc,  like  the  chorion,  has  been  used  indiscriminately  to  signify  vas- 
cular structures,  as  in  the  choroid  membrane  of  the  eye,  the  choroid  plexus,  ifcc.  and 
we  find  Cruveilhier  in  his  admirable  work  on  Anatomy,  vol.  iii.  p.  463,  saying  in  a  note, 
"  Choroide  est  synonymc  de  vasculeuse." 

*  Ruysch  was  born  at  the  Hague  in  1638,  and  was  appointed  professor  of  Anatomy 
at  Amsterdam  in  1665.  His  whole  life  was  employed  in  making  injected  preparations, 
for  wliich  he  is  justly  celebrated.  He  came  to  the  conclusion  that  the  body  was  en- 
tirely made  up  of  vessels.     He  died  at  the  advanced  age  of  ninety-three  years. 

t  Felix  Fontana,  an  anatomist  of  Tuscany.  His  "  Description  of  a  New  Canal  in 
the  Eye,"  was  published  in  1778,  in  a  letter  to  the  Professor  of  Anatomy  in  Upsal. 

56 


442 


IRIS CILIARY  PROCESSES, 


By  its  periphery  it  is  connected  with  the  ciliary  ligament,  and  by  its 
inner  circumference  forms  the  margin  of  the  pupil :  its  anterior  sur- 
face looks  towards  the  cornea,  and  the  posterior  towards  the  ciliary 
processes  and  lens. 

It  is  composed  of  two  layers,  an  anterior  or  muscular,  consisting 
of  radiating  fibres  which  converge  from  the  circumference  towards 
the  centre,  and  have  the  power  of  dilating  the  pupil ;  and  circular, 

which    surround   the   pupil  like   a 
Fig.  137.*  sphincter,  and  by  their  action  pro- 

;/  duce  contraction  of  its  area.     The 

posterior  layer  is  of  a  deep  purple 
tint,  and  is  thence  named  uvea, 
from  its  resemblance  in  colour  to 
a  ripe  grape. 

The  Ciliary  processes  may  be 
seen  in  two  ways,  either  by  re- 
moving the  iris  from  its  attachment 
to  the  ciliary  ligament,  when  a  front 
view  of  the  processes  will  be  ob- 
tained, or  by  making  a  transverse 
section  through  the  globe  of  the  eye, 
when  they  may  be  examined  from 
behind,  as  in  fig.  137. 
The  ciHary  processes  consist  of  a  number  of  triangular  folds, 
formed  apparently  by  the  plaiting  of  the  internal  layer  of  the  cho- 
roid. They  are,  according  to  Zinn,  about  sixty  in  number,  and  may 
be  divided  into  large  and  small,  the  latter  being  situated  in  the 
spaces  between  the  former.  The  periphery  is  connected  with  the 
ciliary  ligament,  and  is  continuous  with  the  internal  layer  of  the 
choroid.  The  central  border  is  free,  and  rests  against  the  circum- 
ference of  the  lens.  The  anterior  surface  corresponds  with  the 
uvea ;  the  posterior  receives  the  folds  of  the  zonula  ciliaris  between 
its  processes,  and  thus  establishes  a  connexion  between  the  choroid 
and  the  third  tunic  of  the  eye.  The  ciliary  processes  are  covered 
with  a  thick  layer  of  pigmentum  nigrum,  which  is  more  abundant 
upon  them,  and  upon  the  anterior  part  of  the  choroid,  than  upon 
the  posterior.  When  the  pigment  is  washed  off,  the  processes  are 
of  a  whitish  colour. 

3.  Third  tunic. — The  third  tunic  of  the  eye  is  the  retina,  which 
is  prolonged  forwards  to  the  lens  by  the  zonula  ciliaris. 

Dissection. — If  after  the  preceding  dissection  the  choroid  mem- 
brane be  carefully  raised  and  removed,  the  eye  being  kept  under 
water,  the  retina  may  be  seen  very  distinctly. 
The  Retina  is  composed  of  three  layers : — 


*  The  anterior  segment,  of  a  transverse  section  of  the  globe  of  the  eye,  seen  from 
within.  1.  The  divided  edge  of  the  three  tunics  ;  sclerotic,  choroid  (the  dark  layer,) 
and  retina.  2.  the  pupil.  3.  The  iris,  the  surface  presented  to  view  in  this  section 
being  the  uvea.  4.  The  ciliary  processes.  .'3.  Tiic  scalloped  anterior  border  of  the 
retina. 


RETINA STRUCTURE. 


443 


External  or  Jacob's  membrane, 
Middle,  Nervous  membrane, 

Internal,        Vascular  membrane. 

Jacob's  memhrane  is  extremely  thin,  and  is  seen  as  a  flocculent 
film  when  the  eye  is  suspended  in  water.  Examined  by  the  micro- 
scope, it  is  seen  to  be  composed  of  granules  having  a  tesselated 
arrangement.     Dr.  Jacob  considers  it  to  be  a  serous  membrane. 

The  Nervous  memhrane  is  the  expansion  of  the  optic  nerve,  and 
forms  a  thin  semi-transparent  bluish  white  layer,  which  envelopes 
the  vitreous  humour,  and  extends  forwards  to  the  commencement 
of  the  ciliary  processes,  where  it  terminates  in  an  abrupt  scalloped 
margin. 

This  layer  has  been  observed  by  Treviranus  to  be  composed  of 
cylindrical  fibres,  which  proceed  from  the  optic  nerve  and  bend 
abruptly  inwards,  near  their  termination,  to  form  the  internal  papil- 
lary layer,  which  lies  in  contact  with  the  hyaloid  membrane  ;  each 
fibre  constituting  by  its  extremity  a  distinct  papilla. 

The  Vascular  memhrane  consists  of  the  ramifications  of  a  minute 
artery,  the  arteria  centralis  retinae,  and  its  accompanying  vein ;  the 
artery  pierces  the  optic  nerve,  and  enters  the  globe  of  the  eye 
through  the  porus  opticus  in  the  centre  of  the  lamina  cribrosa.  This 
artery  may  be  seen  very  distinctly  by  making  a  transverse  section 
of  the  eyeball.  Its  branches  are 
continuous  anteriorly  with  the  zo- 
nula ciliaris. 

This  vascular  layer  forms  distinct 
sheaths  for  the  nervous  papillae, 
which  constitute  the  inner  surface 
of  the  retina. 

In  the  centre  of  the  posterior  part 
of  the  globe  of  the  eye  the  retina 
presents  a  circular  spot,  which  is 
called  the  foramen  of  Soemmering  ;f 
it  is  surrounded  by  a  yellow  halo, 
the  limhus  luteus,  and  is  frequently 
obscured  by  an  elliptical  fold  of  the 
retina,  which,  from  its  constancy  of 
appearance,  has  been  regarded  as  a  normal  condition  of  the  mem- 

*  The  posterior  segment  of  the  transverse  section  of  the  globe  of  the  eye,  seen  from 
\vithin.  1.  The  divided  edge  of  the  three  tunics.  Tlie  membrane  covering  the  whole 
internal  surface  is  the  retina.  2.  The  entrance  of  the  optic  nerve  with  the  arteria  cen- 
tralis retinae  piercing  its  centre.  3,  3.  The  ramifications  of  the  arteria  centralis. 
4.  The  foramen  of  Soemmering,  in  the  centre  of  the  axis  of  the  eye;  the  shade  from 
the  sides  of  the  section  obscures  the  Jimbus  luteus  which  surrounds  it.  5.  A  fold  of 
the  retina,  which  generally  obscures  the  foramen  of  Soemmering  after  the  eye  has  been 
opened. 

t  Samuel  Thomas  Soemmering  is  celebrated  for  the  beautiful  and  accurate  plates 
which  accompany  his  works.  The  account  "  De  Foramine  Ccntrali  Retina?  Humanne, 
Limbo  Luteo  cincto,"  was  published  in  1779,  in  the  Commcntaliones  Soc.  Rfiff.  Scieiit. 
Goltincrcnsis. 


Fig.  138.* 


444  HUMOURS  OF  THE  EYE. 

brane.  The  term  foramen  is  misapplied  to  this  spot,  for  the  vascu- 
lar layer  and  the  membrani  Jacobi  are  continued  across  it ;  the  ner- 
vous substance  alone  appearing  to  be  deficient.  It  exists  only  in 
animals  having  the  axis  of  the  eyeballs  parallel  with  each  other,  as 
man,  quadrumana,  and  some  saurian  reptiles,  and  is  said  to  give 
passage  to  a  small  lymphatic  vessel. 

The  zonula  ciliaris  (zonula  of  Zinn)*  is  a  thin  vascular  layer 
which  connects  the  anterior  margin  of  the  retina  with  the  anterior 
surface  of  the  lens  near  to  its  circumference.  It  presents  upon  its 
surface  a  number  of  small  folds  corresponding  with  the  ciliary  pro- 
cesses, between  which  they  are  received.  These  processes  are 
arranged  in  the  form  of  rays  around  the  lens,  and  the  spaces  be- 
tween them  are  stained  by  the  pigmentum  nigrum  of  the  cihary 
processes.  They  derive  their  vessels  from  the  vascular  layer  of  the 
retina.  The  under  surface  of  the  zonula  is  in  contact  with  the 
hyaloid  membrane,  and  around  the  lens  forms  the  anterior  fluted 
wall  of  the  canal  of  Petit. 

The  connexion  between  these  folds  and  the  ciliary  processes  may 
be  very  easily  demonstrated  by  dividing  an  eye  transversely  into 
two  portions,  then  raising  the  anterior  half,  and  allowing  the  vitreous 
humour  to  separate  from  its  attachment  by  its  own  weight.  The 
folds  of  the  zonula  will  then  be  seen  to  be  drawn  out  from  between 
the  folds  of  the  ciliary  processes. 

Humours. — The  Aqueous  humour  is  situated  in  the  anterior  and 
posterior  chambers  of  the  eye  ;  it  is  a  weakly  albuminous  fluid,  hav- 
ing an  alkaline  reaction,  and  a  specific  gravity  very  little  greater 
than  distilled  water.  According  to  Petit,  it  scarcely  exceeds  four 
or  five  grains  in  weight. 

The  anterior  chamber  is  the  space  intervening  between  the  cornea 
in  front,  and  the  iris  and  pupil  behind. 

The  'posterior  chamber  is  the  narrow  space,  less  than  half  a  line 
in  depth,f  bounded  by  the  posterior  surface  of  the  iris  and  pupil  in 
front,  and  by  the  ciliary  processes,  zonula  ciHaris,  and  lens  behind. 

The  two  chambers  are  lined  by  a  thin  layer,  the  secreting  mem- 
brane of  the  aqueous  humour. 

The  Vitreous  humour  forms  the  principal  bulk  of  the  globe  of  the 
eye.  It  is  an  albuminous  fluid  resembling  the  aqueous  humour  en- 
closed in  a  delicate  membrane,  the  hyaloid,  which  sends  processes 
into  its  interior,  forming  cells  in  which  the  humour  is  retained.  A 
small  artery  may  sometimes  be  traced  through  the  centre  of  the 
vitreous  humour  to  the  capsule  of  the  lens ;  it  is  surrounded  by  a 
tubular  sheath  of  the  hyaloid  membrane.  This  vessel  is  easily  in- 
jected in  the  foetus. 

*  John  Gottfried  Zinn,  Professor  of  Anatomy  in  Gottingen ;  his  "  Descriptio  Anato- 
mica  Oculi  Hurnani,"  was  published  in  1755  ;  with  excellent  plates.  It  was  republished 
by  WrisbcrjT  in  1780. 

t  Winslow  and  Licutaud  thouglit  tiie  iris  to  be  in  contact  with  the  lens;  it  frequent- 
ly adheres  to  the  capsule  of  the  latter  in  iritis.  The  depth  of  the  posterior  chamber  is 
greater  in  old  than  in  young  persons. 


CRYSTALLINE  HUMOTJE STRUCTURE.  445 

The  Crystalline  humour  or  lens  is  situated  immediately  behind 
the  pupil,  and  is  surrounded  by  the  ciliary  processes,  which  slightly 
overlap  its  margin.  It  is  more  convex  on  the  posterior  than  on  the 
anterior  surface,  and  is  embedded  in  the  anterior  part  of  the  vitreous 
humour,  from  which  it  is  separated  by  the  hyaloid  membrane.  It 
is  invested  by  a  peculiarly  transparent  and  elastic  membrane,  the 
capsule  of  the  lens,  which  contains  a  small  quantity  of  fluid  called 
liquor  Morgagni*  and  is  retained  in  its  place  by  the  attachment  of 
the  zonula  ciliaris.  Dr.  Jacob  is  of  opinion  that  the  lens  is  connected 
to  its  capsule  by  means  of  cellular  tissue,  and  that  the  liquor  Mor- 
gagni is  the  result  of  a  cadaveric  change. 

The  Lens  consists  of  concentric  layers,  of  which  the  external  are 
soft,  the  next  firmer,  and  the  central  form  a  hardened  nucleus, 
These  layers  are  best  demonstrated  by  boiling,  or  by  immersion  in 
alcohol,  when  they  separate  easily  from  each  other.  Another  divi- 
sion of  the  lens  takes  place  at  the  same  time ;  it  splits  into  three  tri- 
angular segments,  which  have  the  sharp  edge  directed  towards  the 
centre,  and  the  base  towards  the  circumference.  The  concentric 
lamellae  are  composed  of  minute  parallel  fibres,  which  are  united 
with  each  other  by  means  of  scalloped  borders ;  the  convexity  on 
the  one  border  fitting  accurately  the  concave  scallop  upon  the  other. 

Immediately  around  the  circumference  of  the  lens  is  a  triangular 
canal,  the  canal  of  Petit,-f  about  a  line  and  a  half  in  breadth.  It  is 
bounded  in  front  by  the  flutings  of  the  zonula  ciliaris ;  behind  by  the 
hyaloid  membrane ;  and  within  by  the  border  of  the  lens. 

The  Vessels  of  the  globe  of  the  eye  are  the  long,  and  short,  and 
anterior  ciliary  arteries,  and  the  arteria  centralis  retinae.  The  long 
ciliary  arteries,  two  in  number,  pierce  the  posterior  part  of  the  scle- 
rotic, and  pass  forward  on  each  side,  between  that  membrane  and 
the  choroid,  to  the  ciliary  ligament,  where  they  divide  into  two 
branches,  which  are  distributed  to  the  iris.  The  short  ciliary  arteries 
pierce  the  posterior  part  of  the  sclerotic  coat,  and  are  distributed  to 
the  internal  layer  of  the  choroid  membrane.  The  anterior  ciliary 
are  branches  of  the  muscular  arteries.  They  enter  the  eye  through 
the  anterior  part  of  the  sclerotic,  and  are  distributed  to  the  iris.  It 
is  the  increased  number  of  these  arteries  in  iritis  that  forms  the 
peculiar  red  zone  around  the  circumference  of  the  cornea. 

The  arteria  centralis  retince  enters  the  optic  nerve  at  about  half 
an  inch  from  the  globe  of  the  eye,  and  passing  through  the  porus 
opticus  is  distributed  upon  the  inner  surface  of  the  retina,  forming 
its  vascular  layer ;  one  branch  pierces  the  centre  of  the  vitreous 
humour,  and  supphes  the  capsule  of  the  lens. 

The  JVerves  of  the  eyeball  are  the  optic,  two  ciliary  nerves  from 

*  John  Baptist  Morgagni  was  born  in  1682.  He  was  appointed  Professor  of  Medi- 
cine in  Bologna,  and  published  the  first  part  ©f  his  "Adversaria  Anatomica,"  in  1706. 
He  died  in  1771. 

t  John  Louis  Petit,  a  celebrated  French  surgeon :  he  published  several  surgical  and 
anatomical  Essays,  in  the  early  part  of  the  18th  century.     He  died  in  1750. 


446  APPE^CDAGES  OF  THE  EYE. 

the  nasal  branch  of  the  ophthalmic,  and  the  ciliary  nerves  from  the 
ciliary  ganglion. 

Observations. — The  sclerotic  is  a  tunic  of  protection,  and  the 
cornea  a  medium  for  the  transmission  of  light.  The  choroid  sup- 
ports the  vessels  destined  for  the  nourishment  of  the  eye,  and  by  its 
pigmentum  nigrum  absorbs  all  loose  and  scattered  rays  that  might 
confuse  the  image  impressed  upon  the  retina.  The  iris,  by  means 
of  its  powers  of  expansion  and  contraction,  regulates  the  quantity  of 
light  admitted  through  the  pupil.  If  the  iris  be  thin,  and  the  rays  of 
light  pass  through  its  substance,  they  are  immediately  absorbed  by 
the  uvea  ;  and  if  that  layer  be  insufficient,  they  are  taken  up  by  the 
black  pigment  of  the  ciliary  processes. 

In  Albinoes,  where  there  is  an  absence  of  pigmentum  nigrum,  the 
rays  of  light  traverse  the  iris  and  even  the  sclerotic,  and  so  over- 
whelm the  eye  with  light,  that  sight  is  destroyed,  except  in  the 
dimness  of  evening  or  at  night. 

In  the  manufacture  of  optical  instruments  care  is  taken  to  colour 
their  interior  black,  with  the  same  object,  the  absorption  of  scattered 
rays. 

The  transparent  lamellated  cornea  and  the  humours  of  the  eye 
have  for  their  office  the  refraction  of  the  rays  in  such  proportion  as 
to  direct  the  image  in  the  most  favourable  manner  upon  the  retina. 
Where  the  refracting  medium  is  too  great,  as  in  over  convexity  of 
the  cornea  and  lens,  the  image  falls  short  of  the  retina  (myopia, 
near-sightedness) ;  and  where  it  is  too  little  the  image  is  thrown 
beyond  the  nervous  membrane  (presbyopia,  far-sightedness). 

These  conditions  are  rectified  by  the  use  of  spectacles,  which 
provide  a  differently  refracting  medium  externally  to  the  eye,  and 
thereby  correct  the  transmission  of  light. 

APPENDAGES  OF  THE  EYE. 

The  Appendages  of  the  eye  {tutamina  oculi)  are  the  eyebrows, 
eyelids,  eyelashes,  conjunctiva,  caruncula  lachrymalis,  and  the 
lachrymal  apparatus. 

The  Eyebrov:s  {sitpercilia)  are  two  projecting  arches  of  integu- 
ment covered  with  short  thick  hairs,  which  form  the  upper  boundary 
of  the  orbits.  They  are  connected  beneath  with  the  orbiculares, 
occipito-frontales,  and  corrugatores  superciliorum  muscles;  their 
use  is  to  shade  the  eyes  from  a  too  vivid  light,  or  protect  them  from 
particles  of  dust  and  moisture  floating  over  the  forehead. 

The  Eyelids  {palpehrcs)  are  two  valvular  layers  placed  in  front  of 
the  eye,  serving  to  defend  it  from  injury  by  their  closure.  When 
drawn  open  they  leave  between  them  an  elliptical  space,  the  angles 
of  which  are  called  canthL  The  outer  canthus  is  formed  by  the 
meeting  of  the  two  lids  at  an  acute  angle.  The  inner  canthus  is 
prolonged  for  a  short  distance  inwards  towards  the  nose,  and  a 
triangular  space  is  left  between  the  lids  in  this  situation,  which  is 
called  the  lacus  lachrymalis.     At  the  commencement  of  the  lacus 


TARSI MEIBOMIAN  GLANDS.  447 

lachrymalis  upon  each  of  the  two  hds  is  a  small  angular  projection, 
the  lachrymal  papilla  or  tubercle  ;  and  at  the  apex  of  each  papilla  is 
a  small  orifice  (punctum  lachrymale),  the  commencement  of  the 
lachrymal  canal. 

The  eyeUds  have,  entering  into  their  structure,  integument,  orbicu- 
laris muscle,  tarsal  cartilages,  Meibomian  glands,  and  conjunctiva. 

The  tegumeniary  cellular  tissue  of  the  eyelids  is  remarkable  for 
its  looseness  and  for  the  entire  absence  of  adipose  substance.  It  is 
particularly  hable  to  serous  infiltration.  The  fibres  of  the  orbicu- 
laris muscle  covering  the  eyelids,  are  extremely  thin  and  pale. 

The  Tarsal  cartilages  are  tw^o  thin  lamellas  of  fibro-cartilage 
about  an  inch  in  length,  which  give  form  and  support  to  the  eyelids. 
The  superior  is  of  a  semilunar  form,  about  one-third  of  an  inch  in 
breadth  at  its  middle,  and  tapering  to  each  extremity.  Its  lower 
border  is  broad  and  flat,  its  upper  is  thin,  and  gives  attachment  to 
the  levator  palpebrte  and  to  the  fibrous  membrane  of  the  lids. 

The  Inferior  fibro-cartilage  is  an  elliptical  band,  narrower  than  the 
superior,  and  situated  in  the  substance  of  the  lower  lid.  Its  upper 
border  is  flat,  and  corresponds  with  the  flat  edge  of  the  upper  car- 
tilage. The  lower  is  held  in  its  place  by  the  fibrous  membrane. 
At  the  inner  canthus  the  tarsal  cartilages  terminate  at  the  com- 
mencement of  the  lachrymalis,  and  are  attached  to  the  margin  of 
the  orbit  by  the  tendo  oculi.  At  their  outer  extremity  they  termi- 
nate at  a  short  distance  from  the  angle  of  the  canthus,  and  are 
retained  in  their  position  by  means  of  a  decussation  of  the  fibrous 
structure  of  the  broad  tarsal  ligament,  called  the  external  palpebral 
ligament. 

The  Fibrous  membrane  of  the  lids  is  firmly  attached  to  the  perios- 
teum, around  the  margin  of  the  orbit,  by  its  circumference,  and  to 
the  tarsal  cartilages  by  its  central  margin.  It  is  thick  and  dense  on 
the  outer  half  of  the  orbit,  but  becomes  thin  to  its  inner  side.  Its 
use  is  to  retain  the  tarsal  cartilages  in  their  place,  and  give  support 
to  the  lids ;  hence  it  has  been  named  the  broad  tarsal  ligament. 

The  Meibomian  glands*  are  embedded  in  the  internal  surface  of 
the  cartilages,  and  are  very  distinctly  seen  on  examining  the  inner 
surface  of  the  Uds.  They  have  the  appearance  of  parallel  strings 
of  pearls,  about  thirty  in  number  in  the  upper  cartilage,  and  some- 
what fewer  in  the  lower  ;  they  open  by  minute  foramina  upon  the 
edges  of  the  lids.  They  correspond  in  length  with  the  breadth  of 
the  cartilage,  and  are  consequently  longer  in  the  upper  than  in  the 
lower  lid. 

Each  gland  consists  of  a  single  lengthened  follicle  or  tube,  into 
which  a  number  of  small  clustered  follicles  open  ;  the  latter  are  so 
numerous  as  almost  to  conceal  the  tube  by  which  the  secretion  is 
poured  out  upon  the  margin  of  the  lids.  They  are  figured,  after 
a  very  careful  examination,  in  Dr.  Quain's  "  Elements  of  Anatomy." 

*  Henry  Meibomius,  "de  Vasis  Palpebrarum  Novis,"  1666. 


^. 


448  LACHKYMAL  APPARATUS. 

Occasionally  an  arch  is  formed  between  two  of  them,  as  is  seen  in 
that  figure,  and  produces  a  very  graceful  appearance. 

The  edges  of  the  eyelids  are  furnished  with  a  triple  row  of  lono^ 
thick  hairs,  which  curve  upwards  from  the  upper  lid,  and  down- 
wards from  the  lower,  so  that  they  may  not  interlace  with  each 
other  in  the  closure  of  the  eyelids,  and  prove  an  impediment  to  the 
opening  of  the  eyes.  These  are  the  eyelashes  (cilia),  important 
organs  of  defence  to  the  sensitive  surface  of  so  deUcate  an  organ 
as  the  eye. 

The  Conjunctiva  is  the  mucous  membrane  of  the  eye.  It  covers 
the  whole  of  its  anterior  surface,  and  is  then  reflected  upon  the  lids 
so  as  to  form  their  internal  layer.  The  duplicatures  formed  between 
the  globe  of  the  eye  and  the  lids  are  called  the  superior  and  inferior 
'palpebral  sinuses,  of  which  the  former  is  much  deeper  than  the  in- 
ferior. Where  it  covers  the  cornea  the  conjunctiva  is  very  thin 
and  closely  adherent,  and  no  vessels  can  be  traced  into  it.  Upon 
the  sclerotica  it  is  thicker  and  less  adherent,  and  to  the  inner  sur- 
face of  the  lids  is  very  closely  connected,  and  is  exceedingly  vas- 
cular. It  is  continuous  with  the  general  gastro-pulmonary  mucous 
membrane,  and  sympathizes  in  its  aflections,  as  may  be  observed  in 
various  diseases.  From  the  surface  of  the  eye  it  may  be  traced 
through  the  lachrymal  gland  ;  along  the  edges  of  the  lids  it  is  con- 
tinuous with  the  mucous  hning  of  the  Meibomian  glands,  and  at  the 
inner  angle  of  the  eye  may  be  followed  through  the  lachrymal 
canals  into  the  lachrymal  sac,  and  thence  downwards  through  the 
nasal  duct  into  the  inferior  meatus  of  the  nose. 

This  membrane  is  coated  with  a  lamellated  epithelium  composed 
of  vesicles  and  flattened  scales,  with  central  nuclei. 

The  Caruncula  lachrymalis  is  the  small  reddish  body  which  occu- 
pies the  lacus  lachrymalis  at  the  inner  canthus  of  the  eye.  In 
health  it  presents  a  bright  pink  tint ;  in  sickness  it  loses  its  colour 
and  becomes  pale.  It  consists  of  an  assemblage  of  follicles  similar 
to  the  Meibomian  glands,  embedded  in  a  fibro-cartilaginous  tissue, 
and  is  the  source  of  the  whitish  secretion  which  so  constantly  forms 
at  the  inner  angle  of  the  eye.  It  is  covered  with  minute  hairs 
which  are  sometimes  so  long  as  to  be  distinctly  visible  to  the  naked 
eye. 

Immediately  to  the  outer  side  of  the  caruncula  is  a  slight  dupli- 
cature  of  the  conjunctiva,  called  plica  semilunaris,  which  contains 
a  minute  plate  of  cartilage,  and  is  the  rudiment  of  the  third  lid  of 
animals,  the  membrana  nictitans  of  birds. 

Vessels  and  nerves. — The  palpebral  are  supplied  internally  with 
arteries  from  the  ophthalmic,  and  externally  from  the  facial  and 
transverse  facial.  Their  nerves  are  branches  of  the  fifth  and  of  the 
facial. 

LACHRYMAL  APPARATUS. 

The  Lachrymal  apparatus  consists  of  the  lachrymal  gland  with 


LACHRYMAL  GLAND,  CANALS  AND  SAC.  449 

its  excretory  ducts ;  the  puncta  lachrymalia,  and  lachrymal  canals ; 
the  lachrymal  sac  and  nasal  duct. 

The  Lachrymal  gland  is  situated  at  the  upper  and  outer  angle  of 
the  orbit,  and  consists  of  two  portions,  orbital  and  palpebral.  The 
orbital  fortiori,  about  three  quarters  of  an  inch  in  length,  is  flattened 
and  oval  in  shape,  and  occupies  the  lachrymal  fossa  in  the  orbital 
plate  of  the  frontal  bone ;  being  in  contact  with  the  periosteum,  to 
which  it  is  closely  connected  by  its  upper  and  convex  surface ;  being 
in  relation  with  the  globe  of  the  eye,  and  with  the  superior  and  ex- 
ternal rectus  by  its  inferior  or  concave  surface ;  and  Vv'ith  the  broad 
tarsal  ligament  by  its  anterior  border.  By  its  posterior  border  it 
receives  its  vessels  and  nerves.  The  'palpebral  portion,  smaller  than 
the  preceding,  is  situated  in  the  upper  eyelid,  extending  downwards 
to  the  superior  margin  of  the  tarsal  cartilage.  It  is  continuous  with 
the  orbital  portion  above,  and  is  enclosed  in  an  investment  of  dense 
fibrous  membrane.  The  secretion  of  the  lachrymal  gland  is  con- 
veyed away  by  ten  or  twelve  small  ducts  which  run  for  a  short 
distance  beneath  the  conjunctiva,  and  open  upon  its  surface  by  a 
series  of  pores  about  one-twentieth  of  an  inch  apart,  situated  in  a 
curved  line  a  Uttle  above  the  upper  border  of  the  tarsal  cartilage. 

Lachrymal  canals. — The  lachrymal  canals  commence  at  the 
minute  openings,  puncta  lachrymalia,  seen  upon  the  lachrymal 
papillas  of  the  lids  at  the  outer  extremity  of  the  lacus  lachrymalis, 
and  proceed  inwards  to  the  lachrymal  sac,  where  ^they  terminate 
beneath  a  valvular  semilunar  fold  of  the  hning  membrane  of  the 
sac.  The  superior  duct  at  first  ascends,  and  then  turns  suddenly 
inwards  towards  the  sac,  forming  an  abrupt  angle.  The  inferior 
duct  forms  the  same  kind  of  angle,  by  descending  at  first,  and  then 
turning  abruptly  inwards.  They  are  dense  and  elastic  in  structure, 
and  remain  constantly  open,  so  that  they  act  like  capillary  tubes  in 
absorbing  the  tears  from  the  surface  of  the  eye.  The  two  fasciculi 
of  the  tensor  tarsi  muscle  are  inserted  into  these  ducts,  and  serve 
to  draw  them  inwards. 

The  Lachrymal  sac  is  the  upper  extremity  of  the  nasal  duct,  and 
is  scarcely  more  dilated  than  the  rest  of  the  canal.  It  is  lodged  in 
the  groove  of  the  lachrymal  bone,  and  is  often  distinguished  inter- 
nally from  the  nasal  duct  by  a  semilunar  or  circular  valve.  It  con- 
sists of  mucous  membrane,  but  is  covered  in  and  retained  in  its  place 
by  a  fibrous  expansion,  derived  from  the  tendon  of  the  orbicularis, 
which  is  inserted  into  the  ridge  on  the  lachrymal  bone :  it  is  also 
covered  by  the  tensor  tarsi  muscle,  which  arises  from  the  same  ridge, 
and  in  its  action  upon  the  lachrymal  canals  may  serve  to  compress 
the  lachrymal  sac. 

The  Nasal  duct  is  a  short  canal  about  three  quarters  of  an  inch 
in  length,  directed  downwards,  backwards,  and  a  little  outwards  to 
the  inferior  meatus  of  the  nose,  where  it  terminates  by  an  expanded 
orifice.  It  is  lined  by  mucous  membrane,  which  is  continuous  with 
the  conjunctiva  above,  and  with  the  pituitary  membrane  of  the  nose 

57 


450  OEGAN  OF  HEARIXO. 

below.     Obstruction  from  inflammation  and  suppuration  of  this  duct 
constitutes  the  disease  called  fistula  lachrymaHs. 

Vessels  and  nerves. — The  lachrymal  gland  is  supplied  with  blood 
by  the  lachrymal  branch  of  the  ophthalmic  artery,  and  \Yith  nerves 
by  the  lachrymal  branch  of  the  ophthalmic  and  orbital  branch  of 
the  superior  maxillary. 

THE  ORGAN  OF  HEARING. 

The  Ear  is  composed  of  three  parts.  1.  External  ear.  2.  Mid- 
dle ear,  or  tympanum.     3.  Internal  ear,  or  labyrinth. 

The  External  Ear  consists  of  two  portions,  the  pinna  and 
meatus;  the  former  representing  a  kind  of  funnel  which  collects  the 
vibrations  of  the  atmosphere,  called  sounds,  and  the  latter  a  tube 
which  conveys  the  vibrations  to  the  tympanum. 

The  Pinna  presents  a  number  of  folds  and  hollows  upon  its  sur- 
face, which  have  different  names  assigned  to  them.  Thus  the  ex- 
ternal folded  margin  is  called  the  helix  (=>^'i,  a  fold).  The  eleva- 
tion parallel  to  and  in  front  of  the  helix  is  called  antihelix  (avri,  op- 
posite.) The  pointed  process,  projecting  like  a  valve  over  the  open- 
ing of  the  ear  from  the.  face,  is  called  the  tragus  {r^ayog,  a  goat), 
probably  from  being  sometimes  covered  with  bristly  hair  Uke  that 
of  a  goat ;  and  a  tubercle  opposite  to  this  is  the  antitragus.  The 
lower  dependent  and  fleshy  portion  of  the  pinna  is  the  lohulus.  The 
space  between  the  helix  and  antihelix  is  named  \\\e  fossa  innominata. 
Another  depression  is  observed  at  the  upper  extremity  of  the  anti- 
helix, wliich  bifurcates  and  leaves  a  triangular  space  between  its 
branches  called  the  scaphoid  fossa  ;  and  the  large  central  space  to 
which  all  the  channels  converge  is  the  concha,  which  opens  directly 
into  the  ?neatus. 

The  pinna  is  composed  of  integument,  fihro-cartilage,  ligaments, 
and  muscles. 

The  Integument  is  thin,  and  closely  connected  with  the  fibro-car- 
lage. 

The  Fihro-cartilage  gives  form  to  the  pinna,  and  is  folded  so  as 
to  produce  the  various  convexities  and  grooves  which  have  been 
described  upon  its  surface.  The  helix  commences  in  the  concha, 
and  partially  divides  that  cavity  into  two  parts ;  on  its  anterior  bor- 
der is  a  tubercle  for  the  attachment  of  the  attraliens  aurem  muscle, 
and  a  little  above  this  a  small  vertical  fissure,  the  fissure  of  the 
helix.  The  termination  of  tlic  helix  and  antihelix  forms  a  length- 
ened process,  the  -processus  caudatus,  which  is  separated  from  the 
concha  by  an  extensive  fissure.  Upon  the  anterior  surface  of  the 
tragus  is  another  fissure,  the  fissure  of  the  tragus,  and  in  the  lobulus 
the  fibro-cartilage  is  wholly  deficient.  The  fibro-cartilage  of  the 
meatus,  at  the  upper  and  anterior  })art  of  the  cylinder,  is  divided 
from  the  concha  by  a  fissure  which  is  closed  in  the  entire  ear  by 
ligamentous  fibres ;  it  is  firmly  attaclicd  at  its  termination  to  the 
processus  auditorius. 


MUSCLES,  VESSELS,  AND  NERVES  OF  THE  EAR.  451 

The  Ligaments  of  the  external  ear  are  those  which  attach  the 
pinna  to  the  side  of  the  head,  viz.  the  anterior,  posterior,  and  liga- 
ment of  the  tragus ;  and  those  of  the  fibro-cartilage,  which  serve 
to  preserve  its  folds  and  connect  the  opposite  margins  of  the  fissures. 
The  latter  are  two  in  number,— the  ligament  between  the  concha 
and  the  processus  caudatus,  and  the  broad  ligament  which  extends 
from  the  upper  margin  of  the  fibro-cartilage  of  the  tragus  to  the 
helix,  and  completes  the  meatus. 

The  proper  Muscles  of  the  Pinna  are  the — 

Major  helicis. 

Minor  helicis, 

Tragicus, 

Antitragicus,  • 

Transversus  auriculae. 

The  Major  helicis  is  a  narrow  band  of  muscular  fibres  situated 
upon  the  anterior  border  of  the  helix,  just  above  the  tragus. 

The  Minor  helicis  is  placed  upon  the  posterior  border  of  the 
helix,  at  its  commencement  in  the  fossa  of  the  concha. 

The  Tragicus  is  a  thin  quadrilateral  layer  of  muscular  fibres, 
situated  upon  the  tragus. 

The  Antitragicus  arises  from  the  antitragus,  and  is  inserted  into 
the  posterior  extremity,  or  processes  caudatus  of  the  helix. 

The  Transversiis  auriculcB,  partly  tendinous  and  partly  muscular, 
extends  transversely  from  the  convexity  of  the  concha  to  that  of  the 
helix,  on  the  posterior  surface  of  the  pinna. 

These  muscles  are  rudimentary  in  the  human  ear,  and  deserve 
only  the  title  of  muscles  in  the  ears  of  animals.  Two  other  muscles 
are  described  by  Mr.  Tod,*  the  obliquus  auris  and  contractor  meatus, 
or  trago-helicus. 

The  Meatus  auditorius  is  a  canal,  partly  cartilaginous  and  partly 
osseous,  about  an  inch  in  length,  which  extends  inwards  and  a  little 
forwards  from  the  concha  to  the  tympanum.  It  is  narrower  in  the 
middle  than  at  each  extremity,  forms  an  oval  cyhnder,  the  long 
diameter  being  vertical,  and  is  slightly  curved  upon  itself,  the  con- 
cavity looking  downwards. 

It  is  lined  by  an  extremely  thin  pouch  of  cuticle,  which,  when 
withdrawn  after  maceration,  preserves  the  form  of  the  meatus. 
Some  slift'  short  hairs  are  also  found  in  its  interior,  which  stretch 
across  the  tube,  and  prevent  the  ingress  of  insects  and  dust.  Be- 
neath the  cuticle  are  a  number  of  small  ceruminous  follicles,  which 
secrete  the  wax  of  the  ear. 

Vessels  and  JVerves. — The  pinna  is  plentifully  supplied  with  arte- 
ries ;  by  the  anterior  auricular  from  the  temporal,  and  by  the  pos- 
terior nmicular  from  the  external  carotid. 

Its  Nerves  are  derived  from  the  auricular  branch  of  the  fifth,  and 
from  the  auricularis  magnus  of  the  cervical  plexus. 

*  "The  Anatomy  and  Physiology  of  the  Organ  of  Hearing,"  by  David  Tod,  1832. 


452  TVMPANUM CONTENTS. 

Tympanum. — The  tympanum  is  an  irregular  bony  cavity,  com- 
pressed from  without  inwards,  and  situated  within  the  petrous  bone. 
It  is  bounded  externally  by  the  meatus  and  membrana  tympani ;  zn- 
ierna/A/ by  its  inner  wall ;  and  in  its  circumference  by  the  petrous 
bone  and  mastoid  cells. 

The  Membrana  tympani  is  a  thin  and  semi-transparent  membrane 
of  an  ov^al  shape,  the  longer  diameter  being  nearly  vertical.  It  is 
inserted  into  a  groove  around  the  circumference  of  the  meatus  near 
to  its  termination,  and  is  placed  obliquely  across  the  area  of  that 
tube,  the  direction  of  the  obliquity  being  downwards  and  inwards. 
It  is  concave  towards  the  meatus,  and  convex  towards  the  tympa- 
num, and  is  composed  of  three  layers,  an  external  cuticular,  middle 
fibrous  and  muscular,  and  internal  mucous,  derived  from  the  mucous 
lining  of  the  tympanum. 

The  tympanum  contains  three  small  bones,  ossicula  auditus,  viz. 
the— 

Malleus, 

Incus, 

Stapes. 

The  Malleus  {hammer)  consists  of  a  head,  neck,  handle  {manu- 
brium), and  two  processes,  long  {processus  gracilis),  and  short  {pro- 
cessus brevis).  The  manubrium  is  connected  to  the  membrana 
tympani  by  its  whole  length  extending  to  below  the  central  point 
of  that  membrane.  It  lies  beneath  its  mucous  layer,  and  serves  as 
a  point  of  attachment  to  which  the  radiating  fibres  of  the  fibrous 
layer  converge.  The  long  process  descends  to  a  groove  near  to 
the  fissura  Glaseri,  and  gives  attachment  to  the  laxator  tympani 
muscle.  Into  the  short  process  is  inserted  the  tendon  of  the  tensor 
tympani,  and  the  head  of  the  bone  articulates  with  the  incus. 

The  Incus  {anvil)  is  named  from  an  imagined  resemblance  to  an 
anvil.  It  has  also  been  likened  to  a  bicuspid  tooth,  having  one  root 
longer,  and  widely  separated  from  the  other.  It  consists  of  two 
processes,  which  unite  nearly  at  right  angles,  and  at  their  junction 
form  a  flattened  body,  to  articulate  with  the  head  of  the  malleus. 
The  short  process  is  attached  to  the  margin  of  the  opening  of  the 
mastoid  cells  by  means  of  a  short  ligament ;  the  long  process 
descends  nearly  parallel  with  the  handle  of  the  malleus,  and  curves 
inwards,  near  to  its  termination.  At  its  extremity  is  a  small 
globular  projection,  the  as  orbiculare,  which  is  a  distinct  bone  in  the 
foetus,  but  becomes  anchylosed  to  the  long  process  of  the  incus  in 
the  adult;  this  process  articulates  with  the  head  of  the  stapes. 

The  Stapes  is  shaped  like  a  stirrup,  to  which  it  bears  a  close  re- 
semblance. Its  head  articulates  with  the  os  orbiculare,  and  the  two 
branches  are  connected  by  their  extremities  with  a  flat  oval-shaped 
plate,  representing  the  foot  of  the  stirrup.  The  foot  of  the  stirrup  is 
received  into  the  fenestra  ovalis,  to  the  margin  of  which  it  is  con- 
nected by  means  of  a  circular  ligament ;  it  is  in  contact,  by  its  sur- 


LIGAMENTS  OF  THE  TYMPANUM. 


453 


face,  with  the  membrana  vestibuli,  and  is  covered  in  by  the  mucous 
hning  of  the  tympanum.  The  neck  of  the  stapes  gives  attachment 
to  the  stapedius  muscle. 

Fig.  139.* 


The  ossicula  auditus  are  retained  in  their  position  and  moved 
upon  themselves  by  means  of  ligaments  and  muscles. 

The  Ligaments  are  three  in  number;  the  Ugament  of  the  head  of 
the  malleus,  which  is  attached  superiorly  to  the  upper  wall  of  the 
tympanum :  the  hgament  of  the  incus,  a  short  and  thick  band,  which 
serves  to  attach  the  extremity  of  the  short  process  of  that  bone  to 
the  margin  of  the  opening  of  the  mastoid  cells ;  and  the  circular 
ligament  which  connects  the  margin  of  the  foot  of  the  stapes  with 
the  circumference  of  the  fenestra  ovalis.  These  Hgaments  have 
been  described  as  muscles,  by  Mr.  Tod,  under  the  names  of  supe- 
rior capitis  mallei,  obliquus  incudis  externus  posterior,  and  mus- 
culus,  vel  structura  stapedius  inferior. 

*  A  diagram  of  the  ear.  p.  The  pinna,  t.  The  tympanum.  I.  The  labyrinth. 
1.  The  upper  part  of  the  helix.  2.  The  antihelix.  3.  Tlie  tragus.  4.  The  antitragus. 
5.  The  lobulus.  6.  The  concha.'^  7.  The  upper  part  of  the  fossa  innominata.  8. 
The  meatus.  9.  The  membrana  tympani,  divided  by  the  section.  10.  The  three 
little  bones,  crossing  the  area  of  tlie  tympanum,  malleus,  incus,  and  stapes  ;  the  foot  of 
the  stapes  blocks  up  the  fenestra  ovalis  upon  the  inner  wall  of  the  tympanum.  11. 
The  promontory.  12.  The  fenestra  rotunda;  the  dark  opening  above  the  ossicula 
leads  into  the  mastoid  cells.  13.  The  Eustachian  tube ;  the  little  canal  upon  this  tube 
contains  the  tensor  tympani  muscle  in  its  passage  to  the  tympanum.  14.  The  vesti- 
bule. 15.  The  three  semicircular  canals,  horizontal,  perpendicular,  and  oblique.  16. 
The  ampullfe  upon  the  perpendicular  and  horizontal  canals.  17.  The  cochlea.  18. 
A  depression  between  the  convexities  of  the  two  tubuli  which  communicate  witli  the 
tympanum  and  vestibule  ;  the  one  is  the  scala  tympani,  termmating  at  12  ;  the  other  is 
the  scala  vestibuli. 


454  MUSCLES  OF  THE  TYMPANU3I. 

.  The  Muscles  of  the  tympanum  are  four  in  number,  the — 

Tensor  tympani, 
Laxator  tympani, 
Laxator  tympani  minor, 
Stapedius. 

The  Tensor  tympani  (muscukis  internus  mallei)  arises  from  the 
spinous  process  of  the  sphenoid,  from  the  petrous  portion  of  the 
temporal  bone,  and  from  the  Eustachian  tube,  and  passes  forwards 
in  a  distinct  canal,  separated  from  the  tube  by  the  processus  coch- 
leariformis,  to  be  inserted  into  the  handle  of  the  malleus,  imme- 
diately below  the  commencement  of  the  processus  gracilis. 

The  Laxator  tympani  (musculus  externus  mallei)  arises  from  the 
spinous  process  of  the  sphenoid  bone,  and  passes  through  an  opening 
in  the  fissura  Glaseri,  to  be  inserted  into  the  long  process  of  the 
malleus. 

The  Laxator  tympani  minor  arises  from  the  upper  margin  of  the 
meatus,  and  is  inserted  into  the  handle  of  the  malleus,  near  to  the 
processus  brevis.  This  is  regarded  as  a  hgament  by  some  anato- 
mists. 

The  Stapedius  arises  from  the  interior  of  the  pyramid,  and  escapes 
from  its  summit  to  be  inserted  into  the  neck  of  the  stapes. 

The  openings  in  the  tympanum  are  ten  in  number,  five  large  and 
five  small;  they  are — 

Large  Openings.  Small  Openings. 

Meatus  auditorius.  Entrance  of  the  chorda  tympani, 

Fenestra  ovalis,  Exit  of  the  chorda  tympani, 

Fenestra  rotunda.  For  the  laxator  tympani, 

Mastoid  cells,  For  the  tensor  tympani, 

Eustachian  tube.  For  the  stapedius. 

The  opening  of  the  meatus  auditorius  has  been  previously  de- 
scribed. 

The  Fenestra  ovalis  (fenestra  vestibuli),  is  a  reniform  opening, 
situated  at  the  bottom  of  a  small  oval  fossa  (the  pelvis  ovalis),  in 
the  upper  part  of  the  inner  wall  of  the  tympanum,  directly  opposite 
the  meatus.  The  long  diameter  of  the  fenestra  is  directed  horizon- 
tally, and  its  convex  borders  upwards.  It  is  the  opening  of  com- 
munication between  the  tympanum  and  the  vestibule,  and  is  closed 
by  the  foot  of  the  stapes  and  by  the  lining  membranes  of  both 
cavities. 

The  Fenestra  rotunda  (fenestra  cochlea?)  is  somewhat  triangular 
in  its  form,  and  situated  in  the  inner  wall  of  the  tympanum,  below 
and  rather  posteriorly  to  the  fenestra  ovalis,  from  which  it  is  sepa- 
rated by  a  bony  elevation,  called  llic  promontory.  It  serves  to 
establish  a  communication  between  the  tympanum  and  the  cochlea. 


OPENINGS  OF  THE  TYMPANUM.  455 

In  the  fresh  subject  it  is  closed  by  a  proper  membrane,  as  well  as 
by  the  lining  of  both  cavities. 

The  Mastoid  cells  are  very  numerous,  and  occupy  the  whole  of 
the  interior  of  the  mastoid  process,  and  part  of  the  petrous  bone. 
They  communicate  by  a  large  irregular  opening  with  the  upper  and 
posterior  circumference  of  the  tympanum. 

The  Eustachian  tube  is  a  canal  of  communication  extending 
obliquely  between  the  pharynx  and  the  anterior  circumference  of 
the  tympanum.  In  structure  it  is  partly  fibro-cartilaginous  and 
partly  osseous,  is  broad  and  expanded  at  its  pharyngeal  extremity, 
and  narrow  and  compressed  at  the  tympanum. 

The  smaller  openings  serve  for  the  transmission  of  the  chorda  tym- 
pani  nerve,  and  three  of  the  muscles  of  the  tympanum. 

The  opening  by  which  the  chorda  tympani  e7iters  the  tympanum, 
is  near  the  root  of  the  pyramid,  at  about  the  middle  of  the  posterior 
wall. 

The  opening  of  exit  for  the  chorda  tympani  is  at  the  fissura  Glaseri 
in  the  anterior  wall  of  the  tympanum. 

The  opening  for  the  laxator  tympani  muscle  is  also  situated  in  the 
fissura  Glaseri,  in  the  anterior  wall  of  the  tympanum. 

The  opening  for  the  tensor  tympani  muscle  is  in  the  inner  wall, 
immediately  above  the  opening  of  the  Eustachian  tube. 

The  opening  for  the  stapedius  muscle  is  at  the  apex  of  a  conical 
bony  eminence,  called  the  pyramid,  which  is  situated  on  the  poste- 
rior wall  of  the  tympanum,  immediately  behind  the  fenestra  ovalis. 

Directly  above  the  fenestra  ovalis  is  a  rounded  ridge  formed  by 
the  projection  of  the  aquceductus  Fallopii. 

Beneath  the  fenestra  ovalis  and  separating  it  from  the  fenestra 
rotunda  is  the  promontory,  a  rounded  prominence  formed  by  the  pro- 
jection of  the  first  turn  of  the  cochlea.  It  is  channeled  upon  its  sur- 
face by  three  small  grooves,  which  lodge  the  three  tympanic  branches 
of  Jacobson's  nerve. 

The  Foramina  and  processes  of  the  tympanum  may  be  arranged, 
according  to  their  sit  nation,  into  four  groups. 

1.  In  the  External  ivall  is  the  meatus  auditorius,  closed  by  the 
memhrani  tympani. 

2.  In  the  Inner  wall,  from  above  downwards,  are  the — 

Opening  for  the  tensor  tympani. 

Ridge  of  the  aqu^ductus  Fallopii, 

Fenestra  ovahs. 

Promontory, 

Grooves  for  Jacobson's  nerve, 

Fenestra  rotunda. 

3.  In  the  Posterior  wall  are  the — 

Opening  of  the  mastoid  cells, 

Pyramid, 

Opening  for  the  stapedius, 

Apertura  chordce  (entrance). 


456  INTERNAL  EAK. 

4.  In  the  Anterior  wall  are  the — 

Eustachian  tube, 

Fissura  Glaseri, 

Opening  for  the  laxator  tympani, 

Apertura  chordae  (exit). 

The  tympanum  is  Hned  by  a  vascular  mucous  membrane,  which 
invests  the  ossicula  and  chorda  tympani,  and  forms  the  internal 
layer  of  the  membrani  tympani.  From  the  tympanum  it  is  reflected 
into  the  mastoid  cells,  which  it  lines  throughout,  and  passes  through 
the  Eustachian  tube  to  become  continuous  with  the  mucous  mem- 
brane of  the  pharynx. 

Vessels  and  Nerves. — The  Arteries  of  the  tympanum  are  derived 
from  the  internal  maxillary,  internal  carotid,  and  posterior  auricular. 

Its  Nerves  are — 1.  Minute  branches  from  the  facial,  which  are 
distributed  to  the  stapedius  muscle.  2.  The  chorda  tympani,  which 
leaves  the  facial  nerve  near  to  the  stylo-mastoid  foramen,  and  arches 
upwards  to  enter  the  tympanum  at  the  root  of  the  pyramid  ;  it  then 
passes  forwards  between  the  handle  of  the  malleus  and  long  process 
of  the  incus,  to  its  proper  opening  in  the  fissura  Glaseri.  3.  The 
tympanic  branches  of  Jacobson's  nerve,  which  are  distributed  to  the 
membranes  of  the  fenestra  oval  is  and  fenestra  rotunda,  and  to  the 
Eustachian  tube,  and  form  a  plexus  by  communicating  with  the 
carotid  plexus  and  otic  ganglion.  4.  A  filament  from  the  otic  gan- 
glion to  the  tensor  tympani  muscle. 

INTERNAL   EAR. 

The  Internal  ear  is  called  labyrinth,  from  the  complexity  of  its 
communications :  it  consists  of  a  membranous  and  an  osseous  por- 
tion. The  osseous  labyrinth  presents  a  series  of  cavities  which  are 
channeled  through  the  substance  of  the  petrous  bone,  and  is  situated 
between  the  cavity  of  the  tympanum  and  the  meatus  auditorius  in- 
ternus.     It  is  divisible  into  the — 

Vestibule, 

Semicircular  canals, 
Cochlea. 

The  Vestibule  is  a  small  three-cornered  cavity,  compressed  from 
without  inwards,  and  situated  immediately  within  the  inner  wall  of 
the  tympanum.  The  three  corners  which  are  named  ventricles  or 
cornua  arc  placed,  one  anteriorly,  one  superiorly,  and  one  poste- 
riorly. 

The  Anterior  ventricle  receives  the  oval  aperture  of  the  scala 
vestibuli ;  the  superior,  the  ampullary  o])enings  of  the  superior  and 
horizontal  semicircular  canals ;  the  posterior  ventricle  receives  the 
ampullary  opening  of  the  oblique  semicircular  canal,  the  common 
aperture  of  the  ol)lique  and  pcrpendiculnr  canals,  the  termination  of 


OPENINGS  OF  THE  VESTIBULE.  457 

the  horizontal  canal,  and  the  aperture  of  the  aquaeductiis  vestibuli. 
In  the  anterior  ventricle  is  a  small  depression,  which  corresponds 
with  the  posterior  segment  of  the  cnl  de  sac  of  the  meatus  audi- 
torius  internus  ;  it  is  called  the  fovea  hemispherica,  and  is  pierced 
by  a  cluster  of  small  openings,  the  macula  cribrosa.  In  the  sujyerior 
ventricle  of  the  vestibule  is  another  small  depression,  the  fovea 
eUiptica,  which  is  separated  from  the  fovea  hemispherica  by  a  pro- 
jecting crest,  the  eminentia  pyramid  alis.  The  latter  is  pierced  by 
numerous  minute  openings  for  the  passage  of  nervous  filaments. 
The  posterior  ventricle  presents  a  third  small  depression,  the  fovea 
sulciformis,  which  leads  upwards  to  the  ostium  aquseductus  vestibuli. 
The  internal  wall  of  the  vestibule  corresponds  with  the  bottom  of 
the  cul  de  sac  of  the  meatus  auditorius  internus,  and  is  pierced  by 
numerous  small  openings  for  the  transmission  of  nervous  filaments. 
In  the  external  or  tymfanic  wall  is  the  reniform  opening  of  the 
fenestra  ovalis  (fenestra  vestibuli),  the  margin  of  which  presents  a 
projecting  rim  towards  the  cavity  of  the  vestibule. 

The  openings  of  the  vestibule  may  be  arranged,  like  those  of  the 
tympanum,  into  large  and  small. 

The  Large  openings  are  seven  in  number,  viz.  the — 

Fenestra  ovalis, 

Scala  vestibuli. 

Five  openings  of  the  three  semicircular  canals. 

The  Small  openings  are  the — 

Aqua3ductus  vestibuli, 

Openings  for  small  arteries, 

Openings  for  branches  of  the  auditory  nerve. 

The  Fenestra  ovalis  has  already  been  described ;  it  is  the  opening 
into  the  tympanum. 

The  opening  of  the  scala  vestibuli  is  the  oval  termination  of  the 
vestibular  canal  of  the  cochlea. 

The  Jlquceductus  vestibuli  (canal  of  Cotunnius)  is  the  conmience- 
ment  of  the  small  canal  which  opens  under  the  osseous  scale  upon 
the  posterior  surface  of  the  petrous  bone.  It  gives  a  passage  to  a 
process  of  membrane  which  is  continuous  internally  with  the  lining 
membrane  of  the  vestibule,  and  externally  with  the  dura  mater,  and 
to  a  small  vein. 

The  Openings  for  the  arteries  and  nerves  are  situated  in  the  in- 
ternal wall  of  the  vestibule,  and  correspond  with  the  termination  of 
the  meatus  auditorius  internus. 

The  Semicircular  Canals  are  three  bony  passages  which  com- 
municate with  the  vestibule,  into  wiiich  they  open  by  both  extre- 
mities. Near  one  extremity  of  each  of  the  canals  is  a  remarkable 
dilatation  of  its  cavity,  which  is  called  the  ampulla  (sinus  ampullaceus). 
The  iwjjcy/or  or  perpendicular  canals  (canalis  scmicircularis  verticahs 


458  COCHLEA MODIOLUS, 

superior),  is  directed  transversely  across  tlie  petrous  portion  of  the 
temporal  hone,  forming  a  projection  upon  the  anterior  face  of  the 
.petrous  bone.  It  commences  by  means  of  an  ampulla  in  the  superior 
ventricle  of  the  vestibule,  and  terminates  posteriorly  by  joining  with 
the  oblique,  and  forming  a  common  canal,  which  opens  into  the 
upper  part  of  the  posterior  ventricle.  The  ?niddle  or  oblique  canal 
(canalis  semicircularis  verticalis  posterior),  corresponds  w^ith  the 
posterior  part  of  the  petrous  portion  of  the  temporal  bone ;  it  com- 
mences by  an  ampullary  dilatation  in  the  posterior  ventricle,  and 
curves  nearly  perpendicularly  upwards  to  terminate  in  the  common 
canal.  In  the  ampulla  of  this  canal  are  numerous  minute  openings 
for  nervous  filaments.  The  inferior  or  /lorizontal  canal  (canalis 
semicircularis  horizontalis),  is  directed  outwards  towards  the  base 
of  the  petrous  bone,  and  is  shorter  than  the  two  preceding.  It 
commences  by  an  ampullary  dilatation  in  the  superior  ventricle,  and 
terminates  in  the  posterior  ventricle. 

The  Cochlea  {snail  shell),  forms  the  anterior  portion  of  the  laby- 
rinth, corresponding  by  its  apex  with 
the  anterior  wall  of  the  petrous  bone, 
and  by  its  base  with  the  anterior 
depression  at  the  bottom  of  the  cul 
de  sac  of  the  meatus  auditorius  in- 
ternus.  It  consists  of  an  osseous 
and  gradually  tapering  canal,  about 
one  inch  and  a  half  in  length,  which 
makes  two  turns  and  a  half  spirally 
around  a  central  axis  called  the 
modiolus. 

The  central  axis  or  modiolus  is 
large  near  its  base  where  it  corre- 
sponds with  the  first  turn  of  the  cochlea,  and  diminishes  in  diameter 
towards  its  extremity.  At  its  base  it  is  pierced  by  numerous 
minute  openings  which  transmit  the  filaments  of  the  cochlear  nerve. 
These  openings  are  disposed  in  a  spiral  manner,  hence  they  have 
received  from  Cotunniusf  the  name  of  tractus  spirahs  foraminu- 

*  The  cochlea  divided  parallel  with  its  axis,  through  the  centre  of  the  modiolus. 
After  Breschet.  I.  The  modiolus.  2.  The  infundibulum  in  which  the  modiolus  ter- 
minates. 3,  3.  The  cochlear  nerve,  sending  its  filaments  through  the  centre  of  the 
modiolus.  4,  4.  The  scala  tympani  of  the  first  turn  of  the  cochlea.  5,  5.  The  scala 
vestibuli  of  the  first  turn.  6.  Section  of  the  lamina  spiralis,  its  zonula  ossea ;  one  of 
the  filaments  of  the  cochlear  nerve  is  seen  passing  between  the  two  layers  of  the  lamina 
spiralis  to  be  distributed  upon  the  membrane  which  invests  the  lamina.  7.  The  mem- 
branous portion  of  the  lamina  spiralis.  8.  Loops  formed  by  the  filaments  of  the 
cochlear  nerve.  'J,  9.  Scala  tympani  of  tlic  second  turn  of  the  cochlea.  10,  10,  Scala 
vestibuli  of  tlio  second  turn;  the  septum  between  the  two  is  the  lamina  spiralis.  11. 
The  scala  tympani  of  the  remaining  half  turn.  12.  The  remaining  half  turn  of  the 
scala  vestibuli ;  tlic  dome  placed  over  this  half  turn  is  the  cupola.  13.  The  lamina  of 
bone  which  forms  the  floor  of  the  scala  vestibuli  curving  spirally  round  to  constitute 
the  infundibulum  (2).  14.  The  helicotrema  through  which  a  bristle  is  passed  ;  its 
lower  extremity  issues  from  the  scala  tyrnpani  of  the  middle  turn  of  the  cochlea. 

t  Dominico  Cotunnius,  an  Italian  physician;  his  dissertation  "  De  Aqucfiduclibus 
Auris  Humanae  Interna;,"  was  published  in  Naples  in  1761. 


SCALA  TVMPANI  ET  VESTIBULI.  459 

lentus.  The  modiolus  is  every  where  traversed  in  the  direction 
of  its  length  by  minute  canals,  which  proceed  from  the  tractus 
spiralis  foraminulentus,  and  terminate  upon  the  sides  of  the  modiolus, 
by  opening  into  the  canal  of  the  cochlea  or  upon  the  surface  of  its 
lamina  spiralis.  The  central  canal  of  the  tractus  spiralis  foraminu- 
lentus is  larger  than  the  rest,  and  is  named  the  tubulus  centralis 
modioU  ;  it  is  continued  onwards  to  the  extremity  of  the  modiolus, 
and  transmits  a  nerve  and  a  small  artery,  the  arteria  centralis 
modioU. 

The  interior  of  the  canal  of  the  cochlea  is  partially  divided  into 
two  passages  (scalse)  by  means  of  a  thin  and  porous  lamina  of  bone 
(zonula  ossea  laminae  spiralis),  which  is  wound  spirally  around  the 
modiolus  in  the  direction  of  the  canal.  This  bony  septum  extends 
for  about  two-thirds  across  the  diameter  of  the  canal,  and  in  the 
fresh  subject  is  prolonged  to  the  opposite  wall  by  means  of  a  mem- 
branous layer,  so  as  to  constitute  a  complete  partition — the  lamina 
spiralis.  The  osseous  lamina  spiralis  consists  of  two  thin  lamellas 
of  bone,  between  which,  and  through  the  perforations  on  their  sur- 
faces, the  filaments  of  the  cochlear  nerve  reach  the  membrane  of 
the  cochlea.  At  the  apex  of  the  cochlea  the  lamina  spiralis  termi- 
nates in  a  pointed,  hook-shaped  process,  the  hamulus  laminae  spiralis. 
The  two  scales  of  the  cochlea  which  are  completely  separated 
throughout  their  length  in  the  living  ear,  communicate  superiorly 
over  the  hamulus  laminae  spiralis  by  means  of  an  opening  common 
to  both,  which  has  been  termed  by  Breschet  helico-trema  (sXi^,  sXIgcrc) 
volvere — T-^>5fia).  Inferiorly,  one  of  the  two  scalse,  the  scala  vestibuli, 
terminates  by  means  of  an  oval  aperture  in  the  anterior  ventricle 
of  the  vestibule  ;  while  the  other,  the  scala  tympani,  becomes  some- 
what expanded,  and  opens  into  the  tympanum  through  the  fenestra 
rotunda  (fenestra  cochleae).  Near  to  the  termination  of  the  scala 
tympani  is  the  small  opening  of  the  aquaeductus  cochlese. 

The  internal  surface  of  the  osseous  labyrinth  is  lined  by  a  f^bro- 
serous  membrane,  which  is  analogous  to  the  dura  mater  in  perform- 
ing the  office  of  a  periosteum  by  its  exterior,  whilst  it  fulfils  the 
purpose  of  a  serous  membrane  by  its  internal  layer,  secreting  a 
limpid  fluid,  the  aqua  labyrinthi  (liquor  Cotunnii),  and  sending  a 
reflection  inwards  upon  the  nerves  distributed  to  the  membranous 
labyrinth.  In  the  cochlea  the  membrane  of  the  labyrinth  invests 
the  two  surfaces  of  the  bony  lamina  spiralis,  and  being  continued 
from  its  border  across  the  diameter  of  the  canal  to  its  outer  wall, 
forms  the  membranous  lamina  spiralis  and  completes  the  separation 
between  the  scala  tympani  and  scala  vestibuh.  The  fenestra  ovahs 
and  fenestra  rotunda  are  closed  by  an  extension  of  this  membrane 
across  them,  assisted  by  the  membrane  of  the  tympanum  and  a 
proper  intermediate  layer.  Besides  lining  the  interior  of  the  osseous 
cavity  the  membrane  of  the  labyrinth  sends  two  delicate  processes 
along  the  aqueducts  of  the  vestibule  and  cochlea  to  the  internal  sur- 
face of  the  dura  mater  of  the  petrous  portion  of  the  temporal  bone, 
with  which  they  are  continuous.     These  processes  are  the  remains 


460 


MEMBRAXOUS  LABYRIX'TH. 


Fiff.  141  .t 


of  a  communication  originally  subsisting  between  the  dura  mater 

and  the  cavity  of  the  labyrinth.* 

The  Membranous  LxVbykinth  is  smaller  in  size,  but  a  perfect 
counterpart,  with  respect  to  form,  of  the 
vestibule  and  semicircular  canals.  It 
consists  of  a  small  elongated  sac,  sacculus 
communis  (utriculus  communis) ;  of  three 
semicircular  membranous  canals,  which 
correspond  with  the  osseous  canals,  and 
communicate  with  the  sacculus  com- 
munis ;  and  of  a  small  round  sac  (saccu- 
lus proprius),  which  occupies  the  anterior 
ventricle  of  the  vestibule,  and  lies  in  close 
contact  with  the  external  surface  of  the 
sacculus  communis. 

The  membranous  semicircular  canals 
are  two-thirds  smaller  in  diameter  than 
the  osseous  canals.  The  membranous 
labyrinth  is  retained  in  its  position  by 


*  Cotunnius  regarded  these  processes  as  tubular  caTials,  through  which  the  supera- 
bundant aqua  labyrintlii  might  be  expelled  into  the  cavity  of  the  cranium.  Mr.  Whar- 
ton Jones,  in  the  article  "  Organ  of  Hearing"  in  the  Cyclopa-dia  of  Anatomy  and 
Physiology,  also  describes  them  as  tubular  canals  which  terminate  beneath  the  dura 
mater  of  the  petrous  bone  in  a  small  dilated  pouch.  In  tlie  ear  of  a  man  deaf  and 
dumb  from  birth,  he  found  the  termination  of  the  aqueduct  of  the  vestibule  of  unusu- 
ally large  size  in  consequence  of  irregular  dcvelopement. 

t  The  labyrinth  of  the  lelt  ear,  laid  open  in  order  to  show  its  cavities  and  the  mem- 
branous labyrinth.  After  Breschct,  I.  The  cavity  of  the  vestibule,  opened  from  its 
anterior  aspect  in  order  to  show  the  three-cornered  form  of  its  interior,  and  the  mem- 
branous labyrinth  wliich  it  contains.  The  figure  rests  upon  the  common  saccule  of  the 
membranous  labyrinth, — the  sacculus  communis.  2.  The  ampulla  of  the  superior  or 
perpendicular  semicircular  canal,  receiving  a  nervous  fasciculus  from  the  superior 
i)ranch  of  the  vestibular  nerve.  3,  4.  Tiie  superior  or  perpendicular  canal  with  its  con- 
tained membranous  canal.  5.  The  ampulla  of  the  inferior  or  horizontal  semicircular 
canal,  receiving  a  nervous  fasciculus  from  the  superior  branch  of  the  vestibular  nerve, 
6.  The  termination  of  the  membranous  canal  of  the  horizontal  semicircular  canal  in 
the  sacculus  communis.  7.  The  ampulla  of  the  middle  or  oblique  semicircular  canal, 
receiving  a  nervous  fasciculus  from  the  inferior  brancli  of  the  vestibular  nerve.  8.  TJic 
oblique  semicircular  canal  witli  its  membranous  canal.  9.  The  common  canal,  result- 
ing from  the  union  of  the  pcrpcudicular  with  tlie  oblique  semicircular  canal.  10.  The 
membranous  common  canal  terminating  in  tiic  sacculus  communis.  11.  The  otoconite 
of  tlic  sacculus  communis  seen  through  the  membranous  parietcs  of  that  sac.  A  nervous 
fasciculus  from  the  inferior  branch  of  the  vestibular  nerve  is  seen  to  be  distributed  to 
the  sacculus  communis  near  to  the  otoconite.  The  extremity  of  the  sacculus  above 
the  otoconite  is  lodged  in  tlie  sujwrior  ventricle  of  the  vestibule,  and  that  below  in  tlic 
inferior  ventricle.  12.  The  sacculus  proprius  situated  in  the  anterior  ventiicle ;  its 
otoconite  is  seen  through  its  membranous  parietcs,  and  a  nervous  fasciculus  derived 
from  the  middle  branch  of  the  vestibular  nerve  is  distributed  to  it.  The  spaces  around 
the  membranous  labyrinth  are  occupied  by  the  aqua  labyrinthi.  13.  1'hc  first  turn  of 
the  cochlea;  the  figure  is  situated  in  the  scala  tym])ani.  14.  The  extremity  of  the 
scala,  tympani  corresponding  with  the  fenestra  rotunda.  15.  The  lamina  spiralis;  the 
figure  is  situated  in  tlie  scala  vestibuli.  1  (i.  The  opening  of  the  scala  vestibuli  into  the 
vestibule.  17.  The  second  turn  of  the  cocldca  ;  the  figure  is  jjlaced  upon  the  lamina 
spiralis,  and  tliereforc  in  the  scala  vestibuli,  the  scala  tympani  being  beneath  the  laniina. 

18.  The  remaining  half  turn  of  the  cochlea;  the  figure  is  jjlaccd  in  the  scala  tym])ani. 

19,  The  lamina  spiralis  terminating  in  a  falciform  extremity.  The  dark  sjiace  in- 
cluded within  the  fiilciform  ciu've  of  the  extremity  of  the  lamina  spiralis  is  tlie  heli- 
cotrcma.     20,  The  iufundibuhim. 


DISTEIBUTION  OF  THE  AUDITORY  NEKVE.  461 

means  of  the  numerous  nervous  filaments  which  are  distributed  to  it 
from  the  openings  in  the  inner  wall  of  the  vestibule,  and  is  separated 
from  the  lining  membrane  of  the  labyrinth  b}'  the  aqua  labyrinthi. 

The  structure  of  the  membranous  labyrinth  is  composed  of  four 
layers :  an  external  or  serous  layer,  derived  from  the  lining  mem- 
brane of  the  labyrinth ;  a  vascular  layer,  in  which  an  abundance  of 
minute  vessels  are  distributed ;  a  nervous  layer  formed  by  the  ex- 
pansion of  the  filaments  of  the  vestibular  nerve  and  of  an  internal 
and  serous  membrane,  by  which  the  limpid  fluid  which  fills  the 
membranous  labyrinth  is  secreted.  Some  small  patches  of  pigment 
have  been  observed  by  Mr.  Wharton  Jones  in  the  tissue  of  the  mem- 
branous labyrinth  of  man.     Among  animals  such  spots  are  constant. 

The  membranous  labyrinth  is  filled  in  the  interior  with  a  limpid 
fluid,  first  well  described  by  Scarpa,  and  thence  named  liquor 
Scarpas*  (endolymph,  vitreous  humour  of  the  ear,)  and  contains  two 
small  calcareous  masses  called  otoconites.  The  otoconites  {ovs,  u7og 
Mvtg,  the  ear-dust),  consist  of  an  assemblage  of  minute,  crystalline 
particles  of  carbonate  and  phosphate  of  lime,  held  together  by  animal 
substance,  and  probably  retained  in  form  by  a  reflection  of  the  lining 
membrane  of  the  membranous  labyrinth.  They  are  found  suspended 
in  the  liquor  Scarpa,  one  in  the  sacculus  communis,  and  the  other 
in  the  sacculus  proprius,  from  that  part  of  each  sac  with  which  the 
nerves  are  connected. 

The  Auditory  Nerve  divides  into  two  branches  at  the  bottom  of 
the  cul  de  sac  of  the  meatus  auditorius  internus ;  a  vestibular  nerve, 
and  a  cochlear  nerve.  The  vestibular  nerve,  the  most  posterior  of 
the  two,  divides  into  three  branches,  superior,  middle,  and  inferior. 
The  superior  vestibular  branch  gives  off  a  number  of  filaments 
which  pass  through  the  minute  openings  of  the  eminentia  pyramidahs, 
and  of  the  superior  ventricle  of  the  vestibule,  and  are  distributed  to 
the  sacculus  communis,  and  to  the  ampulte  of  the  perpendicular  and 
horizontal  semicircular  canals.  The  middle  vestibular  branch  sends 
off"  numerous  filaments  which  pass  through  the  openings  of  the 
macula  cribrosa  in  the  anterior  ventricle  of  the  vestibule,  and  are 
distributed  to  the  sacculus  proprius.  The  inferior  and  smallest 
branch  takes  its  course  backwards  to  the  posterior  wall  of  the  vesti- 
bule, and  gives  oft^  filaments  which  pierce  the  wall  of  the  ampullary 
dilatation  of  the  oblique  canal  to  be  distributed  upon  its  ampulla. 
According  to  Stiefensand  there  is  in  the  situation  of  the  point  of 
entrance  of  the  nervous  filaments  into  the  ampullre  a  deep  depression 
upon  the  exterior  of  the  membrane,  and  upon  the  interior  a  corre- 
sponding projection,  which  forms  a  kind  of  transverse  septum,  par- 
tially dividing  the  cavity  of  the  ampulla  into  two  chambers. 

Upon  entering  the  structure  of  the  sacculi  and  ampullae,  the  ner- 
vous filaments  radiate  in  all  directions,  anastomosing  with  each 

*  Antonio  Scarpa  is  celebrated  for  several  beautiful  sarjrical  and  anatomical  mono- 
graphs; as,  for  example,  his  work  on  "Aneurism,"  "Do  Audita  ct  Olfactu,"  «.Vc.  An 
account  of  the  aqua  labyrinthi  will  be  found  in  iiis  anatomical  observations  "De  Struc- 
ture Fcnestrar'  Rotunda',  ct  de  Tympano  Secundnrio." 


462  ORGAN  OF  TASTE. 

Other,  and  forming  interlacements  and  loops,  and  they  terminate 
upon  the  inner  surface  of  the  membrane  in  minute  papillae,  resem- 
bling those  of  the  retina. 

The  Cochlear  nerve  divides  into  numerous  filaments  M'hich  enter 
the  foramina  of  the  tractus  spiralis  foraminulentus  in  the  base  of  the 
cochlea,  and  passing  upwards  in  the  canals  of  the  modiolus  bend 
outwards  at  right  angles,  to  be  distributed  in  the  tissue  of  the  lamina 
spiralis.  The  central  portion  of  the  nerve  passes  through  the  tubulus 
centralis  of  the  modiolus,  and  supphes  the  apicial  portion  of  the 
lamina  spiralis.  In  the  lamina  spiralis  the  nervous  filaments  lying 
side  by  side  on  a  smooth  plane  form  numerous  anastomosing  loops, 
and  spread  out  ultimately  into  a  nervous  membrane.  According  to 
Treviranus  and  Gottsche  the  ultimate  terminations  of  the  filaments 
assuine  the  form  of  papillse. 

The  Arteries  of  the  labyrinth  are  derived  principally  from  the 
auditory  branch  of  the  superior  cerebellar  artery. 

ORGAN  OF  TASTE. 

The  Tongue  is  composed  of  muscular  fibres,  which  are  distributed 
in  layers  arranged  in  various  directions :  thus,  some  are  disposed 
hnghudinally;  others  transversely;  others,  again,  ohJiquehj  and 
vertically.  Between  the  muscular  fibres  is  a  considerable  quantity 
of  adipose  substance. 

The  tongue  is  connected  posteriorly  with  the  os  hyoides  by  mus- 
cular attachment,  and  to  the  epiglottis  by  mucous  membrane,  form- 
ing the  three  folds  which  are  called  frcena  epiglottidis.  On  either 
side  it  is  held  in  connexion  with  the  lower  jaw  by  mucous  mem- 
brane, and  in  front  a  fold  of  that  membrane  is  formed  beneath  its 
under  surface,  which  is  named /rcc7z?/77i  lingua. 

The  surface  of  the  tongue  is  covered  by  a  dense  layer  analogous 
to  the  corium  of  the  skin,  which  gives  support  to  the  papilla!.  A 
raphe  marks  the  middle  line  of  the  organ,  and  divides  it  into  sym- 
metrical halves. 

The  Papilloi  of  the  tongue  are  the — 

Papilla3  circumvallatse. 
Papillae  conicoe, 
Papillce  filiformcs, 
Papillae  fungiformes. 

The  PapillcB  circumvallata;  are  of  large  size,  and  from  fifteen  to 
twenty  in  number.*  They  are  situated  on  the  dorsum  of  the  tongue, 
near  to  its  root,  and  form  a  row  upon  each  side,  which  meets  its 
fellow  at  the  middle  line,  like  the  two  branches  of  the  letter  V. 
Each  papillcc  resembles  a  cone,  attached  by  its  apex  to  the  bottom 
of  a  cup-shaped  depression:  hence  they  are  also  named  papillae 

*  I  think  it  rare  to  sc;r  more  than  nino,  four  on  each  side  of  tlie  middle  one,  wliioh 
is  always  the  lar;fcpt. — (>. 


PAP1LL.E  OF  TONGUE.  463 

calycifarmes.     This  cup-shaped  cavity  forms  a  kind  of  fossa  around 
the  papilla,  whence  their  name  circumvaUaUe. 

At  the  meeting  of  the  two  rows  of  these  papillae  upon  the  middle 
of  the  root  of  the  tongue,  is  a  deep  mucous  follicle  called  foramen 
ccEcum. 

The  Papillce  coniccB  and  filiformes  cover  the  whole  surface  of  the 
tongue  in  front  of  the  circumvallatse,  but  are  most  abundant  near  its 
apex.  They  are  conical  and  filiform  in  shape,  and  have  their  points 
directed  backwards. 

The  PajjillcE  fungi  formes  are  irregularly  dispersed  over  the  dorsum 
of  the  tongue,  and  are  easily  recognised  amongst  the  other  papillse 
by  their  rounded  heads  and  larger  size.  A  number  of  these  papillse 
will  generally  be  observed  at  the  tip  of  the  tongue. 

Behind  the  papillse  circumvallatee,  at  the  root  of  the  tongue,  are  a 
number  of  mucous  glands,  which  open  upon  the  surface.  They  have 
been  improperly  described  as  papillse  by  some  authors. 

Vessels  and  JVerves. — The  tongue  is  abundantly  supplied  with 
blood  by  the  lingual  arteries. 

The  JVerves  are  three  in  number,  and  of  large  size: — 1.  The 
gustatory  branch  of  the  fifth,  which  is  distributed  to  the  papillee,  and 
is  the  nerve  of  common  sensation  and  of  taste.  2.  The  glosso-pha- 
ryngeal,  which  is  distributed  to  the  mucous  membrane,  follicles,  and 
glands  of  the  tongue,  is  a  nerve  of  sensation  and  motion ;  it  also 
serves  to  associate  the  tongue  with  the  pharynx  and  larynx.  Pa- 
nizza's  experiments,  tending  to  prove  that  this  is  the  true  nerve  of 
taste,  are  rendered  questionable  by  recent  experiments.  3.  The 
lingual,  which  is  the  motor  nerve  of  the  tongue,  and  is  distributed 
to  the  muscles. 

The  Mucous  membrane  which  invests  the  tongue,  is  continous  with 
the  cutis  along  the  margins  of  the  lips.  On  either  side  of  the  frsenum 
linguae  it  may  be  traced  through  the  sublingual  ducts  into  the  sub- 
lingual glands,  and  along  Wharton's*  ducts  into  the  sub-maxillary 
glands ;  from  the  sides  of  the  cheeks  it  passes  through  the  openings 
of  Stenon'sj  ducts  to  the  parotid  gland ;  in  the  fauces,  it  forms  the 
assemblage  of  folUcles  called  tonsils,  and  may  be  thence  traced 
downwards  into  the  larynx  and  pharynx,  where  it  is  continuous  with 
the  general  gastro-pulmonary  mucous  membrane. 

Beneath  the  mucous  membrane  of  the  mouth  are  a  number  of 
small  glandular  granules,  which  pour  forth  their  secretion  upon  the 
surface.  A  considerable  number  of  them  are  situated  within  the 
lips,  in  the  palate,  and  in  the  floor  of  the  mouth.  They  are  named 
from  the  position  which  they  may  chance  to  occupy,  labial,  pala- 
tine glands,  &C.J 

*  Thomas  Wharton,  an  English  physician,  devoted  considerable  attention  to  the  ana- 
tomy of  the  various  glands  :  his  work,  entitled  "  Adenographia,"  ttc^  was  publislied  in 
1656. 

t  Nicholas  Stenon,  a  Danish  anatomist:  he  was  made  professor  in  Copenhnffen  in 
1672.  '         ^ 

t  These  glands  are  salivary,  having  the  same  structure  as  the  parotid  and  secreting 
tlie  same  fluid. — G. 


464 


OKGAN  OF  TOUCH. 


ORGAN  OF  TOUCH. 

Th&. Skin  is  composed  of  three  layers,  viz.  the 

Cutis, 

Rete  mucosum. 

Cuticle. 

The  Cutis  (dermis),  or  true  skin,  covers  the  entire  surface  of  the 
body,  and  is  continuous  with  the  mucous  membrane  which  lines  its 
cavities.  It  consists  of  two  layers,  a  deep  one  called  corium,  and  a 
superficial  or  •papillary  layer. 

The  Corium  is  the  base  of  support  to  the  skin,  and  owes  its  den- 
sity of  structure  to  an  interlacement  of  fibrous  bands  which  form  a 
firm  and  elastic  web.  By  its  under  surface  it  is  connected  with  the 
common  superficial  fascia  of  the  body,  and  presents  a  number  of 
areolae,  in  which  are  lodged  small  masses  of  adipose  tissue. 

On  the  upper  surface  the  fibres  are  more  closely  aggregated, 
and  form  a  smooth  plane  for  the  support  of  the  papillary  layer. 

The  corium  differs  very  much 
Yig.  142*  in  thickness  in  different   parts   of 

the  body;  thus,  on  the  lips,  eye- 
lids, and  scrotum  it  is  extremely 
thin.  On  the  head,  back,  soles  of 
the  feet,  and  palms  of  the  hand  it 
is  very  thick ;  and  on  the  more 
exposed  parts  of  the  body  it  is 
much  thicker  than  on  those  which 
are  protected. 

The  Papillary  layer  is  soft,  and 
formed  by  minute  papillae  which 
cover  every  part  of  its  surface. 
On  the  body  generally,  the  papillae 
are  very  small  and  irregular  in 
their  distribution;  they  are  best 
seen  in  the  palm  of  the  hand  or 
sole  of  the  foot,  where  they  are 
disposed  in  hncar  ridges,  as  indi- 
cated by  the  markings  on  the 
cuticle.     The  ridges  of  papillae  in 


M-. 


*  Tlio  anatomy  of  tlic  skin.  1.  The  culiclo,  sliowinjr  tlio  oblique  lamina;  of  wliich  it 
Ih  c;oiii|)oscd  and  tliu  imbricated  disponition  of  tbo  ridircs  upon  its  surface.  3,  The  retc 
irmcosum.  3.  Two  of  the  (pi.idrilateral  pa])illary  masses,  such  as  arc  seen  in  the 
palm  of  the  hand  or  sole  of  the  foot;  tlioy  are  composed  of  minute  conical  papillrc.  4. 
The  deeper  Inyer  of  the  cutis,  the  corium.  5.  Adipose  vesicles;  showinnf  their  appear- 
ance beneath  tlie  microscope.  6.  A  perspiratory  fjland  with  its  spiral  duet,  such  as  is 
seen  in  tlie  palm  of  the  hand  or  sole  of  the  foot.  7.  Another  perspiratory  tfland  with  a 
straighter  duct,  such  as  is  seen  in  the  scalp.  8.  Two  hairs  from  the  sculp,  enclosed  in 
their  follicles;  their  relative  depth  in  the  skin  is  preserved.  9.  A  pair  of  sebaceous 
glands,  opening  by  short  ducts  into  tiie  Ibllicle  ol'tlie  hair. 


RETE  MUCOSUM,  465 

these  situations  are  separated  from  each  other  by  longitudinal  fur- 
rows, and  are  divided  by  transverse  furrows  into  small  quadrilateral 
rounded  masses.  These  quadrilateral  masses  are  each  composed 
of  a  considerable  number  of  minute  papillas,  which  are  conical  in 
form  and  variable  in  length,  one  or  two  of  the  papillse  in  each  mass 
being  generally  longer  than  the  rest.  In  the  middle  of  the  trans- 
verse furrow,  between  the  papillse,  is  the  opening  for  the  perspira- 
tory duct. 

The  papillae  beneath  the  nail  have  a  peculiar  form  and  arrange- 
ment. At  the  root  of  the  nail  they  are  numerous,  but  small  and 
very  vascular ;  opposite  to  the  part  of  the  nail  called  lunula,  they 
are  scarcely  raised  above  the  surface,  and  less  vascular ;  but  beyond 
this  point  they  form  lengthened  vascular  plicae,  which  afford  a  large 
surface  of  secretion.  These  lengthened  papilla  deposit  the  horny 
secretion  in  longitudinal  lamellae,  which  give  to  the  nail  the  ribbed 
appearance  which  it  presents  upon  its  surface. 

Vessels  and  JVerves. — The  papillae  are  abundantly  supplied  with 
vessels  and  nerves ;  the  former  to  enable  them 
to  perform  the  office  of  secretion  in  the  pro-  Fig.  143.* 

duction  of  the  cuticle,  the  latter  to  give  them 
the  sensibility  necessary  to  an  organ  of  touch. 

The  Rete  mucosum  is  the  soft  medium  which 
is  situated  between  the  papillary  surface  of 
the  cutis  and  cuticle ;  after  a  careful  macera- 
tion it  may  be  separated  as  a  distinct  layer, 
particularly  in  the  negro,  where  it  is  firmer 
than  in  the  European,  and  contains  the  colour- 
ing matter  of  the  skin. 

The  name  rete  mucosum,  given  to  it  by 
Malpighi,  conveys  a  very  inaccurate  notion 
of  its  structure ;  for  it  is  neither  a  network, 
nor  is  it  mucous.  It  is  thin  upon  the  general  surface  of  the  body ; 
but  is  thicker  in  the  palm  of  the  hand  and  sole  of  the  foot,  and  pre- 
sents a  close  correspondence  with  the  thickness  of  the  cuticle. 
Examined  with  the  microscope,  it  is  seen  to  be  moulded  accurately 
upon  the  papillae,  being  thick  in  the  spaces  between  these,  and  thin 

*  Anatomy  of  a  portion  of  skin  taken  from  the  palm  of  the  hand.  1,  1.  The  papil- 
lary layer,  in  which  the  longitudinal  furrows  (2)  marking  the  arrangements  of  the 
papillee  into  ridges  is  shown.  Each  ridge  is  moreover  divided  by  transverse  furrows 
(.3)  into  small  quadrangular  masses.  The  quadrangular  masses  consist  of  a  tuft  of 
minute  conical  papillae,  of  which  one  or  two  are  frequently  longer  and  larger  than  the 
rest.  In  this  figure  the  long  papillas  are  alone  seen,  the  rest  being  too  numerous  to 
introduce  into  a  wood-engraving.  4,  4.  The  rete  mucosum  raised  from  the  papillary 
layer  and  turned  back;  the  under  surface  of  this  stratum  presents  an  accurate  impres- 
sion of  the  papillary  layer ;  on  which  are  seen  longitudinal  ridges  corresponding  with 
the  longitudinal  furrows,  transverse  ridges  corresponding  with  the  transverse  furrows, 
and  quadrangular  depressions  corresponding  with  the  quadrangular  masses  of  papilla?. 
Moreover,  wherever  one  of  the  long  papillse  exists,  a  distinct  conical  sheath  will  be 
found  in  the  rete  mucosum.  5,  5.  Perspiratory  ducts  drawn  out  straight  by  the  sepa- 
ration of  the  rete  mucosum  from  the  papillary  layer ;  the  point  at  which  each  perspi- 
ratory duct  issues  from  the  papillary  layer,  and  pierces  the  rete  mucosum,  is  the  middle 
of  the  transverse  furrow  between  the  quadrangular  masses. 

59 


466  STHUCTURE  OF  THE  CUTICLE. 

over  their  convexities  ;  hence  arises  the  appearance  of  a  network. 
In  the  rete  mucosum  from  the  hand,  these  depressions  are  arranged 
in  a  Unear  series,  as  are  the  papillas ;  in  other  situations  they  are 
more  irregular,  but  correspond  aWays  with  the  distribution  of  the 
papillte. 

The  rete  mucosum  is  the  freshly  secreted  layer  of  cuticle,  and 
gradually  hardens  as  it  approaches  the  surface.  It  has  been  shown 
by  Henle  to  be  composed  of  minute  oval  vesicular  cells,  which  be- 
come converted  in  the  hardened  cuticle  into  flattened  scales,  each 
containing  a  central  nucleus.  The  dark  pigment  of  the  negro  exists 
in  the  form  of  small  granules  of  colouring  matter. 

The  cuticle  (epidermis,  scarf-skin)  is  the  horny  unorganized 
lamella  which  covers  and  protects  the  entire  surface  of  the  more 
dehcate  layers  of  the  skin.  In  situations  exposed  to  pressure,  as 
the  palm  of  the  hand  and  sole  of  the  foot,  it  is  very  thick ;  on  other 
parts  it  forms  only  a  thin  layer.  The  cuticle  is  marked  on  the  sur- 
face by  a  net-work  of  hnes :  these  are  more  numerous  and  larger 
near  to  joints,  where  they  form  deep  wrinkles  on  account  of  the 
inelastic  nature  of  its  structure.  Their  appearance  differs  in  different 
regions  of  the  body ;  but  every  where  depends  upon  the  same  cause, 
the  inelasticity  of  the  cuticle.  At  the  entrance  to  the  cavities  of  the 
body  it  is  continuous  with  the  epithelium  or  cuticular  covering  of 
the  mucous  membrane. 

The  cuticle,  in  minute  structure,  consists  of  several  successions 
of  laminaj  which  are  secreted  by  the  cutis ;  the  last  secreted  layer 
being  the  rete  mucosum.  The  rete  mucosum  is  composed  of  small 
round  masses  or  nuclei,  connected  together  by  a  glutinous  fluid 
containing  a  number  of  pigment  granules.  Each  nucleus  contains 
in  its  interior  a  minute  central  point,  the  nucleus-corpuscule,  and 
around  the  exterior  of  the  nucleus  a  vesicle  is  by  degrees  produced. 
The  middle  laminae  of  the  cuticle  are  composed  of  these  nucleated 
vesicles,  which  are  more  and  more  compressed  and  flattened  as  they 
are  observed  nearer  to  the  surface.  In  the  superficial  laminee  the 
vesicles  are  converted  into  thin  scales,  in  the  centre  of  which  the 
nucleus  with  the  nucleus-corpuscule  is  still  apparent.  The  laminae 
of  the  cuticle  arc  disposed  on  the  same  plane  with  the  surface  of 
the  skin  in  many  situations,  in  others  they  are  placed  obliquely  so 
as  to  project  by  their  free  extremities  upon  the  surface ;  in  the  palm 
of  the  hand  and  sole  of  the  foot  these  layers  correspond  with  the 
elevations  of  the  papillae,  and  present  an  imbricated  linear  surface. 
This  is  particularly  seen  on  the  points  of  the  fingers  where  the  rows 
of  papillas  have  a  circular  arrangement.  The  superficial  laminae 
of  the  cuticle  are  being  continually  thrown  off  by  exfoliation  or 
removed  by  abrasion,  to  give  place  to  the  deep  and  more  newly 
formed  layers. 

Upon  the  inner  surface  of  the  cuticle  a  number  of  depressions 
and  linear  furrows  are  seen,  corresponding  with  the  projections  of 
the  papillae.     A  number  of  conical  processes  are  also  observed  on 


NAILS HAIRS GLANDS.  467 

this  surface,  which  correspond  with  the  passage  of  hairs  through 
the  cuticle,  and  with  the  openings  of  the  perspiratory  ducts. 

The  Openings  in  the  cuticle  are  the  pores  or  openings  for  the  per- 
spiratory ducts,  the  openings  for  the  passage  of  the  hairs,  and  those 
of  the  sebaceous  follicles. 

APPENDAGES    TO    THE    SKIN. 

The  appendages  to  the  skin  are  the  nails,  hairs,  sebaceous  glands, 
and  perspiratory  glands  and  ducts. 

The  Kails  are  parts  of  the  cuticle  secreted  in  the  same  manner, 
composed  of  the  same  material,  but  disposed  in  a  peculiar  way  to 
serve  an  especial  purpose — the  protection  of  the  tactile  extremities 
of  the  fingers.  They  are  inserted  by  their  root  into  a  deep  groove 
(matrix)  of  the  skin,  and  are  firmly  attached  to  the  papillary  surface 
by  the  close  connexion  of  the  papillse  with  the  longitudinal  laminas. 
The  white  semilunar  segment  near  the  root  of  the  nail  is  called  the 
lunula.  The  cuticle  is  closely  connected  with  it  all  round,  and  in 
maceration  the  nail  comes  off  with  that  layer. 

The  Hairs  have  a  very  different  structure  and  arrangement  from 
that  of  the  nails :  they  are  inserted  for  a  considerable  depth  within 
the  integument,  and  terminate  in  conical  or  somewhat  bulbous  roots. 
Each  hair  is  enclosed  beneath  the  surface  by  a  vascular  secretory 
follicle,  which  regulates  its  form  during  growth. 

Hairs  are  very  rarely  completely  cylindrical ;  they  are  generally 
more  or  less  compressed,  and  somewhat  prismoid  in  form.  The 
transverse  section  is  reniform ;  in  texture  it  is  dense  and  homoge- 
neous towards  the  circumference,  and  porous  and  cellular  in  the 
centre  like  the  pith  of  a  plant. 

The  Sebaceous  glands  are  abundant  in  some  parts  of  the  skin,  as 
in  the  armpits,  the  nose,  &c.,  and  vary  in  complexity  of  structure 
from  a  simple  pouch-like  follicle  to  a  lobulated  gland.  At  the  ex- 
tremity of  the  nose  they  have  several  lobes ;  and  in  the  scalp  they 
are  lobulated  like  a  bunch  of  grapes,  and  terminate  in  the  follicles 
of  the  hairs  near  to  the  surface  of  the  skin.  They  secrete  an  oily 
fluid  which  is  poured  out  upon  the  surface  of  the  skin,  and  tends  to 
preserve  the  flexibility  of  the  cuticle. 

The  Perspiratory  ducts  are  minute  spiral  tubes  which  commence 
in  small  lobulated  glands,  situated  deeply  in  the  integument  beneath 
the  corium  and  among  the  adipose  vesicles.  They  are  easily  seen 
by  examining  a  thin  perpendicular  section  of  the  skin  from  the  palm 
of  the  hand,  with  a  lens  of  moderate  power.  Proceeding  from  the 
glands,  the  ducts  ascend  through  the  transverse  furrow,  between 
the  quadrilateral  masses  of  papilla  and  through  the  rete  mucosum 
to  terminate  by  open  pores  upon  the  surface  of  the  cuticle.  That 
portion  of  the  tube  which  is  situated  in  the  cuticle,  is  pretty  equally 
spiral ;  but  that  below  the  level  of  the  papillary  surface  is  very  irre- 
gularly twisted,  and  is  often  nearly  straight.  In  the  scalp  the  tubes 
are  serpentine,  or  but  slightly  curved. 


468  PORES  OF  THE  SKIN. 

A  good  view  of  the  perspiratory  ducts  passing  between  the  cutis 
and  cuticle,  may  be  obtained  by  peeling  off  the  cuticle  from  the 
palm  of  the  hand  in  a  decomposing  limb ;  or  by  scalding  a  small 
portion-  of  integument  and  then  separating  the  cuticle. 

The  Po7-es  are  best  observed  during  perspiration,  when  the  fluid 
is  seen  oozing  through  their  minute  openings.  In  the  hand  and  sole 
of  the  foot  they  are  easily  seen  by  the  naked  eye  without  this  assis- 
tance. They  are  disposed  at  regular  distances  along  the  ridges  of 
the  cuticle,  and  give  rise  to  the  appearance  of  lines  cutting  the  ridges 
transversely. 


CHAPTER   X. 


OF  THE  VISCERA. 


That  part  of  the  science  of  anatomy  which  treats  of  the  viscera 
is  named  splanchnology,  from  the  Greek  words  d'^fXay'/yov,  viscus, 
and  Xdyo?.  The  viscera  of  the  human  body  are  situated  in  the  three 
great  internal  cavities, — the  cranio-vertebral,  thorax,  and  abdomen. 
The  viscera  of  the  cranio-vertebral  cavity — the  brain  and  spinal 
cord,  with  the  principal  organs  of  sense — have  been  already  de- 
scribed, in  conjunction  with  the  nervous  system.  The  viscera  of  the 
chest  are — the  central  organ  of  circulation,  the  heart ;  the  organs 
of  respiration,  the  lungs  ;  and  the  thymus  gland.  The  abdominal 
viscera  admit  of  a  subdivision  into  those  which  properly  belong  to 
that  cavity,  viz.  the  alimentary  canal,  liver,  pancreas,  spleen,  kid- 
neys, and  supra-renal  capsules,  and  those  of  the  pelvis — the  bladder 
and  internal  organs  of  generation. 


THORAX. 

The  thorax  is  the  conical  cavity,  situated  at  the  upper  part  of  the 
trunk  of  the  body;  it  is  narrow  above  and  broad  below,  and  is 
bounded  in  front  by  the  sternum,  six  superior  costal  cartilages,  ribs, 
and  intercostal  muscles ;  laterally,  by  the  ribs  and  intercostal  mus- 
cles ;  and,  behind,  by  the  same  structures,  and  by  the  vertebral 
column,  as  low  down  as  the  upper  border  of  the  last  rib  and  the 
first  lumbar  vertebra ;  superiorly,  by  the  thoracic  fascia  and  first 
ribs ;  and,  inferiorly,  by  the  diaphragm. .  It  is  much  deeper  on  the 
posterior  than  on  the  anterior  wall,  in  consequence  of  the  obliquity 
of  the  diaphragm,  and  contains  the  heart,  enclosed  in  its  pericardium, 
with  the  great  vessels ;  the  lungs,  with  their  serous  covering^,  the 
pleurae  ;  the  cesophagus;  some  important  nerves  ;  and,  in  the  foetus, 
the  thymus  gland. 

THE  HEART. 

The  central  organ  of  circulation,  the  heart,  is  situated  between 
the  two  layers  of  pleura,  which  constitute  the  mediastinum,  and  is 
enclosed  in  a  proper  membrane,  the  pericardium. 


470 


PERICARDIUM. 


Pericardium. — The  pericardium  is  a  fibro-serous  membrane  like 

the  dm'a  mater,  and  resembles 
Fig.  144.*  that  membrane  in  deriving  its 

serous  layer  from  the  reflected 
serous  membrane  of  the  viscus 
which  it  encloses.  It  consists, 
therefore,  of  two  layers,  an  ex- 
ternal fibrous  and  an  internal 
serous.  The  fibrous  layer  is 
attached  above,  to  the  great 
vessels  at  the  root  of  the  heart, 
where  it  is  continuous  with  the 
thoracic  fascia ;  and  below  to 
the  tendinous  portion  of  the  dia- 
phragm. The  serous  membrane 
invests  the  heart  with  the  com- 
mencement of  its  great  vessels, 
and  is  then  reflected  upon  the  in- 
ternal surface  of  the  fibrous  layer. 
The  heart  is  placed  obliquely  in  the  chest,  the  base  being  directed 
upwards  and  backwards  towards  the  right  shoulder ;  the  apex  for- 
wards, and,  to  the  left,  points  to  the  space  between  the  fifth  and 
sixth  ribs,  at  about  two  or  three  inches  from  the  sternum.  Its  under 
side  is  flattened,  and  rests  upon  the  tendinous  portion  of  the  dia- 
phragm ;  its  upper  side  is  rounded  and  convex,  and  formed  princi- 
pally by  the  right  ventricle,  and  partly  by  the  left.  Surmounting 
the  ventricles  are  the  corresponding  auricles,  whose  auricular 
appendages  are  directed  forwards,  and  sUghtly  overlap  the  root  of 
the  pulmonary  artery.     The  pulmonary  artery  is  the  large  anterior 


*  The  anatomy  of  the  heart.  1.  The  right  auricle.  2.  The  entrance  of  the  supe- 
rior vena  cava.  3.  The  entrance  of  the  inferior  cava.  4.  The  opening  of  the  coronary 
vein,  half  closed  by  the  coronary  valve.  5,  The  Eustachian  valve.  6.  The  fossa  ovalis, 
surrounded  by  the  annulus  ovalis.  7.  The  tuberculum  Loweri.  8.  The  musculi  pec- 
tinati  in  the  appendix  auriculae.  9.  The  aurieulo-ventricular  opening.  10.  Thecavity 
of  the  right  ventricle.  11.  The  tricuspid  valve,  attached  by  the  chordoB  tcndinaB  to  the 
carnefE  columnae  (12).  13.  The  pulmonary  artery,  guarded  at  its  commencement  by 
three  semilunar  valves.  14.  The  right  pulmonary  artery,  passing  beneath  the  arch 
and  behind  the  ascending  aorta.  15.  The  left  pulmonary  artery,  crossing  in  front  of 
the  descending  aorta.  *  The  remains  of  the  ductus  arteriosus,  acting  as  a  ligament 
betw^cen  the  pulmonary  artery  and  arch  of  the  aorta.  The  arrows  mark  the  course  of 
the  venous  blood  through  the  right  side  of  the  heart.  Entering  the  auricle  by  the 
superior  and  inferior  cav£e,  it  passes  through  the  aurieulo-ventricular  opening  into  the 
ventricle,  and  thence  through  the  pulmonary  artery  to  the  lungs.  16.  The  left  auricle. 
17.  The  openings  of  the  four  pulmonnry  veins.  18.  The  auriculo-venti'icular  opening, 
19.  The  left  ventricle.  20.  The  mitral  valve,  attached  by  its  chordae  tendineaa  to  two 
large  columnae  carnete,  which  project  from  the  walls  of  the  ventricle.  21.  The  com- 
mencement and  course  of  the  ascending  aorta  behind  the  pulmonary  artery,  marked  by 
an  arrow.  The  entrance  of  the  vessel  is  guarded  by  three  semilunar  valves.  22.  The 
arch  of  the  aorta.  The  comparative  thickness  of  the  two  ventricles  is  shown  in  the 
diagram.  The  course  of  tlio  pure  blood  through  the  left  side  of  the  heart  is  marked  by 
arrows.  The  blood  is  brought  from  the  lungs  by  the  four  pulmonary  veins  into  the  left 
auricle,  and  passes  through  the  aurieulo-ventricular  opening  into  the  left  ventricle, 
whence  it  is  conveyed  by  the  aorta  to  every  part  of  the  body. 


OPENINGS  OF  THE  HEART.  471 

vessel  at  the  root  of  the  heart ;  it  crosses  obliquely  the  commence- 
ment of  the  aorta.  The  heart  consists  of  two  auricles  and  two 
ventricles,  which  are  respectively  named,  from  their  position,  right 
and  left.  The  right  is  the  venous  side  of  the  heart ;  it  receives  into 
its  auricle  venous  blood  from  every  part  of  the  body,  by  the  superior 
and  inferior  cava  and  coronary  vein.  From  the  auricle  the  blood 
passes  into  the  ventricle,  and  from  the  ventricle  through  the  pul- 
monary artery,  to  the  capillaries  of  the  lungs.  From  these  it  is 
returned  as  arterial  blood  to  the  left  auricle  ;  from  the  left  auricle 
it  passes  into  the  left  ventricle ;  and  from  the  left  ventricle  is  carried 
through  the  aorta,  to  be  distributed  to  every  part  of  the  body,  and 
again  returned  to  the  heart  by  the  veins.  This  constitutes  the  course 
of  the  adult  circulation. 

The  heart  is  best  studied  in  situ.  If,  however,  it  be  removed 
from  the  body,  it  should  be  placed  in  the  position  indicated  in  the 
above  description  of  its  situation.  A  transverse  incision  should  then 
be  made  along  the  ventricular  margin  of  the  right  auricle,  from  the 
appendix  to  its  right  border,  and  crossed  by  a  perpendicular  incision, 
carried  from  the  side  of  the  superior  to  the  inferior  cava.  The 
blood  must  then  be  removed.  Some  fine  specimens  of  white  fibrin 
are  frequently  found  with  the  coagula ;  occasionally  they  are 
yellow  and  gelatinous.  This  appearance  deceived  the.  older  anato- 
mists, who  called  these  substances  "  polypus  of  the  heart :"  they  are 
also  frequently  found  in  the  right  ventricle,  and  sometimes  in  the 
left  cavities. 

The  Right  Auricle  is  larger  than  the  left,  and  is  divided  into  a 
principal  cavity  or  sinus,  and  an  appendix  auriculae.  The  interior 
of  the  sinus  presents  for  examination  five  openings ;  two  valves ; 
two  relics  of  foetal  structure ;  and  two  peculiarities  in  the  proper 
structure  of  the  auricle.     They  may  be  thus  arranged : — 

Superior  cava, 
Inferior  cava, 

Openings <(  Coronary  vein. 

Foramina  Thebesii, 


Valves 


Auriculo- ventricular  opening. 

Eustachian  valve. 
Coronary  valve. 


n  7-      J-  ^  ^  1  .      s  \  Annulus  ovaUs, 

Relics  of  fcetal  structure     j  ^^^^^  ^^^j.^^ 

c,,      ^         r  si     n     •  1       \  Tuberculum  Loweri, 
Structure  of  the  Auricle      |  j^^^^^^j-  p^ctinati. 

The  Superior  cava  returns  the  blood  from  the  upper  half  of  the 
body,  and  opens  into  the  upper  and  front  part  of  the  auricle. 

The  Inferior  cava  returns  the  blood  from  the  lower  half  of  the 
body,  and  opens  into  the  lower  and  posterior  wall,  close  to  the  par- 
tition between  the  auricles  (septum  auriculorum).     The  direction  of 


472  VALVES OPENINGS. 

these  two  vessels  is  such,  that  a  stream  forced  through  the  superior 
cava  vi'-ould  be  directed  towards  the  auriculo-ventricular  opening. 
In  hke  manner,  a  stream  rushing  upwards  by  the  inferior  cava 
would  force  its  current  against  the  septum  auriculorum  ;  this  is  the 
proper  direction  of  the  two  currents  during  foetal  life. 

The  Coronary  vein  returns  the  venous  blood  from  the  substance 
of  the  heart ;  it  opens  into  the  auricle  between  the  inferior  cava  and 
the  auriculo-ventricular  opening,  under  cover  of  the  coronary  valve. 

The  Foramina  Tkebesii*  are  minute  pore-like  openings,  by  which 
the  venous  blood  exhales  directly  from  the  muscular  structure  of  the 
heart  into  the  auricle,  without  entering  the  venous  current.  These 
openings  are  also  found  in  the  left  auricle,  and  in  the  right  and  left 
ventricles. 

The  Auriculo-ventricular  opening  is  the  large  opening  of  com- 
munication between  the  auricle  and  ventricle. 

The  Eustac/iian-\  valve  is  a  part  of  the  apparatus  of  foetal  cir- 
culation, and  serves  to  direct  the  placental  blood  from  the  inferior 
cava,  through  the  foramen  ovale  into  the  left  auricle.  In  the  adult 
it  is  a  mere  vestige  and  imperfect,  though  sometimes  it  remains  of 
large  size.  It  is  formed  by  a  fold  of  the  lining  membrane  of  the 
auricle,  containing  some  muscular  fibres,  is  situated  between  the 
opening  of  the  inferior  cava  and  the  auriculo-ventricular  opening, 
and  is  generally  connected  with  the  coronary  valve. 

The  Coronary  valve  is  a  semilunar  fold  of  the  lining  membrane, 
stretching  across  the  mouth  of  the  coronary  vein,  and  preventing 
the  reflux  of  the  blood  in  the  vein  during  the  contraction  of  the 
auricle. 

The  Annulis  ovalis  is  situated  on  the  septum  auriculorum,  oppo- 
site the  termination  of  the  inferior  cava.  It  is  the  rounded  margin 
of  the  septum,  which  occupies  the  place  of  the  foramen  ovale  of 
the  foetus. 

The  Fossa  ovalis  is  an  oval  depression  corresponding  with  the 
foramen  ovale  in  the  foetus.  This  opening  is  closed  at  birth  by  a 
thin  valvular  layer,  which  is  continuous  with  the  left  margin  of  the 
annulis  and  is  frequently  imperfect  at  its  upper  part.  The  depres- 
sion or  fossa  in  the  right  auricle  results  from  this  arrangement. 
There  is  no  fossa  ovalis  in  the  left  auricle. 

The  Tuberculem  Loweri^  is  the  portion  of  auricle  intervening  be- 
tween the  openings  of  the  superior  and  inferior  cava.  Being  thicker 
than  the  walls  of  the  veins  it  forms  a  projection,  which  was  supposed 
by  Lower  to  direct  the  blood  from  the  superior  cava  into  the  auri- 
culo-ventricular opening. 

*  Adam  Christian  Thebesius.  His  discovery  of  the  openings  now  known  by  his 
name,  is  contained  in  his  "  Disscrtatio  Medica  de  Cireulo  Sanguinis  in  Corde,"  ]708. 

t  Bartholomew  Eustachius,  born  at  San  Severino,  in  Naples,  was  Professor  of  Medi- 
cine in  Rome,  where  he  died  in  1570.  He  was  one  of  the  founders  of  modern  anatomy, 
and  the  first  who  illustrated  his  works  with  good  engravings  on  copper. 

t  Richard  Lower,  M.D.  "  Tractatus  de  Corde ;  item  de  Motu  et  Colore  Sanguinis," 
1669.  His  dissections  were  made  upon  quadrupeds,  and  his  observations  relate  rather 
to  animals  than  to  man. 


EIGHT  VENTRICLE.  473 

The  Musculi  pecthiaii  are  small  muscular  columns  situated  in  the 
appendix  auriculae.  They  are  very  numerous,  and  are  arrancred 
parallel  w^ith  each  other;  hence  their  cognomen,  " peciinati,^^  like 
the  teeth  of  a  comb. 

The  RIGHT  VENTRICLE  is  triangular  and  three-sided  in  its  form. 
Its  anterior  side  is  convex,  and  forms  the  larger  proportion  of  the 
front  of  the  heart.  The  inferior  side  is  flat,  and  rests  upon  the  dia- 
phragm :  and  the  inner  side  corresponds  with  the  partition  between 
the  two  ventricles,  septum  ventriculorum. 

The  right  ventricle  is  to  be  laid  open  by  making  an  incision  par- 
allel with,  and  a  Httle  to  the  right  of,  the  middle  line,  from  the  pul- 
monary artery  in  front,  to  the  apex  of  the  heart,  and  thence  by  the 
side  of  the  middle  line  behind,  to  the  auriculo-ventricular  opening. 

It  contains,  to  be  examined,  two  openings,  the  auriculo-ventricular 
and  that  of  the  pulmonary  artery;  two  apparatus  of  valves,  the 
tricuspid  and  semilunar ;  and  a  muscular  and  tendinous  apparatus 
belonging  to  the  tricuspid  valves.     They  may  be  thus  arranged : — 

Auriculo-ventricular  opening, 
Opening  of  the  pulmonary  artery. 
Tricuspid  valves, 
Semilunar  valves. 
ChordsB  tendiness, 
Carnese  columnse. 

The  Auricido-ventricular  opening  is  surrounded  by  a  fibrous  ring, 
covered  by  the  lining  membrane  of  the  heart.  It  is  the  opening  of 
communication  between  the  right  auricle  and  ventricle. 

The  Opening  of  the  pulmonary  artery  is  situated  close  to  the  sep- 
tum ventriculorum,  on  the  left  side  of  the  right  ventricle,  and  upon 
the  anterior  aspect  of  the  heart. 

The  Tricuspid  valves  are  three  triangular  folds  of  the  lining  mem- 
brane, strengthened  by  a  thin  layer  of  fibrous  tissue.  They  are 
connected  by  their  base  around  the  auriculo-ventricular  opening ; 
and  by  their  sides  and  apices,  which  are  thickened,  they  give  at- 
tachment to  a  number  of  slender  tendinous  cords,  called  chordae 
tendinese.  The  chordce.  tendineas.  are  the  tendons  of  the  thick  mus- 
cular columns  {columnce  carnecB)  which  stand  out  from  the  walls  of 
the  ventricle,  and  serve  as  muscles  to  the  valves.  A  number  of  these 
tendinous  cords  converge  to  a  single  muscular  attachment.  The 
tricuspid  valves  prevent  the  regurgitation  of  blood  into  the  auricle 
during  the  contraction  of  the  ventricle,  and  they  are  prevented  from 
being  themselves  driven  back,  by  the  chordae  tendinae  and  their 
muscular  attachments. 

This  connexion  of  the  muscular  columns  of  the  heart  to  the  valves 
has  caused  their  division  into  active  and  passive.  The  active  valves 
are  the  tricuspid  and  mitral ;  the  passive  the  mere  folds  of  lining 
membrane,  viz.  the  semilunar.  Eustachian,  and  coronaiy- 

Mr.  T.  W.  King,  of  Guy's  Hospital,  has  made  the  tricuspid 

60 


474  COLUMN-E  CARNEY. 

valves  a  subject  of  special  investigation,  and  has  recorded  his  obser- 
vations in  a  very  interesting  paper*  in  the  Guy's  Hospital  Reports. 
The  valves  consist,  according  to  Mr.  King,  of  curtains,  cords,  and 
columns.  The  anterior  valve  or  curtain  is  the  largest,  and  is  so 
placed  as  to  prevent  the  filling  of  the  pulmonary  artery  during  the 
distention  of  the  ventricle.  The  7'ig/it  valve  or  curtain  is  of  smaller 
size,  and  is  situated  upon  the  right  side  of  the  auriculo-ventricular 
opening.  The  third  valve,  or  "fixed  curtain"  is  connected  by  its 
cords  to  the  septum  ventriculorum.  The  cords  (chordae  tendinese) 
of  the  anterior  curtain  are  attached,  principally,  to  a  long  column 
(columna  carnea),  which  is  connected  with  the  "  right  or  thin  and 
yielding  ivall  of  the  ventricle."  From  the  lower  part  of  this  column 
a  transverse  muscular  band,  the  "  loJig  moderator  hand^''  is  stretched 
to  the  septum  ventriculorum  or  "  solid  walV  of  the  ventricle.  The 
right  curtain  is  connected,  by  means  of  its  cords,  partly  with  the 
long  column,  and  partly  with  its  own  proper  column,  the  second 
column,  which  is  also  attached  to  the  "  yielding  wall"  of  the  ven- 
tricle. A  third  and  smaller  column  is  generally' connected  with  the 
right  curtain.  The  "  fixed  curtain"  is  named  from  its  attachment  to 
the  "  solid  wall"  of  the  ventricle,  by  means  of  cords  only,  without 
fleshy  columns. 

From  this  remarkable  arrangement  of  the  valves  it  follows,  that 
if  the  right  ventricle  be  over  distended,  the  thin  or  "  yielding  icall" 
will  give  way,  and  carry  with  it  the  columns  of  the  anterior  and 
right  valves.  The  cords  connected  with  these  columns  will  draw 
down  the  edges  of  the  corresponding  valves,  and  produce  an  open- 
ing between  the  curtains,  through  which  the  superabundant  blood 
may  escape  into  the  auricle,  and  the  ventricle  be  relieved  from 
over-pressure.  This  beautiful  mechanism  is  therefore  adapted,  to 
fulfil  the  "  function  of  a  safety  valve" 

The  ColumncB  carneae  (fleshy  columns)  is  a  name  expressive  of 
the  appearance  of  the  internal  walls  of  the  ventricles,  which  seem 
formed  of  muscular  columns  interlacing  in  almost  every  direction. 
They  are  divided  into  three  sets,  according  to  the  manner  of  their 
connexion.  1.  The  greater  number  are  attached  by  the  whole  of 
one  side,  and  merely  form  convexities  into  the  cavity  of  the  ven- 
tricle. 2.  Others  are  connected  by  both  extremities,  being  free  in 
the  middle.  3.  A  few  (columnar  papillares)  are  attached  by  one 
extremity  to  the  walls  of  the  heart,  and  by  the  other  give  insertion 
to  the  chordae  tendinese. 

The  Semilunar  valves,  three  in  number,  are  situated  around  the 
commencement  of  the  pulmonary  artery,  being  formed  by  a  folding 
of  its  lining  membrane,  strengthened  by  a  thin  layer  of  fibrous  tissue. 
They  are  attached  by  their  convex  borders,  and  free  by  the  con- 
cave which  are  directed  upwards  in  the  course  of  the  vessel,  so  that, 
during  the  current  of  the  blood  along  the  artery  they  are  pressed 
against  the  sides  of  the  cylinder;  but  if  any  attempt  at  regurgitation 

*  "Essay  on  the  Safety  Valve  Function  in  the  Right  Ventricle  of  the  Human  Heart," 
by  T.  W.  King.     Guy's  Hospital  Reports,  vol.  ii. 


LEFT  AURICLE  AA'D  VENTRICLE.  475 

ensue  they  are  immediately  expanded,  and  effectually  close  the 
entrance  of  the  tube.  The  margins  of  the  valves  are  thicker  than 
the  rest  of  their  extent,  and  each  valve  presents  in  the  centre  of  this 
margin  a  small  fibro-cartilaginous  tubercle,  called  corpus  Arantii,* 
which  locks  in  with  the  two  others  during  the  closure  of  the  valves, 
and  secures  the  triangular  space  that  would  otherwise  be  left  by  the 
approximation  of  three  semilunar  folds. 

Between  the  semilunar  valves  and  the  cylinder  of  the  artery  are 
three  pouches,  called  the  pulmonary  sinuses.  Similar  sinuses  are 
situated  behind  the  valves  at  the  commencement  of  the  aorta,  and 
are  much  larger  and  more  capacious  than  those  of  the  pulmonary 
artery. 

The  Pulmonary  artery  commences  by  a  scalloped  border,  corre- 
sponding with  the  three  valves  which  are  attached  along  its  edge. 
It  is  connected  to  the  ventricle  by  muscular  fibres,  and  by  the  lining 
membrane  of  the  heart. 

The  Left  Auricle  is  somewhat  smaller  than  the  right;  of  a 
cuboid  form,  and  situated  more  posteriorly.  The  appendix  auriculce 
is  constricted  at  its  junction  with  the  auricle,  and  has  an  arborescent 
appearance ;  it  is  directed  forwards  towards  the  root  of  the  pul- 
monary artery,  to  which  the  auriculae  of  both  sides  appear  to  con- 
verge. 

The  left  auricle  is  to  be  laid  open  by  a  -J-  shaped  incision,  the 
horizontal  section  being  made  along  the  border  which  is  attached  to 
the  base  of  the  ventricle. 

It  presents  for  examination  five  openings,  and  the  muscular  struc- 
ture of  the  appendix ;  these  are, — 

Four  pulmonary  veins. 
Auric ulo-ventricular  opening, 
Musculi  pectinati. 

The  Pulmonary  veins,  two  from  the  right  and  two  from  the  left 
lung,  open  into  the  corresponding  sides  of  the  auricle.  The  two  left 
pulmonary  veins  terminate  frequently  by  a  common  opening. 

The  Auricula-ventricular  opening  is  the  aperture  of  communica- 
tion between  the  auricle  and  ventricle. 

The  Musculi  pectinati  are  fewer  in  number  than  in  the  right 
auricle,  and  are  situated  only  in  the  appendix  auriculas. 

Left  Ventricle. — The  left  ventricle  is  to  be  opened,  by  making 
an  incision  a  little  to  the  left  of  the  septum  ventriculorum,  and  con- 
tinuing it  around  the  apex  of  the  heart,  to  the  auriculo-ventricular 
opening  behind. 

The  left  ventricle  is  conical,  both  in  external  figure  and  in  the 
form  of  its  internal  cavity.  It  forms  the  apex  of  the  heart,  by  pre- 
jecting  beyond  the  right  ventricle,  while  the  latter  has  the  advantage 

*  Julius  Caesar  Arantius,  Professor  of  Medicine  in  Bologna.  He  was  a  disciple  of 
Vesalius,  one  of  tlie  founders  of  modern  anatum)'.  His  treatise  "  De  Humani  Fcetu," 
was  published  at  Rome,  in  1564. 


476  STRUCTURE  OF  THE  HEART, 

in  length  towards  the  base.     Its  walls  are  about  seven  lines  in  thick- 
ness, those  of  the  right  ventricle  being  about  two  lines  and  a  half. 

It  presents  for  examination,  in  its  interior,  two  openings,  two 
valves,  and  the  tendinous  cords  and  muscular  columns ;  they  may 
be  thus  arranged  : — 

Auriculo- ventricular  opening, 
Aortic  opening. 

Mitral  valves, 
Semilunar  valves. 

Chordse  tendineae, 
Columnse  carnecs. 

The  Auriculo-ventricular  opening  is  a  dense  fibrous  ring,  covered 
by  the  Uning  membrane  of  the  heart,  but  smaller  in  size  than  that  of 
the  right  side. 

The  Mitral  valves  are  attached  around  the  auriculo-ventricular 
opening,  as  are  the  tricuspid  in  the  right  ventricle.  They  are  thicker 
than  the  tricuspid,  and  consist  of  only  two  segments,  of  which  the 
larger  is  placed  between  the  auriculo-ventricular  opening  and  the 
commencement  of  the  aorta,  and  acts  the  part  of  a  valve  to  that 
foramen,  during  the  filling  of  the  ventricle.  The  difference  in  size 
of  the  two  valves,  both  being  triangular,  and  the  space  between 
them,  has  given  rise  to  the  idea  of  a  "  bishop's  mitre"  after  which 
they  are  named.  These  valves,  like  the  tricuspid,  are  furnished 
with  an  apparatus  of  tendinous  cords,  chordcB  tendinecE,  which  are 
attached  to  two  very  large  columnce  carnece. 

The  ColumncB  carnece,  admit  of  the  same  arrangement  into  three 
kinds,  as  on  the  right  side.  Those  which  are  free  by  one  extremity, 
the  columnse  papillares,  are  only  two  in  number,  and  much  larger 
than  those  on  the  opposite  side. 

The  Semilunar  valves  are  placed  around  the  commencement  of 
the  aorta,  like  those  of  the  pulmonary  artery ;  they  are  similar  in 
structure,  and  are  attached  to  the  scalloped  border  by  which  the 
aorta  is  connected  with  the  ventricle.  The  tubercle  in  the  centre 
of  each  fold  is  larger  than  those  in  the  pulmonary  valves,  and  it  was 
these  that  Arantius  particularly  described ;  but  the  term  "  corpora 
Arantii"  is  now  applied  indiscriminately  to  both.  The  fossae  between 
the  semilunar  valves  and  the  cylinder  of  the  artery  are  much  larger 
than  those  of  the  pulmonary  artery;  they  are  called  the  "sinus 
aorticiJ'* 

STRUCTURE  OF  THE  HEART. 

The  arrangement  of  the  fibres  of  the  heart  has  been  made  the 
subject  of  careful  and  accurate  investigation  by  Mr.  Searle,  to 
whose  excellent  article,  "  Fibres  of  the  Heart,"  in  the  Cyclopaedia 
of  Anatomy  and  Physiology,  I  am  indebted  for  the  following  sum- 
mary of  their  distribution  : — 


FIBRES  OF  THE  VENTRICLES.  477 

For  the  sake  of  clearness  of  description  the  fibres  of  the  ventri- 
cles have  been  divided  into  three  layers, — superficial,  middle,  and 
internal — all  of  which  are  disposed  in  a  spiral  direction  around  the 
cavities  of  the  ventricles.  The  mode  of  formation  of  these  three 
layers  w^ill  be  best  understood  by  adopting  the  plan  pursued  by  Mr. 
Searle  in  tracing  the  course  of  the  fibres  from  the  centre  of  the 
heart  towards  its  periphery. 

The  left  surface  of  the  septum  ventriculorum  is  formed  by  a 
broad  and  thick  layer  of  fibres,  which  proceed  backwards  in  a  spiral 
direction  around  the  posterior  aspect  of  the  left  ventricle,  and 
become  augmented  on  the  left  side  of  that  ventricle,  by  other  fibres 
derived  from  the  bases  of  the  two  columnse  papillares.  The  bi'oad 
and  thick  band  formed  by  the  fibres  from  these  two  sources,  curves 
around  the  apex  and  lower  third  of  the  left  ventricle,  to  the  anterior 
border  of  the  septum,  where  it  divides  into  two  bands, — a  short  or 
apicial  band,  and  a  long  or  basial  band. 

The  Short  or  apicial  band  is  increased  in  thickness  at  this  point 
by  receiving  a  layer  of  fibres  (derived  from  the  root  of  the  aorta 
and  carnese  columnae)  upon  its  internal  surface,  from  the  right  sur- 
face of  the  septum  ventriculorum  ;  it  is  then  continued  onwards  in 
a  spiral  direction  from  left  to  right,  around  the  lower  third  of  the 
anterior  surface,  and  the  middle  third  of  the  posterior  surface  of 
the  right  ventricle  to  the  posterior  border  of  the  septum.  From  the 
latter  point  the  short  band  is  prolonged  around  the  posterior  and 
outer  border  of  the  left  ventricle  to  the  anterior  surface  of  the  base 
of  that  ventricle,  and  is  inserted  into  the  anterior  border  of  the  left 
auriculo-ventricular  ring,  and  the  anterior  part  of  the  root  of  the 
aorta  and  pulmonary  artery. 

The  Long  or  basial  band,  at  the  anterior  border  of  the  septum, 
passes  directly  backwards  through  the  septum,  forming  its  middle 
layer,  to  the  posterior  ventricular  groove,  where  it  becomes  joined 
by  fibres  derived  from  the  root  of  the  pulmonary  artery.  It  then 
winds  spirally  around  the  middle  and  upper  third  of  the  left  ven- 
tricle to  the  anterior  border  of  the  septum,  where  it  is  connected  by 
means  of  its  internal  surface  with  the  superior  fibres  derived  from 
the  aorta,  which  form  part  of  the  right  wall  of  the  septum.  From 
this  point  it  is  continued  around  the  upper  third  of  the  anterior  and 
posterior  surface  of  the  right  ventricle  to  the  posterior  border  of 
the  septum,  where  it  is  connected  with  the  fibres  constituting  the 
right  surface  of  the  septum  ventriculorum.  At  the  latter  point  the 
fibres  of  this  band  begin  to  be  twisted  upon  themselves,  like  the 
strands  of  a  rope,  the  direction  of  the  twist  being  from  below  up- 
wards. This  arrangement  of  fibres  is  called,  by  Mr.  Searle,  "  the 
rope ;"  it  is  continued  spirally  upwards,  forming  the  brim  of  the 
left  ventricle,  to  the  anterior  surface  of  the  base  of  that  ventricle, 
where  the  twisting  of  the  fibres  ceases.  The  long  band  then  curves 
inwards  towards  the  septum,  and  spreads  out  upon  the  left  surface 
of  the  septum  into  the  broad  and  thick  layer  of  fibres  with  which 
this  description  commenced. 


478  FIBRES  OF  THE  AURICLES. 

The  most  inferior  of  the  fibres  of  the  left  surface  of  the  septum 
ventriculorum,  after  winding  spirally  around  the  internal  surface  of 
the  apex  of  the  left  ventricle,  so  as  to  close  its  extremity,  form  a 
srnall  fasciculus,  which  is  excluded  from  the  interior  of  the  ventricle, 
and  expands  in  a  radiated  manner  over  the  surface  of  the  heart, 
constituting  its  superficial  layer  of  fibres.  The  direction  of  these 
fibres  is,  for  the  most  part,  oblique,  passing  from  left  to  right  on  the 
anterior,  and  from  right  to  left  on  the  posterior  surface  of  the  heart, 
becoming  more  longitudinal  near  its  base,  and  terminating  by  being 
inserted  into  the  fibrous  rings  of  the  auriculo-ventricular  openings, 
and  of  the  pulmonary  artery  and  aorta.  Over  the  right  ventricle 
the  superficial  fibres  are  increased  in  number  by  the  addition  of 
accessory  fibres  from  the  right  surface  of  the  septum,  which  pierce 
the  middle  layer,  and  take  the  same  direction  with  the  superficial 
fibres  from  the  apex  of  the  left  ventricle,  and  of  other  accessory 
fibres  from  the  surface  of  both  ventricles. 

From  this  description  it  will  be  perceived,  that  the  superficial 
layer  of  fibres  is  very  scanty,  and  is  pretty  equally  distributed  over 
the  surface  of  both  ventricles.  The  middle  layer  of  both  ventricles 
is  formed  by  the  two  bands,  short  and  long.  But  the  internal  layer 
of  the  two  ventricles  is  very  differently  constituted :  that  of  the  left 
is  formed  by  the  spiral  expansion  of  the  fibres  of  the  rope,  and  of 
the  two  columnas  papillares;  that  of  the  right  remains  to  be  described. 
The  septum  ventriculorum  also  consists  of  three  layers,  a  left  layer, 
the  radiated  expansion  of  the  rope  and  carnese  columnae  ;  a  middle 
layer,  the  long  band  ;  and  a  right  /a?/e?%  belonging  to  the  proper  wall 
of  the  right  ventricle,  and  continuous  both  in  front  and  behind  with 
the  long  band,  and  in  front  also  with  the  short  band,  and  with  the 
superficial  layer  of  the  right  ventricle. 

The  Internal  layer  of  the  right  ventricle  is  formed  by  fasciculi 
of  fibres  which  arise  from  the  right  segment  of  the  root  of  the  aorta, 
from  the  entire  circumference  of  the  root  of  the  pulmonary  artery, 
and  from  the  bases  of  the  columnae  papillares.  The  fibres  from 
the  root  of  the  aorta,  associated  with  some  from  the  carnese  columnse, 
constitute  a  layer  which  passes  obliquely  forwards  upon  the  right 
side  of  the  septum.  The  superior  fibres  coming  directly  from  the 
aorta  join  the  internal  surface  of  the  long  band  at  the  anterior  bor- 
der of  the  septum,  while  the  lower  two-thirds  of  the  layer  are  con- 
tinuous with  the  internal  surface  of  the  short  band,  some  of  its 
fibres  piercing  that  band  to  augment  the  number  of  superficial 
fibres.  The  fibres  derived  from  the  root  of  the  pulmonary  artery, 
conjoined  with  those  from  the  base  of  one  of  the  columnse  papillares, 
curve  forwards  from  their  origin,  and  wind  obliquely  downwards 
and  backwards  around  the  internal  surface  of  the  wall  of  the  ven- 
tricle to  the  posterior  border  of  the  septum,  where  they'^become 
continuous  with  the  long  band,  directly  that  it  has  passed  backwards 
through  the  septum. 

Fibres  of  the  Auricles. — The  fibres  of  the  auricles  are  disposed  in 
two  layers,  external  and  internal.     The  internal  layer  is  formed  of 


ORGANS  OF  RESPIRATION  AND  VOICE.  479 

fasciculi  which  arise  from  the  fibrous  rings  of  the  auriculo-ventri- 
cular  openings,  and  proceed  upwards  to  enlace  with  each  other, 
and  constitute  the  appendices  auriculorum.  These  fascicuU  are 
parallel  in  their  arrangement,  and  in  the  appendices  form  projec- 
tions and  give  rise  to  the  appearance  which  is  denominated  mus- 
culi  pectinati.  In  their  course  they  give  off  branches  which  con- 
nect adjoining  fasciculi,  and  form  a  columnar  interlacement  between 
them. 

External  Layer. — The  fibres  of  the  right  auricle  having  completed 
the  appendix,  wind  from  left  to  right  around  the  right  border  of  this 
auricle,  and  along  its  anterior  aspect,  beneath  the  appendix,  to  the 
anterior  surface  of  the  septum.  From  the  septum  they  are  con- 
tinued to  the  anterior  surface  of  the  left  auricle,  where  they  separate 
into  three  bands, — superior,  anterior,  and  posterior.  The  superior 
hand  proceeds  onwards  to  the  appendix,  and  encircles  the  apex  of 
the  auricle.  The  anterior  hand  passes  to  the  left,  beneath  the 
appendix,  and  winds  a  broad  layer  completely  around  the  base  of 
the  auricle,  and  through  the  septum  to  the  root  of  the  aorta,  to 
which  it  is  partly  attached,  and  from  this  point  is  continued  onwards 
to  the  appendix,  where  its  fibres  terminate  by  interlacing  with  the 
musculi  pectinati.  The  posterior  hand  crosses  the  left  auricle 
obliquely  to  its  posterior  part,  and  winds  from  left  to  right  around 
its  base,  encircUng  the  openings  of  the  pulmonary  veins  ;  some  of 
its  fibres  are  lost  upon  the  surface  of  the  auricle,  others  are  con- 
tinued onwards  to  the  base  of  the  aorta ;  and  a  third  set,  forming  a 
small  band,  is  prolonged  along  the  anterior  edge  of  the  appendix  to 
its  apex,  where  it  is  continuous  with  the  superior  band.  The  septum 
auriculorum  has  four  sets  of  fibres  entering  into  its  formation ;  1 . 
The  fibres  arising  from  the  auriculo- ventricular  rings  at  each  side ; 
2.  Fibres  arising  from  the  root  of  the  aorta,  which  pass  upwards  to 
the  transverse  band,  and  to  the  root  of  the  superior  cava;  3.  Those 
fibres  of  the  anterior  band  that  pass  through  the  lower  part  of  the 
septum  in  their  course  around  the  left  auricle ;  and  4.  A  slender 
fasciculus,  which  crosses  through  the  septum  from  the  posterior 
part  of  the  right  auriculo-ventricular  ring  to  the  left  auricle. 

It  will  be  remarked  from  this  description,  that  the  left  auricle  is 
considerably  thicker  and  more  muscular  than  the  right. 

Vessels  and  Nerves. — The  Arteries  supplying  the  heart  are  the 
anterior  and  posterior  coronary. 

The  Veins  accompany  the  arteries,  and  empty  themselves  by  the 
common  coronary  vein  into  the  right  auricle.  The  lymphatics 
terminate  in  the  glands  about  the  root  of  the  heart.  The  nerves 
of  the  heart  are  derived  from  the  cardiac  plexuses,  which  are 
formed  by  communicating  filaments  from  the  sympathetic  and 
pneumogastric. 

ORGANS  OF  RESPIRATION  AND  VOICE. 

The  organs  of  respiration  are  the  two  lungs,  with  their  air-tube, 


480  THE  LARYNX. 


the  trachea,  to  the  upper  part  of  which  is  adapted  an  apparatus  of 
cartilages,  constituting  the  organ  of  voice,  or  larynx. 


THE  LARYNX. 

The  Larynx  is  situated  at  the  forepart  of  the  neck,  between  the 
trachea,  and  the  base  of  the  tongue.  It  is  composed  of  cartilages, 
ligaments,  muscles,  vessels,  and  nerves,  and  mucous  membrane. 

The  Cartilages  are  the — 

Thyroid, 

Cricoid, 

Two  Arytenoid, 

Epiglottis. 

The  Thyroid  (^v^sos — s't^Sog,  like  a  shield)  is  the  largest  cartilage  of 
the  larynx :  it  consists  of  Iwo  lateral  portions,  or  alee,  which  meet 
at  an  acute  angle  in  front,  and  form  the  projection  which  is  known 
by  the  name  of  pomum  Adami.  Where  the  pomum  Adami  is  promi- 
nent, a  bursa  mucosa  is  often  found  between  it  and  the  skin. 

Each  ala  is  quadrilateral,  and  forms  a  rounded  border  poste- 
riorly, which  terminates  above,  in  the  superior  carnu,  and  below,  in 
the  inferior  cornu.  Upon  the  side  of  the  ala  is  an  oblique  line,  into 
which  the  sterno-thyroid  muscle  is  inserted,  and  from  which  the 
thyro-hyoid  takes  its  origin.  Behind  this  is  a  vertical  line  which 
gives  origin  to  the  inferior  constrictor  muscle.  In  the  receding 
angle,  formed  by  the  meeting  of  the  two  alee  upon  the  inner  side  of 
the  cartilage,  and  near  to  its  lower  border,  are  attached  the  epi- 
glottis, the  chordae  vocales,  the  thyro-arytenoid,  and  thyro-epiglot- 
tidean  muscles. 

The  Cricoid  (z^i'xoj — d8os,  like  a  ring)  is  a  ring  of  cartilage,  narrow 
in  front  and  broad  behind,  where  it  is  surmounted  by  tivo  rounded 
surfaces,  which  articulate  with  the  arytenoid  cartilages.  Upon  the 
middle  line,  posteriorly,  is  a  vertical  ridge  which  gives  attachment 
to  the  oesophagus,  and  on  each  side  of  the  ridge  are  the  depressions 
which  lodge  the  crico-arytenoidei  postici  muscles.  On  either  side 
of  the  ring  is  a  glenoid  cavity,  which  articulates  with  the  inferior 
cornu  of  the  thyroid  cartilage. 

The  Arytenoid  cartilages  (d^urai'va,  a  pitcher,)*  two  in  number,  are 
triangular  in  form.  They  are  broad  below,  where  they  articulate 
with  the  upper  border  of  the  cricoid,  and  give  attachment  to  the 
crico-arytenoidei  postici,  crico-arytenoidei  laterales,  and  thyro- 
arytcnoidei  muscles,  and  chordas  vocales ;  and  pointed  above,  where 

*  This  derivation  has  reference  to  tlic  appearance  of  both  eartilag^es  taken  together 
and  covered  by  mucous  membrrine.  In  animals,  vvhicli  were  the  principal  subjects  of 
dissection  amon^r  the  ancients,  the  openini"'  of  the  larynx  with  the  arytenoid  cartilages 
bears  a  striking  resemblance  to  the  mouth  of  a  pitcher  having  a  large  spout. 


LIGAMENTS  OF  THE  LARYNX.  481 

they  articulate  with  two  Httle  curved  cartilages,  called  cornicula 
laryngis  (capitula  laryngis).  On  the  posterior  surface  they  are 
concave,  and  lodge  the  arytenoideus  muscle. 

The  Epiglottis  {iitiyXc^TTis,  upon  the  tongue)  is  a  fibro-cartilage  of 
a  yellowish  colour,  studded  with  a  number  of  small  mucous  glands, 
which  are  lodged  in  shallow  pits  upon  its  surface.  It  is  shaped  like 
a  cordate  leaf,  and  is  placed  immediately  in  front  of  the  opening  of 
the  larynx,  which  it  closes  completely  when  the  larynx  is  drawn  up 
beneath  the  base  of  the  tongue.  It  is  attached  by  its  point  to  the 
receding  angle,  betvv^een  the  two  alse  of  the  thyroid  cartilage. 

Two  small  cartilaginous  tubercles  (cuneiform)  are  often  found  in 
the  folds  of  the  mucous  membrane  which  bound  the  opening  of  the 
larynx  laterally. 

Ligaments. — The  Ligaments  of  the  larynx  are  numerous,  and 
may  be  arranged  into  four  groups:  1.  Those  which  articulate  the 
thyroid  with  the  os  hyoides.  2.  Those  which  connect  it  with  the 
cricoid.  3.  Ligaments  of  the  arytenoid  cartilages.  4.  Ligaments 
of  the  epiglottis. 

1.  The  ligaments  which  connect  the  thyroid  cartilage  with  the 
OS  hyoides  are  three  in  number : — 

The  two  Tliyro-liyoidean  ligaments  pass  between  the  superior 
cornua  of  the  thyroid  and  the  extremities  of  the  greater  cornua  of 
the  OS  hyoides  :  a  sesamoid  bone  is  found  in  each. 

The  Thyro-hyoid ean  membrane  is  a  broad  membranous  layer, 
occupying  the  entire  space  between  the  thyroid  cartilage  and  os 
hyoides.     It  is  pierced  by  the  superior  laryngeal  nerve  and  artery. 

2.  The  ligaments  connecting  the  thyroid  to  the  cricoid  cartilage 
are  also  three  in  number : — 

Two  Capsular  ligaments,  with  their  synovial  membranes,  which 
form  the  articulation  between  the  inferior  cornua  of  the  thyroid  and 
the  sides  of  the  cricoid,  and  the  crico-thyroidean  membrane,  through 
which  the  operation  of  laryngotomy  is  performed.  The  latter  is 
generally  crossed  by  a  small  artery,  the  inferior  laryngeal. 

3.  The  ligaments  of  the  arytenoid  cartilages  are  four  in  number : — 
Two  Capsular  ligaments,  and  synovial  membranes,  which  arti- 
culate the  arytenoid  cartilages  with  the  cricoid;  and  the  thyro- 
arytenoid ligaments,  or  chordce  vocales,  which  pass  backwards  from 
the  receding  angle  of  the  thyroid  cartilage,  near  to  its  lower  border, 
to  be  inserted  into  the  bases  of  the  arytenoid  cartilages.  The  space 
between  these  two  ligaments  is  the  glottis,  or  rima  glottidis. 

4.  The  hgaments  of  the  epiglottis  are  five  in  number : — 

1.  Three  folds  of  mucous  membrane,  one  at  the  middle,  and  one 
at  each  side,  called  frcena  e-pi glottidis,  which  hold  the  epiglottis 
back  to  the  tongue.  2.  Epiglotto-fnjoidean  ligainent,  which  connects 
the  epiglottis  to  the  posterior  surface  of  the  os  hyoides.  3.  The 
ligament  which  attaches  the  epiglottis  to  the  receding  angle  of  the 
thyroid  cartilage. 

The  Muscles  of  the  larynx  are  eight  in  number :  the  five  larger 

61 


482  LARYNX. 

are  the  muscles  of  the  chordae  vocales  and  rima  glottidis ;  the  three 
smaller  are  muscles  of  the  epiglottis. 

,  The  five  muscles  of  the  chordae  vocales  and  rima  glottidis  are 
the—  . 

Crico-thyroid, 

Crico-arytenoideus  posticus, 

Crico-arytenoideus  lateralis, 

Thyro-arytenoideus, 

Arytenoideus. 


Fig.  145* 


Fig.  146.f 


The  Crico-thyroid  muscle  arises  from  the  anterior  surface  of  th,e 
cricoid  cartilage,  and  is  inserted  into  the  lower  and  inner  border  of 
the  thyroid. 

The  Crico-arytenoideus  posticus  arises  from  the  depression  on  the 
posterior  surface  of  the  cricoid  cartilage,  and  is  inserted  into  the 
outer  angle  of  the  base  of  the  arytenoid. 

The  Crico-arytenoideus  lateralis  arises  from  the  upper  border  of 
the  side  of  the  cricoid,  and  is  inserted  into  the  outer  angle  of  the 
base  of  the  arytenoid  cartilage. 

The  Thyro-arytenoideus  arises  from  the  receding  angle  of  the  thy- 
roid cartilage,  close  to  the  outer  side  of  the  chorda  vocalis,  and 
passes  backwards  parallel  with  the  chord,  to  be  inserted  into  the 
base  of  the  arytenoid  cartilage. 

The  Arytenoideus  muscle  occupies  the  posterior  concave  surface 
of  the  arytenoid  cartilages,  between  which  it  is  stretched.     It  con- 


*  A  posterior  view  of  the  larynx.  1.  The  tiiyroid  cartilage.  2.  One  of  its  aseend- 
ing  cornua.  3.  One  of  the  descending  cornua.  4.  7.  Tlie  cricoid  cartilage.  5,  5.  The 
arytenoid  cartilages.  6.  The  arytenoideus  muscle,  consisting  of  oblique  and  trans- 
verse fasciculi.     7.  The  crico-arytenoidci  poslici  muscles.     8.  The  epiglottis. 

+  A  side  view  of  the  larynx,  one  ala  of  the  thyroid  cartilage  has  been  removed, 
1.  The  remaining  ala  of  the  thyroid  cartilage.  2.  One  of  the  arytenoid  cartilages. 
3.  One  of  the  cornicula  laryngis.  4.  The  cricoid  cartilage.  5.  The  crico-arytenoideus 
posticus  muscle.  6.  The  crico-arytenoideus  lateralis.  7.  The  thyro-arytenoideus. 
8.  The  crico-thyroidean  membrane.  9.  One  half  of  the  epiglottis.  10.  The  upper 
part  of  the  trachea. 


MUSCLES  OF  THE  LARYNX,  483 

sists  of  three  planes  of  transverse  and  oblique  fibres ;  hence  it  was 
formerly  considered  as  several  muscles,  under  the  names  of  trans- 
versi  and  obliqui. 

The  three  muscles  of  the  epiglottis  are  the — 


Thyro-epiglottideus, 
Aryteno-epiglottideus  superior, 
Aryteno-epiglottideus  inferior  ( 


2i.ryit;no-t;pigiouiut;us  supei  lui, 
Aryteno-epiglottideus  inferior  (Hilton's  muscle). 

The  Thyro-epiglottideus  appears  to  be  formed  by  the  upper  fibres 
of  the  thyro-ary  tenoideus  muscle :  they  spread  out  upon  the  external 
surface  of  the  sacculas  laryngis,  on  which  they  are  lost ;  a  few  of 
the  anterior  fibres  being  continued  onwards  to  the  side  of  the  epi- 
glottis. 

The  Aryteno-epighttideus  superior  consists  of  a  few  scattered 
fibres,  which  pass  forwards  in  the  fold  of  mucous  membrane  form- 
ing the  lateral  boundary  of  the  entrance  into  the  larynx,  from  the 
apex  of  the  arytenoid  cartilage  to  the  side  of  the  epiglottis. 

The  Aryteno-epiglottideus  inferior. — This  muscle  was  discovered 
by  Mr.  Hilton,  and  is  very  important  in  relation  to  the  sacculus 
laryngis,  with  which  it  is  closely  connected.  It  may  be  found  by 
raising  the  mucous  membrane  immediately  above  the  ventricle  of 
the  larynx.  It  arises  by  a  narrow  and  fibrous  origin  from  the  ary- 
tenoid cartilage,  just  above  the  attachment  of  the  chorda  vocalis ; 
and  passing  forwards,  and  a  little  upwards,  expands  over  the  upper 
half,  or  two-thirds  of  the  sacculus  laryngis,  and  is  inserted  by  a 
broad  attachment  into  the  side  of  the  epiglottis. 

Actions. — The  crico-thyroid  and  arytenoid  muscles  are  contractors 
of  the  rima  glottidis ;  the  crico-arytenoideus  posticus  and  lateralis, 
and  the  thyro-arytenoideus,  are  dilators. 

The  crico-thyi'oid  muscles  elongate,  and  thereby  bring  together 
the  chordas  vocales,  by  drawing  the  thyroid  cartilage  downwards 
and  forwards ;  their  posterior  attachment  at  the  arytenoid  cartilages 
being  fixed.  The  arytenoid  muscle  approximates  the  arytenoid 
cartilages,  and  consequently  the  chordae  vocajes,  directly.  The 
crico-thyroidei  postici  being  attached  to  the  outer  angles  of  the 
bases  of  the  arytenoid  cartilages,  draw  them  from  each  other,  and 
stretch  the  chordae  vocales.  The  crico-arytenoidei  laterales  draw 
the  arytenoid  cartilages  from  each  other,  but  relax  the  chordae  vo- 
cales ;  and  the  thyro-arytenoidei  increase  the  width  of  the  glottis, 
by  directly  relaxing  the  chords  vocales. 

The  thyro-epiglottideus  acts  principally  by  compressing  the  glands 
of  the  sacculus  laryngis  and  the  sac  itself:  by  its  attachment  to  the 
epiglottis  it  would  act  feebly  upon  that  valve.  The  aryteno-epiglot- 
tideus superior  serves  to  keep  the  mucous  membrane  of  the  sides  of 
the  opening  of  the  glottis  tense,  when  the  larynx  is  drawn  upwards, 
and  the  opening  closed  by  the  epiglottis.  Of  the  aryteno-epiglotti- 
deus, the  "  functions  appear  to  be,"  writes  Mr.  Hilton,  "  to  compress 
the  subjacent  glands  which  open  into  the  pouch ;  to  diminish  the 


484  MUCOUS  MEMBRANE  OF  THE  LARYNX. 

capacity  of  that  cavity,  and  change  its  form ;  and  to  approximate 
the  epiglottis  and  the  arytenoid  cartilage." 

■  Mucous  JMembrane. — The  larynx  is  lined  by  the  mucous  mem- 
brane, which  is  continued  from  the  mouth  and  pharynx,  and  pro- 
longed onwards  through  the  trachea  and  bronchi  to  the  bronchial 
cells.  The  chordse  vocales  form  two  horizontal  projections  of  the 
mucous  membrane,  and  constitute  the  lateral  boundaries  of  the 
glottis,  or  rima  glottidis.  Immediately  above  the  horizontal  projec- 
tion of  the  chorda  vocalis,  at  each  side,  is  a  depressed  fossa,  the 
ventricle  of  the  larynx.  The  superior  boundary  of  the  ventricle  is 
an  arched  border  of  mucous  membrane,  which  is  very  incorrectly 
termed  the  superior  chorda  vocalis.  If  the  rounded  extremity  of  a 
probe  be  introduced  into  the  ventricle  of  the  larynx,  and  then  directed 
upwards,  it  will  enter  a  considerable  pouch,  which  has  been  recently 
described  by  Mr.  Hilton  as  the  sacculus  laryngis.*  From  the  ven- 
tricle of  the  larynx  the  sacculus  is  continued  upwards,  nearly  as 
high  as  the  upper  border  of  the  thyroid  cartilage,  and  sometimes 
beyond  it.  When  dissected  from  the  interior  of  the  larynx  it  is 
found  covered  by  the  aryteno-epiglottideus  muscle  and  a  fibrous 
membrane,  which  is  attached  to  the  superior  chorda  vocalis  below  ; 
to  the  epiglottis  in  front ;  and  to  the  upper  border  of  the  thyroid 
cartilage  above.  If  examined  from  the  exterior  of  the  larynx,  it 
will  be  seen  to  be  covered  by  the  thyro-epiglottideus  muscle.  On 
the  surface  of  its  mucous  membrane  are  the  openings  of  sixty  or 
seventy  small  follicular  glands,  which  are  situated  in  the  sub-mucous 
tissue,  and  give  to  its  external  surface  a  rough  and  ill-dissected  ap- 
pearance. This  mucous  secretion  is  intended  for  the  lubrication  of 
the  chordse  vocales,  and  is  directed  upon  them  by  two  small  valvular 
folds  of  mucous  membrane,  which  are  situated  at  the  entrance  of 
•  the  sacculus. 

The  Entrance  of  the  larynx  is  formed  by  two  folds  of  mucous 
membrane,  stretched  between  the  apices  of  the  arytenoid  cartilages 
and  the  sides  of  the  epiglottis.  The  arytenoid  glands  and  superior 
aryteno-epiglottidean  muscles  are  situated  within  these  folds. 

*  This  sac  was  discovered  and  described  by  Mr.  Hilton  before  he  was  aware  that  it 
had  already  been  pointed  out  by  the  older  anatomists.  I  myself  made  a  dissection, 
which  I  still  possess,  of  the  same  sac  in  an  enlarged  state  during  the  month  of  August, 
1837,  without  any  knowledge  either  of  Mr.  Hilton's  labours,  or  Morgagni's  account. 
The  sac  projected  considerably  above  the  upper  border  of  the  thyroid  cartilage,  and  the 
extremity  had  been  snipped  off  on  one  side  in  the  removal  of  the  muscles.  The  larynx 
was  presented  to  me  by  Dr.  George  Moore  of  Camberwell :  he  had  obtained  it  from  a 
child  who  died  of  bronchial  disease ;  and  he  conceived  that  this  peculiar  disposition  of 
the  mucous  membrane  might  possibly  explain  some  of  the  symptoms  by  which  the  case 
was  accompanied.  Cruveilhier  made  the  same  discovery  in  equal  ignorance  of  Mor- 
gagni's description,  for  we  read  in  a  note  at  page  677,  vol.  ii.  of  his  Anatomic  Descrip- 
li'ce, — ".I'ai  vu  pour  la  premiere  fois  cette  arri6re  cavit6  chez  un  individu  affects  de 
phthisic  laryngc'ic,  oil  elle  6tait  trds-devcloppt'C.  Je  fis  dcs  recherches  sur  le  larynx 
d'autres  inciividus,  et  jc  trouvai  que  cette  disposition  6tait  constantc.  Je  nc  savais  pas 
alors  que  Morgagni  avait  indique  et  fait  repr^sentcr  la  m6mc  disposition."  Cruveilhier 
compares  its  form  very  aptly  to  a." Phrijgian  casque  "  and  Morgagni's  figure,  Advers. 
1,  Epist.  Anat.  '.i,  plate  9,  fig.  4,  has  the  same  appearance.  But  neither  of  these  anato- 
mists notice  the  follicular  glands  described  by  Mr.  Hilton. 


TRACHEA.  485 

The  Glands  of  the  larynx  are,  1.  The  epiglottic — most  impro- 
perly named — for  it  consists  merely  of  a  mass  of  fat,  situated  be- 
tween the  convexity  of  the  epiglottis  and  the  thyro-hyoid  membrane. 
2.  The  arytenoid  glands,  some  small  granules  found  in  the  folds  of 
mucous  membrane  near  the  apex  of  the  arytenoid  cartilage. 

Vessels  and  Nerves. — The  Arteries  of  the  larynx  are  derived  from 
the  superior  and  inferior  thyroid.  The  nerves  are  the  superior 
laryngeal  and  recurrent  laryngeal ;  both  branches  of  the  pneumo- 
gastric.  The  two  nerves  communicate  with  each  other  freely  ;  but 
the  superior  laryngeal  is  distributed  principally  to  the  mucous  mem- 
brane at  the  entrance  of  the  larynx ;  the  recurrent,  to  the  muscles. 

In  children,  and  in  the  female,  the  larynx  is  less  developed  than 
in  the  adult  male ;  the  thyroid  cartilage  forms  a  more  obtuse  angle, 
and  is  less  firm :  in  the  male  the  angle  is  acute,  and  the  cartilages 
often  converted  into  bone. 

THE  TRACHEA. 

The  Trachea  extends  from  opposite  the  fifth  cervical  vertebra  to 
opposite  the  third  dorsal,  where  it  divides  into  the  two  bronchi.  The 
right  bronchus  larger  than  the  left,  passes  off  nearly  at  right  angles 
to  the  upper  part  of  the  corresponding  lung.  The  left  descends 
obliquely  and  passes  beneath  the  arch  of  the  aorta,  to  reach  the  left 
lung. 

The  Trachea  is  composed  of — 

Fibro-cartilaginous  rings, 
Fibrous  membrane, 
Mucous  membrane. 
Longitudinal  elastic  fibres. 
Muscular  fibres, 
Glands. 

The  Fibro-cartilaginous  rings  are  from  fifteen  to  twenty  in  num- 
ber, and  extend  for  two-thirds  around  the  cylinder  of  the  trachea. 
They  are  deficient  at  the  posterior  part,  where  the  tube  is  completed 
by  fibrous  membrane.  The  last  ring  has  usually  a  triangular  form 
in  front.  The  rings  are  connected  to  each  other  by  a  membrane 
of  yellow  elastic  fibrous  tissue,  which  in  the  space  between  the  ex- 
tremities of  the  cartilages,  posteriorly,  forms  a  distinct  layer. 

The  Longitudinal  elastic  fibres  are  situated  immediately  beneath 
the  mucous  membrane  on  the  posterior  part  of  the  trachea,  and 
enclose  the  entire  cylinder  of  the  bronchial  tubes  to  their  ultimate 
terminations. 

The  Muscular  fibres  form  a  thin  layer,  extending  transversely  be- 
tween the  extremities  of  the  cartilages.*     On  the  posterior  surface 

*  I  have  several  times  seen  a  layer  of  longitudinal  museular  fibres  superadded  to  the 
transverse. — G. 


486  THYROID  GLAND LUNGS. 

they  are  covered  in  by  a  cellulo-fibrous  lamella,  in  which  are  lodged 
the  tracheal  glands.  These  are  small  flattened  ovoid  bodies,  situated 
in  great  number  between  the  fibrous  and  muscular  layers  of  the 
membranous  portion  of  the  trachea,  and  also  between  the  two  layers 
of  elastic  fibrous  tissue  connecting  the  rings.  They  pour  their 
secretion  upon  the  mucous  membrane. 

Thyroid  Gland. 

The  thyroid  gland  is  one  of  those  organs  which  it  is  found  ex- 
tremely difficult  to  classify  from  the  absence  of  any  positive  know- 
ledge with  regard  to  its  function.  It  is  situated  upon  the  trachea, 
and  in  an  anatomical  arrangement  should  therefore  be  considered 
in  this  place,  although  bearing  no  part  in  the  function  of  respiration. 

This  gland  consists  of  two  lobes,  which  are  placed  one  on  each 
side  of  the  trachea,  and  are  connected  with  each  other  by  means  of 
an  isthmus,  which  crosses  its  upper  rings.  There  is  considerable 
variety  in  the  situation  and  breadth  of  this  isthmus ;  which  should 
be  recollected  in  the  performance  of  operations  upon  the  trachea. 
In  structure  it  appears  to  be  composed  of  a  dense  cellular  paren- 
chyma, enclosing  a  great  number  of  vessels.  The  gland  is  larger 
in  young  subjects  and  in  females,  than  in  the  adult  and  males.  It 
is  the  seat  of  an  enlargement  called  bronchocele,  goitre,  or  the  Der- 
byshire neck. 

A  muscle  is  occasionally  found  connected  with  its  upper  border 
or  with  its  isthmus ;  and  attached,  superiorly,  to  the  body  of  the  os 
hyoides,  or  to  the  thyroid  cartilage.  It  was  named  by  Soemmering 
the  "  levator  glandules  thyroidecB.^^ 

Vessels  and  Nerves. — It  is  abundantly  supplied  with  blood  by  the 
superior  and  inferior  thyroid  arteries.  Sometimes  an  additional 
artery  is  derived  from  the  arteria  innominata,  and  ascends  upon  the 
front  of  the  trachea  to  be  distributed  to  the  gland.  The  wounding 
of  this  vessel,  in  tracheotomy,  might  be  fatal  to  the  patient.  The 
nerves  are  derived  from  the  superior  laryngeal  and  sympathetic. 

THE  LUNGS. 

The  lungs  are  two  conical  organs,  situated  one  on  each  side  of 
the  chest,  embracing  the  heart,  and  separated  from  each  other  by  a 
membranous  partition,  the  mediastinum.  On  the  external  or  thoracic 
side  they  are  convex,  and  correspond  with  the  form  of  the  cavity 
of  the  chest ;  internally  they  are  concave,  to  receive  the  convexity 
of  the  heart.  Superiorly  they  terminate  in  a  tapering  cone  which 
extends  above  the  level  of  the  first  rib,  and  inferiorly  they  are  broad 
and  concave,  and  rest  upon  the  convex  surface  of  the  diaphragm. 
Their  posterior  border  is  rounded  and  broad,  the  anterior  sharp  and 
marked  by  one  or  two  deep  fissures,  and  the  inferior  which  sur- 
rounds the  base  is  also  sharp. 

The  colour  of  the  lungs  is  pinkish  gray,  mottled,  and  variously 


STRUCTURE  OF  LUNG. 


487' 


marked  with  black.  The  surface  is  figured  with  irregularly  polygo- 
nal outlines  which  represent  the  lobules  of  the  organ,  and  the  area 
of  each  of  these  polygonal  spaces  is  crossed  by  lighter  lines. 

Fig.  147.* 


Each  lung  is  divided  into  two  lobes,  by  a  long  and  deep  fissure 
which  extends  from  the  posterior  surface  of  the  upper  part  of  the 
organ,  downwards  and  forwards  to  near  the  anterior  angle  of  its 
base. 

In  the  right  lung  the  upper  lobe  is  subdivided  by  a  second  fissui'e, 
which  extends  obliquely  forwards  from  the  middle  of  the  preceding 
to  the  anterior  border  of  the  organ,  and  marks  off  a  small  triangular 
lobe. 

The  Right  lung  is  larger  than  the  leTt,  in  consequence  of  the  in- 
clination of  the  heart  to  the  left  side.  It  is  also  shorter,  from  the 
great  convexity  of  the  liver,  which  presses  the  diaphragm  upwards 
upon  the  right  side  of  the  chest  considerably  above  the  level  of  the 
left.     It  has  three  lobes. 

The  left  lung  is  smaller,  has  but  two  lobes,  but  is  longer  than  the 
rig-ht. 


*  Anatomy  of  the  heart  and  lungs.  1.  The  right  ventricle  ;  tlie  vessels  to  the  right 
of  the  figure  are  the  middle  coronary  artery  and  veins  ;  and  those  to  its  left,  the  ante- 
rior coronary  artery  and  veins.  2.  The  left  ventricle.  3.  The  right  auricle.  4.  The 
left  auricle.  5.  The  pulmonary  artery.  6,  6.  The  right  pulmonary  artery.  7.  The 
left  pulmonary  artery.  8.  The  remains  of  tlie  ductus  arteriosus.  9.  The  arch  of  the 
aorta.  10.  The  superior  vena  cava.  11.  Tlie  right  vena  innominata,  and  the  artcria 
innominata.  12.  The  right  subclavian  artery  and  vein.  13.  Tiic  right  common 
carotid  artery  and  vein.  14.  The  left  vena  innominata.  15.  The  left  carotid  artery 
and  vein.  16.  The  left  subclavian  artery  and  vein.  17.  The  trachea.  18.  The  right 
bronchus.  19.  The  left  bronchus.  20,  20.  The  pulmonary  veins;  18,  6,  20,  form  the 
root  of  the  right  lung;  and  7,  19,  20,  the  root  of  the  left.  21.  The  superior  lobe  of 
the  right  lung.  22.  Its  middle  lobe.  23.  Its  inferior  lobe.  24.  The  superior  lobe  of 
the  left  lung.     25.  Its  inferior  lobe. 


488  KOOT  OF  LUNG, 

Each  lung  is  retained  in  its  place  by  its  root,  which  is  formed  by 
the  pulmonary  artery,  pulmonary  veins  and  bronchial  tubes,  together 
with  the  bronchial  vessels  and  pulmonary  plexuses  of  nerves  The 
large  vessels  of  the  root  of  each  lung  are  arranged  in  a  similar 
order  from  before,  backwards,  on  both  sides,  viz. 

Pulmonary  veins. 
Pulmonary  artery, 
Bronchus. 

From  above,  downwards,  on  the  right  side  this  order  is  exactly 
reversed ;  but  on  the  left  side  the  bronchus  has  to  stoop  beneath  the 
arch  of  the  aorta,  which  alters  its  position  to  the  vessels.  They 
are  thus  disposed  on  the  two  sides : — 

Right.  Left. 

Bronchus,  Artery, 

Artery,  Bronchus, 

Veins.  Veins. 

Structure. — The  lungs  are  composed  of  the  ramifications  of  the 
bronchial  tubes  which  terminate  in  bronchial  cells  (air  cells),  of  the 
ramifications  of  the  pulmonary  artery  and  veins,  bronchial  arteries 
and  veins,  lymphatics  and  nerves ;  the  whole  of  these  structures 
being  held  together  by  cellular  tissue,  which  constitutes  the  "paren- 
chyma. The  parenchyma  of  the  lungs,  when  examined  on  the  sur- 
face or  by  means  of  a  section,  is  seen  to  consist  of  small  polygonal 
divisions,  or  lobules  which  are  connected  to  each  other  by  an  inter- 
lobular cellular  tissue.  These  lobules  again  consist  of  smaller 
lobules,  and  the  latter  are  formed  by  a  cluster  of  air  cells,  in  the 
parietes  of  which  the  capillaries  of  the  pulmonary  artery  and  pul- 
monary veins  are  distributed.* 

Bronchial  tubes. — The  two  bronchi  proceed  from  the  bifurcation 
of  the  trachea  to  their  corresponding  lungs.  The  right  takes  its 
course  nearly  at  right  angles  with  the  trachea,  and  enters  the  upper 
part  of  the  right  lung,  while  the  left,  longer  and  smaller  than  the 
right,  passes  obliquely  beneath  the  arch  of  the  aorta,  and  enters  the 
lung  at  about  the  middle  of  its  root.  Upon  entering  the  lungs  they 
divide  into  two  branches,  and  each  of  these  divides  and  subdivides 
dichotomously  to  their  ultimate  termination  in  small  dilated  sacs, 
the  bronchial  or  pulmonary  cells. 

The  fibro-cartilaginous  rings  which  are  observed  in  the  trachea 
become  incomplete  and  irregular  in  shape  in  the  bronchi,  and  in  the 
smaller  bronchial  tubes  are  lost  altogether.  At  the  termination  of 
these  tubes  the  fibrous  and  muscular  coats  become  extremely  thin, 

*  The  walls  of  the  air  cells  are  so  imperfect  that  all  the  cells  of  any  lobule  commu- 
nicate freely  with  each  other,  whilst  the  contiguous  lobules,  are  separated  by  the  paren- 
chyma. Dr.  Horner's  dissections  exhibit  this  in  a  beautiful  manner.  See  Horner's 
Special  Anatomy,  3d  edition. — G. 


PLEURA MEDIASTINUM.  489 

and  are  probably  continued  upon  the  lining  mucous  membrane  of  the 
air  cells. 

The  Pulmonary  artery,  conveying  the  dark  and  impure  venous 
blood  to  the  lungs,  terminates  in  capillary  vessels,  which  form  a 
minute  network  upon  the  parietes  of  the  bronchial  cells,  and  then 
converge  to  form  the  pulmonary  veins,  by  which  the  arterial  blood, 
purified  in  its  passage  through  the  capillaries,  is  returned  to  the  left 
auricle  of  the  heart. 

The  Bronchial  arteries,  branches  of  the  thoracic  aorta,  ramify 
upon  the  bronchial  tubes  and  in  the  tissue  of  the  lungs,  and  supply 
them  with  nutrition,  while  the  venous  blood  is  returned  by  the 
bronchial  veins  to  the  vena  azygos. 

The  Lymphatics,  commencing  upon  the  surface  and  in  the  sub- 
stance of  the  lungs,  terminate  in  the  bronchial  glands.  These  glands, 
very  numerous  and  often  of  large  size,  are  placed  at  the  roots  of  the 
lungs,  around  the  bronchi,  and  at  the  bifurcation  of  the  trachea.  In 
early  life  they  resemble  lymphatic  glands  in  other  situations ;  but  in 
old  age,  and  often  in  the  adult,  they  are  quite  black,  and  filled  with 
carbonaceous  matter,  and  occasionally  with  calcareous  deposits. 

The  JVerves  are  derived  from  the  pneumogastric  and  sympathetic. 
They  form  two  plexuses, — anterior  pulmonary  plexus,  situated  upon 
the  front  of  the  root  of  the  lungs,  and  composed  chiefly  of  filaments 
from  the  great  cardiac  plexus ;  and  posterior  pulmonary  plexus  on 
the  posterior  aspect  of  the  root  of  the  lungs,  composed  principally 
of  branches  from  the  pneumogastric.  The  branches  from  these 
plexuses  follow  the  course  of  the  bronchial  tubes,  and  are  distributed 
to  the  bronchial  cells. 

PLEURiE. 

Each  lung  is  enclosed,  and  its  structure  maintained,  by  a  serous 
membrane — the  pleura,  which  invests  it  as  far  as  the  root,  and  is 
thence  reflected  upon  the  parietes  of  the  chest.  That  portion  of  the 
membrane  which  is  in  relation  with  the  lung  is  called  pleura  pulmo- 
nalis,  and  that  in  contact  with  the  parietes,  pleura  costalis.  The 
reflected  portion,  besides  forming  the  internal  lining  to  the  ribs  and 
intercostal  muscles,  also  covers  the  diaphragm  and  the  thoracic 
surface  of  the  vessels  at  the  root  of  the  neck. 

The  pleura  must  be  dissected  from  oflf  the  root  of  the  lung,  to 
see  the  vessels  by  which  it  is  formed  and  the  pulmonary  plexuses. 

MEDIASTINUM. 

The  approximation  of  the  two  reflected  pleuras  in  the  middle  line 
of  the  thorax  forms  a  septum  which  divides  the  chest  into  the  two 
pulmonary  cavities.  This  is  the  mediastinum.  The  two  pleurae 
are  not,  however,  in  contact  with  each  other  at  the  middle  line  in 
the  formation  of  the  mediastinum,  but  leave  a  space  between  them 
which  contains  all  the  viscera  of  the  chest  with  the  exception  of  the 
lungs.  The  mediastinum  is  divided  into  the  anterior,  middle,  and 
postet^ior. 

62 


490  ABDOMEN. 

The  Anterior  mediastinum  is  a  triangular  space,  bounded  in  front 
by  the  sternum,  and  on  each  side  by  the  pleura.  It  contains  a  quan- 
tity of  loose  cellular  tissue,  in  which  are  found  some  lymphatic 
glands  and  vessels  passing  upwards  from  the  liver ;  the  remains  of 
the  thymus  gland,  the  origins  of  the  sterno-hyoid,  sterno-thyroid,  and 
triangularis  sterni  muscles,  and  the  internal  mammary  vessels  of  the 
left  side. 

The  Middle  mediastinum  contains  the  heart  enclosed  in  its  peri- 
cardium ;  the  ascending  aorta ;  the  superior  vena  cava ;  the  bifurca- 
tion of  the  trachea ;  the  pulmonary  arteries  and  veins ;  and  the 
phrenic  nerves. 

The  Posterior  mediastinum  is  bounded  behind  by  the  vertebral 
column,  in  front  by  the  pericardium,  and  on  each  side  by  the  pleura. 
It  contains  the  descending  aorta;  the  greater  and  lesser  azygos 
veins,  and  superior  intercostal  vein ;  the  thoracic  duct ;  the  oeso- 
phagus and  pneumogastric  nerves ;  and  the  great  splanchnic  nerves. 

ABDOMEN. 

The  abdomen  is  the  inferior  cavity  of  the  trunk  of  the  body ;  it  is 
bounded  in  front  and  at  the  sides  by  the  lower  ribs  and  abdominal 
muscles  ;  behind,  by  the  vertebral  column  and  abdominal  muscles ; 
above,  by  the  diaphragm  ;  and,  below,  by  the  pelvis :  and  contains 
the  alimentary  canal,  the  organs  subservient  to  digestion,  viz.  the 
liver,  pancreas,  and  spleen,  and  the  organs  of  excretion,  the  kidneys, 
with  the  supra-renal  capsules. 

Regions. — For  convenience  of  description  of  the  viscera,  and  for 
reference  to  the  morbid  affections  of  this  cavity,  the  abdomen  is 
divided  into  certain  districts  or  regions.  Thus,  if  two  transverse 
lines  be  carried  around  the  body,  the  one  parallel  with  the  convexi- 
ties of  the  ribs,  the  other  with  the  highest  points  of  the  crests  of  the 
ilia,  the  abdomen  will  be  divided  into  three  zones.  Again,  if  a  per- 
pendicular line  be  drawn  at  each  side,  from  the  cartilage  of  the 
eighth  rib  to  the  middle  of  Poupart's  ligament,  the  three  primary 
zones  will  each  be  subdivided  into  three  compartments  or  regions,  a 
middle  and  two  lateral. 

The  middle  region  of  the  upper  zone  being  immediately  over  the 
small  end  of  the  stomach,  is  called  epigastric  {^id — /atfT^,  over  the 
stomach).  The  two  lateral  regions  being  under  the  cartilages  of 
the  ribs  are  called  hypochondriac  (vifo — xov^^oi,  under  the  cartilages). 
The  middle  region  of  the  middle  zone  is  the  umbilical;  the  two 
lateral,  the  lumbar.  The  middle  region  of  the  inferior  zone  is  the 
hypogastric  {M — yadrrj^,  below  the  stomach) ;  and  the  two  lateral, 
the  iliac.  In  addition  to  these  divisions,  we  constantly  use  the  term 
inguinal  region,  in  reference  to  the  vicinity  of  Poupart's  ligament. 

Position  of  the  Viscera. — In  the  upper  zone  will  be  seen  the  liver, 
extending  across  from  the  right  to  the  left  side  ;  the  stomach  and 
spleen  on  the  left,  and  the  pancreas  and  duodenum  behind.  In  the 
middle  zone  is  the  transverse  portion  of  the  colon,  with  the  upper 
part  of  the  ascending  and  descending  colon,  omentum,  small  intes- 
tines, mesentery,  and,  behind,  the  kidneys  and  supra-renal  capsules. 


PERITONEUM ^REFLECTIONS. 


491 


In  the  inferior  zone  is  the  lower  part  of  the  omentum  and  small  in- 
testines, the  caecum,  ascending  and  descending  colon  with  the  sigmoid 
flexure,  and  ureters. 

The  smooth  and  polished  surface,  which  the  viscera  and  parietes 
of  the  abdomen  present,  is  due  to  the  peritoneum  which  should  in 
the  next  place  be  studied. 


Fig.  148.* 


PERITONEUM. 

The  Peritoneum  (■n-s^irstveiv  to  extend  around)  is  a  serous  membrane, 
and  therefore  a  shut  sac :  a 
single  exception  exists  in  the 
human  subject  to  this  character^ 
viz.  in  the  female,  where  the 
peritoneum  is  perforated  by  the 
open  extremities  of  the  Fallo- 
pian tubes,  and  is  continuous 
with  their  mucous  lining. 

The  simplest  idea  that  can  be 
given  of  a  serous  membrane, 
which  may  apply  equally  to  all, 
is,  that  it  invests  the  viscus  or 
viscera,  and  is  then  reflected 
upon  the  parietes  of  the  contain- 
ing cavity.  If  the  cavity  con- 
tain only  a  single  viscus,  the 
consideration  of  the  serous 
membrane  is  extremely  simple. 
But  in  the  abdomen,  where 
there  are  a  number  of  viscera, 
the  serous  membrane  passes 
from  one  to  the  other  until  it 
has  invested  the  whole,  before 
it  is  reflected  on  the  parietes. 
Hence  its  reflections  are  a  little 
more  complicated. 

In  tracing  the  reflections  of 
the  peritoneum  in   the  middle 

*  The  reflections  of  the  peritoneum.  D.  The  diaphragm.  L.  The  liver.  S.  The  stomach. 
C.  The  transverse  colon.  D.  The  transverse  duodenum,  P.  The  pancreas.  I.  The 
small  intestines.  R.  The  rectum.  B.  The  urinary  bladder.  1.  The  anterior  layer  of 
the  peritoneum,  lining  the  under  surface  of  the  diaphragm.  2.  The  posterior  layer. 
3.  The  two  layers  passing  to  the  posterior  border  of  the  liver,  and  fjrming  the  coronary 
ligament.  4.  The  lesser  omentum  :  the  two  layers  passing  from  the  under  surface  of 
the  liver  to  the  lesser  curve  of  the  stoma(th.  5.  The  two  layers  meeting  at  the  greater 
curve,  then  passing  downwards  and  returning  upon  themselves,  forming  (6)  the  greater 
omentum.  7.  The  transverse  meso-colon.  8.  The  posterior  layer  traced  upwards  in 
front  of  D,  the  transverse  duodenum,  and  P,  the  pancreas,  to  become  continuous  with 
the  posterior  layer  (2).  9.  The  foramen  of  Winslow  ;  tlie  dotted  line  bounding  this 
foramen  infcriorly,  marks  the  course  of  the  hepatic  artery  forwards,  to  enter  between 
the  layers  of  the  lesser  omentum.  10.  The  mesentery  encircling  the  small  intestine. 
11.  The  reeto-vesical  fold,  formed  by  the  descending  anterior  layer.  12.  The  anterior 
layer  traced  upwards  upon  the  internal  surface  of  the  abdominal  parietes  to  the  layer 
(1),  with  which  the  examination  commenced. 


492  PERITONEUM DUPLICATUEES. 

line,  we  commence  with  the  diaphragm,  which  is  hned  by  two 
layers,  one  from  the  parietes  in  front,  anterior,  and  one  from  the 
parietes  behind,  posterior.  These  two  layers  of  the  same  membrane, 
at  the  posterior  part  of  the  diaphragm,  descend  to  the  upper  surface 
of  the  liver,  forming  the  coronary  and  lateral  ligaments  of  the  liver. 
They  then  surround  the  liver,  one  going  in  front,  the  other  behind 
that  viscus,  and,  meeting  at  its  under  surface,  pass  to  the  stomach, 
forming  the  lesser  omentum.  They  then,  in  the  same  manner,  sur- 
round the  stomach,  and  meeting  at  its  lower  border  descend  for  some 
distance  in  front  of  the  intestines,  and  return  to  the  transverse  colon, 
forming  the  great  omentum;  they  then  surround  the  transverse  colon, 
and  pass  directly  backwards  to  the  vertebral  column,  forming  the 
transverse  meso-colon.  Here  the  two  layers  separate ;  the  posterior 
ascends  in  front  of  the  pancreas  and  aorta,  and  returns  to  the  pos- 
terior part  of  the  diaphragm,  where  it  forms  the  posterior  layer  with 
which  we  commenced.  The  anterior  descends,  invests  all  the  small 
intestines,  and  returning  to  the  vertebral  column  forms  the  mesentery. 
It  then  descends  into  the  pelvis  in  front  of  the  rectum,  which  it 
holds  in  its  place  by  means  of  a  fold  called  meso-rectum,  forms  a 
pouch,  the  recto-vesical  fold,  between  it  and  the  bladder,  ascends 
upon  the  posterior  surface  of  the  bladder,  forming  its  false  ligaments, 
and  returns  upon  the  anterior  parietes  of  the  abdomen  to  the  dia- 
phragm, whence  we  first  traced  it. 

In  the  female,  after  descending  into  the  pelvis  in  front  of  the 
rectum,  it  is  reflected  upon  the  posterior  surface  of  the  vagina  and 
uterus.  It  then  descends  on  the  anterior  surface  of  the  uterus,  and 
forms  at  either  side  the  broad  hgaments  of  that  organ.  From  the 
uterus  it  ascends  upon  the  posterior  surface  of  the  bladder  and  ante- 
rior parietes  of  the  abdomen,  and  is  continued,  as  in  the  male,  to 
the  diaphragm. 

In  this  way  the  continuity  of  the  peritoneum,  as  a  whole,  is  dis- 
tinctly shown,  and  it  matters  not  where  the  examination  commence 
or  where  it  terminate,  still  the  same  continuity  of  surface  will  be 
discernible  throughout.  If  we  trace  it  from  side  to  side  of  the 
abdomen,  we  may  commence  at  the  umbilicus ;  we  then  follow  it 
outwards  lining  the  inner  side  of  the  parietes  to  the  ascending  colon; 
it  surrounds  that  intestine;  it  then  surrounds  the  small  intestine, 
and  returning  on  itself  forms  the  mesentery.  It  then  invests  the 
descending  colon,  and  reaches  the  parietes  on  the  opposite  side  of 
the  abdomen,  whence  it  may  be  traced  to  the  exact  point  from 
which  we  started. 

The  viscera,  which  are  thus  shown  to  be  invested  by  the  perito- 
neum in  its  course  downwards,  are  the — 

Liver, 
Stomach, 
Transverse  colon, 
Small  intestines. 
Pelvic  viscera. 


PERITONEUM OMENTA.  493 

The  folds,  formed  between  these  and  between  the  diaphragm  and 
the  Hver,  are 

(Diaphragm.) 
Broad,  coronary,  and  lateral  Hgaments. 

(Liver.) 
Lesser  omentum. 

(Stomach.) 
Greater  omentum. 

(Transverse  colon.) 

Transverse  meso-colon, 
Mesentery, 
Meso-rectum, 
Recto-vesical  fold. 

False  ligaments  of  the  bladder. 

And  in  the  female,  the 

Broad  ligaments  of  the  uterus. 

The  ligaments  of  the  liver  will  be  examined  with  that  organ. 

The  Lesser  omentum  is  the  dupUcature  passing  between  the  liver 
and  the  upper  border  of  the  stomach.  It  is  extremely  thin,  except- 
ing at  its  right  border,  where  it  is  free,  and  contains  between  its 
layers,  the 

Hepatic  artery, 

Ductus  communis  choledochus, 

Portal  vein. 

Hepatic  plexus  of  nerves. 

Lymphatics. 

These  structures  are  enclosed  in  a  loose  cellular  tissue,  called 
Glisson's  capsule.*  The  relative  position  of  the  three  vessels  is, — 
the  artery  to  the  left,  the  duct  to  the  right,  and  the  vein  between 
and  behind. 

If  the  finger  be  introduced  behind  this  right  border  of  the  lesser 
omentum,  it  will  be  situated  in  an  opening  called  the  foramen  of 
Winslow.-\  In  front  of  the  finger  will  lie  the  right  border  of  the 
lesser  omentum ;  behind  it  the  diaphragm,  covered  by  the  ascending 

*  Francis  Glisson,  Professor  of  Medicine  in  the  University  of  Cambridge,  His 
work,  "  De  An'atomia  Hepatis,"  was  published  in  1654, 

+  Jacob  Benignus  Winslow  :  his  "  Exposition  Anatomique  de  la  Structure  du  Corps 
Humain,"  was  publislied  in  Paris  in  1732, 


494  OMENTA MESENTERY. 

or  posterior  layer  of  the  peritoneum ;  helow,  the  hepatic  artery, 
curving  forwards  from  the  ccehac  axis ;  and  above,  the  lobus 
SpigeUi.  These,  therefore,  are  the  boundaries  of  the  foramen  of 
Winslow,  which  is  nothing  more  than  a  constriction  of  the  general 
cavity  of  the  peritoneum  at  this  point,  arising  out  of  the  necessity 
for  the  hepatic  and  gastric  arteries  to  pass  forwards  from  the 
coeliac  axis  to  reach  their  respective  viscera. 

If  air  be  blown  through  the  foramen  of  Winslow,  it  will  descend 
behind  the  lesser  omentum  and  stomach  to  the  space  between  the 
descending  and  ascending  pair  of  layers,  forming  the  great  omen- 
tum. This  is  sometimes  called  the  lesser  cavity  of  the  peritoneum, 
and  that  external  to  the  foramen  the  greater  cavity ;  in  which  case 
the  foramen  is  considered  as  the  means  of  communication  between 
the  two.  There  is  a  great  objection  to  this  division,  as  it  might 
lead  the  inexperienced  to  believe  that  there  M^ere  really  two  cavi- 
ties. There  is  but  one  only,  the  foramen  of  Winslow  being  merely 
a  constriction  of  that  one,  to  facilitate  the  communication  between 
the  nutrient  arteries  and  the  viscera  of  the  upper  part  of  the  abdo- 
men. 

The  Great  omentum  consists  of  four  layers  of  peritoneum,  the  two 
which  descend  from  the  stomach,  and  the  same  two,  returning  upon 
themselves  to  the  transverse  colon.  A  quantity  of  adipose  substance 
is  deposited  around  the  vessels  which  ramify  through  its  structure. 
It  would  appear  to  perform  a  double  function  in  the  economy.  1st. 
Protecting  the  intestines  from  cold;  and,  2dly.  Facilitating  the  move- 
ment of  the  intestines  upon  each  other  during  their  vermicular 
action. 

The  Transverse  meso-colon  {iJ^s(fog,  middle,  being  attached  to  the 
middle  of  the  cyhnder  of  the  intestine)  is  the  medium  of  connexion 
between  the  transverse  colon  and  the  posterior  wall  of  the  abdomen. 
It  also  affords  to  the  nutrient  arteries  a  passage  to  reach  the  intes- 
tine ;  and  encloses  between  its  layers,  at  the  posterior  part,  the  trans- 
verse portion  of  the  duodenum. 

The  Mesentery  (f^stfov  sWs^ov,  being  connected  to  the  middle  of  the 
cylinder  of  the  small  intestine)  is  the  medium  of  connexion  between 
the  small  intestines  and  the  posterior  wall  of  the  abdomen.  It  is 
oblique  in  its  direction,  being  attached  to  the  posterior  wall,  from 
the  left  side  of  the  second  lumbar  vertebra  to  the  right  iUac  fossa. 
It  retains  the  small  intestines  in  their  places,  and  gives  passage  to 
the  mesenteric  arteries,  veins,  nerves,  and  lymphatics. 

The  Meso-rectum,  in  like  manner,  retains  the  rectum  in  connexion 
with  the  front  of  the  sacrum.  Besides  this,  there  are  some  minor 
folds  in  the  pelvis,  as  the  recto-vesical  fold,  the  false  ligaments  of  the 
bladder,  and  broad  ligaments  of  the  uterus. 

The  Jlppendices  epi/phiccB  are  small  irregular  pouches  of  perito- 
neum, filled  with  fat.  and  situated  like  fringes  upon  the  large  intes- 
tine. 

Three  other  duplicatures  of  peritoneum  are  situated  in  the  sides 
of  the  abdomen ;  they  are  the  gastro-phrenic  ligamen  ,  the  gastro- 


ALIMENTARY  CANAL.  495 

splenic  omentum,  the  ascending  and  descending  meso-colon.  The 
gastro-'phrenic  ligament  is  a  small  duplicature  of  the  peritoneum, 
which  descends  from  the  diaphragm  to  the  extremity  of  the  oeso- 
phagus, and  to  the  lesser  curve  of  the  stomach.  The  g astro-splenic 
omentum  is  the  dupHcature  which  connects  the  spleen  to  the  sto- 
mach. The  ascending  meso-colon  is  the  fold  which  connects  the 
upper  part  of  the  ascending  colon  with  the  posterior  wall  of  the 
abdomen ;  and  the  descending  meso-colon,  that  which  retains  the 
sigmoid  flexure,  in  connexion  with  the  abdominal  wall. 

Structure  of  serous  membrane. — Serous  membrane  consists  of  two 
layers,  an  external  or  cellular  layer,  and  an  internal  layer  or  epithe- 
lium. The  cellular  layer  upon  its  outer  surface  is  rough  and  vascu- 
lar, and  adherent  to  surrounding  structures ;  but  on  its  inner  surface 
is  dense  and  smooth,  and  wholly  deficient  of  vessels  carrying  red 
blood.  The  smooth  and  brilliant  surface  of  serous  membrane  is  due 
to  a  distinct  epithelium,  which  has  been  shown  by  the  excellent  re- 
searches of  Henle,  to  be  composed  of  laminae  of  vesicles,  and  of 
flattened  polygonal  scales  with  central  nuclei,  hke  the  epithelium  of 
mucous  membrane.  Dr.  Henle  has  observed  this  structure,  which 
may  be  easily  demonstrated  with  a  good  microscope  upon  the  sur- 
face of  all  the  serous  membranes  of  the  body,  upon  the  surface  of 
the  lining  membrane  of  arteries  and  veins,  and  upon  synovial  mem- 
branes. 

The  general  characters  of  a  serous  membrane  are  its  resemblance 
to  a  shut  sac,  and  its  secretion  of  a  peculiar  fluid,  resembUng  the 
serum  of  the  blood ;  but  the  former  of  these  characters  is  not  abso- 
lutely essential  to  the  identity  of  a  serous  membrane;  for,  as  we 
have  shown  above,  the  peritoneum  in  the  female  is  perforated  by  the 
extremities  of  the  Fallopian  tubes ;  while  in  aquatic  reptiles  there  is 
a  direct  communication  between  its  cavity  and  the  medium  in  which 
they  live. 

From  the  variable  nature  of  the  secretion  of  these  membranes, 
they  have  been  divided  into  two  classes — the  true  serous  membranes, 
viz.  the  arachnoid,  pericardium,  pleurae,  peritoneum,  and  tunicae  va- 
ginales,  which  pour  out  a  secretion  containing  but  a  small  propor- 
tion of  albumen ;  and  the  synovial  membranes  and  bursae  which 
secrete  a  fluid  containing  a  larger  quantity  of  albumen. 

ALIMERTTARY    CANAL. 

The  Alimentary  canal  is  a  musculo-membranous  tube,  extending 
from  the  mouth  to  the  anus.  It  is  variously  named  in  the  different 
parts  of  its  course ;  hence  it  is  divided  into  the 

Mouth, 
Pharynx, 
(Esophagus, 
Stomach, 


496  ALIMENTARY    CANAL. 

{  Duodenum, 
Small  intestine  }  Jejunum, 


(lie 


um. 


(  Caecum, 
Large  intestine  }  Colon, 

( Rectum.  ^ 

The  Mouth  is  the  irregular  cavity  which  contains  the  organs  of 
taste  and  the  principal  instruments  of  mastication.  It  is  bounded  in 
front  by  the  lips  ;  on  either  side  by  the  internal  surface  of  the  cheeks ; 
above  by  the  hard  palate  and  teeth  of  the  upper  jaw ;  below  by  the 
tongue,  by  the  mucous  membrane  stretched  between  the  arch  of  the 
lower  jaw  and  the  under  surface  of  the  tongue,  and  by  the  teeth  of 
the  inferior  maxilla;  and  behind  by  the  soft  palate  and  fauces. 

The  Lips  are  two  fleshy  folds,  formed  externally  by  common  in- 
tegument, and  internally  by  mucous  membrane,  and  containing 
between  these  two  layers  the  muscles  of  the  lips,  a  quantity  of  fat, 
and  numerous  small  labial  glands.  They  are  attached  to  the  sur- 
face of  the  upper  and  lower  jaw,  and  each  lip  is  connected  to  the 
gum  in  the  middle  hne  by  a  fold  of  mucous  membrane,  the  frsenum 
labii  superioris  and  frsenum  labii  inferioris,  the  former  being  the 
larger. 

The  Cheeks  (buccas)  are  continuous  on  either  hand  with  the  lips, 
and  form  the  sides  of  the  face ;  they  are  composed  of  integument, 
a  large  quantity  of  fat,  muscles,  mucous  membrane,  and  buccal 
glands. 

The  mucous  membrane  lining  the  cheeks  is  reflected  above  and 
below  upon  the  sides  of  the  jaws,  and  is  attached  posteriorly  to  the 
anterior  margin  of  the  ramus  of  the  lower  jaw.  At  about  its  mid- 
dle, opposite  to  the  second  molar  tooth  of  the  upper  jaw,  is  a  papilla, 
upon  which  may  be  observed  a  small  opening,  the  entrance  of  the 
duct  of  the  parotid  gland. 

The  Hard  palate  is  a  dense  structure,  composed  of  mucous  mem- 
brane, palatal  glands,  fibrous  tissue,  vessels  and  nerves,  and  firmly 
connected  to  the  palate  processes  of  the  superior  maxillary  and 
palate  bones.  It  is  bounded  in  front  and  on  each  side  by  the  alveolar 
processes  and  gums,  and  is  continuous  behind  with  the  soft  palate. 
It  is  marked  along  the  middle  line  by  an  elevated  raph^,  and  pre- 
sents upon  each  side  of  the  raphe  a  number  of  transverse  ridges 
and  grooves.  Near  the  anterior  extremity,  and  immediately  behind 
the  middle  incisor  teeth,  is  a  papilla  which  corresponds  with  the 
termination  of  the  naso-palatine  canal,  and  has  been  supposed  to  be 
endoM'ed  with  a  peculiar  sensibility. 

The  Gums  are  composed  of  a  thick  and  dense  mucous  membrane, 
which  is  closely  adherent  to  the  periosteum  of  the  alveolar  pro- 
cesses, and  embraces  the  necks  of  the  teeth.  They  are  remarkable 
for  their  hardness  and  insensibility,  and  for  their  close  contact, 
without  adhesion,  to  the  surface  of  the  tooth.     From  the  neck  of 


SALIVARY  GLANDS.  497 

the  tooth  they  are  reflected  into  the  alveolus,  and  become  continuous 
with  the  periosteal  membrane  of  that  cavity. 

The  Tongue  has  been  already  described  as  an  organ  of  sense ;  it 
is  invested  by  mucous  membrane,  which  is  reflected  from  its  under 
part  upon  the  inner  surface  of  the  lower  jaw,  and  constitutes,  with 
the  muscles  beneath,  the  floor  of  the  mouth.  Upon  the  under  sur- 
face of  the  tongue,  near  to  its  anterior  part,  the  mucous  membrane 
forms  a  considerable  fold,  which  is  called  the  frsenum  linguas ;  and 
on  each  side  of  the  frajnum  is  a  large  papilla,  tiie  commencement 
of  the  duct  of  the  submaxillary  gland,  and  several  smaller  openings, 
the  ducts  of  the  sublingual  gland. 

The  Soft 'palate  (velum  pendulum  palati)  is  a  fold  of  mucous  mem- 
brane situated  at  the  posterior  part  of  the  mouth.  It  is  continuous, 
superiorly  with  the  hard  palate,  and  is  composed  of  mucous  mem- 
brane, palatal  glands,  and  muscles.  Hanging  from  the  middle  of  its 
inferior  border  is  a  small  rounded  process,  the  uvula ;  and  passing 
outwards  from  the  uvula  on  each  side  are  two  curved  folds  of  the 
mucous  membrane,  the  arches,  or  pillars  of  the  palate.  The  anterior 
pillar  is  continued  downwards  to  the  side  of  the  base  of  the  tongue, 
and  is  formed  by  the  projection  of  the  palato-glossus  muscle.  The 
posterior  pillar  is  prolonged  downwards  and  backwards  into  the 
pharynx,  and  is  formed  by  the  convexity  of  the  palato-pharyngeus 
muscle.  These  two  pillars,  closely  united  above,  are  separated  below 
by  a  triangular  interval  or  niche,  in  which  the  tonsil  is  lodged. 

The  Tonsils  (amygdate)  are  two  glandular  organs,  shaped  like 
almonds,  and  situated  between  the  anterior  and  posterior  pillar  of 
the  soft  palate,  on  each  side  of  the  fauces.  They  are  cellular  in 
texture,  and  composed  of  an  assemblage  of  mucous  folhcles,  which 
open  upon  the  surface  of  the  gland.  Externally,  they  are  invested 
by  the  pharyngeal  fascia,  which  separates  them  from  the  superior 
constrictor  muscle  and  internal  carotid  artery,  and  prevents  an  ab- 
scess from  opening  in  that  direction.  In  relation  to  surrounding 
parts,  they  correspond  with  the  angle  of  the  lower  jaw. 

The  space  included  between  the  soft  palate  and  the  root  of  the 
tongue  is  the  isthmus  of  the  fauces.  It  is  bounded  above  by  the  soft 
palate :  on  each  side  by  the  pillars  of  the  soft  palate  and  tonsils ; 
and  below  by  the  root  of  the  tongue.  It  is  the  opening  between 
the  mouth  and  pharynx. 


SALIVARY  GLANDS. 

Communicating  with  the  mouth  are  the  excretory  ducts  of  three 
pairs  of  salivary  glands,  the  parotid,  submaxillary,  and  sublingual. 

The  Parotid  gland  {ifa^a,  near,  oZg,  cjto?,  the  ear),  the  largest  of 
the  three,  is  situated  immediately  in  front  of  the  external  ear,  and 
extends  superficially  for  a  short  distance  over  the  masseter  muscle, 
and  deeply  behind  the  ramus  of  the  lower  jaw.  It  reaches  infe- 
riorly  to  below  the  level  of  the  angle  of  the  lower  jaw,  and  poste- 
riorly to  the  mastoid  process,  slightly  overlapping  tlie  insertion. of 

63 


498  SUBMAXILLARY SUBLINGUAL  GLAND. 

the  sterno-mastoid  muscle.  Embedded  in  its  substance  are  the 
external  carotid  artery,  temporo-maxillary  vein,  and  facial  nerve ; 
and,  emera;incr  from  its  anterior  border,  the  tranverse  facial  artery 
and  branches  of  the  pes  anserinus  ;  and  above,  the  temporal  artery. 
The  duct  of  the  parotid  gland  (Stenon's*  duct)  commences  at  the 
papilla  upon  the  internal  surface  of  the  cheek,  opposite  the  second 
molar  tooth  of  the  upper  jaw  ;  and,  piercing  the  buccinator  muscle, 
crosses  the  masseter  to  the  anterior  border  of  the  gland,  where  it 
divides  into  several  branches,  which  subdivide  and  ramify  through 
its  structure,  to  terminate  in  the  small  cascal  pouches  of  which  the 
gland  is  composed.  A  small  branch  is  generally  given  off  from  the 
duct  while  crossing  the  masseter  muscle,  which  forms,  by  its  rami- 
fications and  terminal  dilatations,  a  small  glandular  appendage,  the 
socia  parotidis.  Stenon's  duct  is  remarkably  dense  and  of  con- 
siderable thickness,  while  the  area  of  its  canal  is  extremely  small. 

The  Submaxillary  gland  is  situated  in  the  posterior  angle  of  the 
submaxillary  triangle  of  the  neck.  It  rests  upon  the  hyo-glossus 
and  mylo-hyoideus  muscles,  and  is  covered  in  by  the  body  of  the 
lower  jaw  and  by  the  deep  cervical  fascia.  It  is  separated  from 
the  parotid  gland  by  the  stylo-maxillary  ligament,  and  from  the 
subbn^Tual  by  the  mylo-hyoideus  muscle.  Embedded  among  its 
lobules  is  the  facial  artery  and  the  submaxillary  ganglion. 

The  Excreiorxj  duct  (Wharton's)  of  the  submaxillary  gland  com- 
mences upon  the  papilla,  by  the  side  of  the  frjEnum  lingua,  and 
passes  backwards  beneath  the  mylo-hyoideus  and  resting  upon  the 
hyo-glossus  muscle,  to  the  middle  of  the  gland,  where  it  divides  into 
numerous  branches,  which  ramify  through  the  structure  of  the  gland 
to  its  ccecal  terminations.  It  lies  in  its  course  against  the  mucous 
membrane  forming  the  floor  of  the  mouth,  and  causes  a  projecting 
rido;e  upon  its  surface. 

The  Subungual  is  an  elongated  and  flattened  gland,  situated  be- 
neath the  mucous  membrane  of  the  floor  of  the  mouth,  on  each 
side  of  the  frcenum  linguas.  It  is  in  relation  above  with  the  mucous 
membrane  ;  in  front  with  the  depression  by  the  side  of  the  symphy- 
sis of  the  lower  jaw ;  externalhj  with  the  mylo-hyoideus  muscle ; 
and  internally  w^ith  the  lingual  nerve  and  genio-hyo-glossus  muscle. 

It  pours  its  secretion  into  the  mouth  by  seven  or  eight  small  ducts, 
which  commence  by  small  openings  on  each  side  of  the  frasnum 
lingua). 

Structure.— "IhQ  salivary  are  conglomerate  glands,  consisting  of 
lobes,  which  are  made  up  of  angular  lobules,  and  these  of  still 
smaller  lobules. 

The  smallest  lobule  is  apparently  composed  of  granules,  which 
are  minute  cacal  pouches,  formed  by  the  dilatation  of  the  extreme 
ramifications  of  the  ducts.     These  minute  ducts  unite  to  form  lobu- 

*  Nicholas  Stenon,  an  anatomist  of  great  research.  He  discovered  the  parotid  duct 
while  in  Paris.  He  was  appointed  professor  of  medicine  in  Copenhagen  in  1673.  His 
work,  "  De  MuscuUh  et  Ghuidulis  Oi)scrvationc9,"  was  published  in  IGGd. 


PHARYNX ITS  OPENINGS. 


499 


lar  ducts,  and  the  lobular  ducts  constitute  by  their  union  a  single 
excretory  duct. 

The  cascal  pouches  are  connected  by  cellular  tissue,  so  as  to 
form  a  minute  lobule ;  the  lobules  are  held  together  by  a  more  con- 
densed cellular  layer ;  and  the  larger  lobes  are  enveloped  by  a  dense 
cellulo-fibrous  capsule,  which  is  firmly  attached  to  the  deep  cervical 
fascia. 

Vessels  and  Nerves. — The  parotid  gland  is  abundantly  supplied 
with  arteries  by  the  external  carotid ;  the  submaxillary  by  the 
facial ;  and  the  sublingual  by  the  sublingual  branch  of  the  hngual 
artery. 

The  JVerves  of  the  parotid  gland  are  derived  from  the  auricular 
branch  of  the  inferior  maxillary  nerve,  from  the  auricularis  mag- 
nus,  and  from  the  nervi  molles  of  the  external  carotid  artery.  The 
submaxillary  gland  is  supplied  by  the  branches  of  the  submaxillary 
ganglion,  and  by  filaments  from  the  mylo-hyoidean  nerve ;  and  the 
sublingual  by  filaments  from  the  submaxillary  ganglion  and  gusta- 
tory nerve, 

PHARYNX. 

The  pharynx  (<p«.fu7f,  the  throat)  is  a  musculo-membranous  sac, 
situated  upon  the  cervical  portion  of  the  vertebral  column,  and 
extending  from  the  base  of  the  skull  to  a  point  corresponding  with 
the  cricoid  cartilage  in  front,  and  the  fifth  cervical  vertebra  behind. 
It  is  composed  of  mucous  membrane,  muscles,  vessels,  and  nerves, 
and  is  invested  by  a  strong  fascia,  situated 
between  the  mucous  membrane  and  mus-  Fig.  149* 

cles,  which  serves  to  connect  it  with  the 
basilar  process  of  the  occipital  bone  and 
with  the  petrous  portions  of  the  temporal 
bones.  Upon  its  anterior  part  it  is  incom- 
plete, and  has  opening  into  it  seven  fora- 
mina, viz. 

Posterior  nares,  two. 

Eustachian  tubes,  two, 

Mouth, 

Larynx, 

(Esophagus. 

The  Posterior  nares  are  the  two  large 
openings  at  the  upper  and  front  part  of  the 
pharynx.    On  each  side  of  these  openings, 

*  The  plinrynx  laid  open  from  behind.  1.  A  section  carried  transversely  throusfh 
the  base  of  the  skull.  2,  2.  The  walls  of  the  pharynx  drawn  to  each  side.  3,  3.  The 
posterior  nares,  separated  by  the  vomer.  4.  The  extremity  of  the  Eustachian  tube  of 
one  side.  5.  The  soft  palate.  6.  The  posterior  pillar  of  the  soft  palate.  7.  Its  ante- 
rior pillar ;  the  tonsil  is  seen  sitiintcd  in  the  niche  between  the  two  pillars.  8.  The 
root  of  the  tongue,  partly  concealed  by  the  uvula.  9.  The  epiglottis,  overhanging  (10) 
the  opening  of  the  glottis.  U.  The  posterior  part  of  the  larynx.  12.  The  opening 
into  the  (Esophagus.     13.  The  external  surface  of  the  oesophagus.     14.  Tiic  trachea. 


500  THE  STOMACH. 

and  slightly  above  the  posterior  termination  of  the  inferior  turbi- 
nated bone,  is  the  irregular  depression  in  the  mucous  membrane, 
marking  the  entrance  of  the  Eustachian  tube.  Beneath  the  poste- 
rior nares  is  the  large  opening  into  the  mouth,  partly  veiled  by  the 
soft  palate ;  and,  beneath  the  root  of  the  tongue,  the  opening  of  the 
lar}aix.  The  cesophageal  opening  is  the  lower  constricted  portion 
of  the  pharynx. 

(Esophagus. — The  oesophagus  (o'/siv,  to  bear,  (paysiv,  to  eat)  is  a 
shghtly  flexuous  canal,  inclining  to  the  left  in  the  neck,  to  the  right 
in  the  upper  part  of  the  thorax,*  and  again  to  the  left  in  its  course 
through  the  posterior  mediastinum ;  it  commences  at  the  termina- 
tion of  the  pharynx,  opposite  the  lower  border  of  the  cricoid  carti- 
lage and  fifth  cervical  vertebra,  and  descends  the  neck,  behind  and 
rather  to  the  left  of  the  trachea.  It  then  passes  behind  the  arch  of 
the  aorta,  and  along  the  posterior  mediastinum,  lying  in  front  of  the 
thoracic  aorta,  to  the  cesophageal  opening  in  the  diaphragm,  where 
it  enters  the  abdomen,  and  terminates  at  the  cardiac  orifice  of  the 
stomach  at  a  point  about  opposite  to  the  tenth  dorsal  vertebra.  The 
oesophagus  is  flattened  and  narrow  in  the  cervical  region,  and  cylin- 
drical in  the  rest  of  its  course;  its  largest  diameter  is  met  with  near 
to  the  lower  part  of  its  course. 

THE  STOMACH. 

The  stomach  is  an  expansion  of  the  alimentary  canal,  situated  in 
the  left  hypochondriac,  and  extending  into  the  epigastric  region.  It 
is  directed  somewhat  obliquely  from  above  downwards,  from  left  to 
right  and  from  before  backwards  ;  and  in  the  female  where  the 
injurious  system  of  tight-lacing  has  been  pursued  is  longer  than  in 
the  male.  On  account  of  the  peculiarity  of  its  form,  it  is  divided 
into  a  greater  or  splenic,  and  a  lesser  or  pyloric,  end;  a  lesser  cur- 
vature above,  and  a  greater  curvature  below ;  an  anterior  and  a 
posterior  surface ;  a  cardiac  orifice,  and  a  pyloric  orifice.  The  great 
end  is  not  only  of  large  size,  but  expands  beyond  the  point  of 
entrance  of  the  oesophagus,  and  is  embraced  by  the  concave  sur- 
face of  the  spleen.  The  pylorus  is  the  small  and  contracted  extre- 
mity of  the  organ ;  near  to  its  extremhy  is  a  small  dilatation  which 
was  called  by  Willis  the  antrum  of  the  pylorus.  The  two  curva- 
tures give  attachment  to  the  peritoneum ;  the  upper  curve  to  the 
lesser  omentum,  and  the  lower  to  the  greater  omentum.  The 
anterior  surface  looks  upwards  and  forwards,  and  is  in  relation 
with  the  diaphragm  which  separates  it  from  the  viscera  of  the 
thorax  and  from  the  six  lower  ribs,  with  the  left  lobe  of  the  liver, 
and  in  the  epigastric  region,  with  the  abdominal  parietes.  The 
posterior  surface  looks  downwards  and  backwards,  and  is  in  rela- 
tion with  the  diaphragm,  the  pancreas,  the  third  portion  of  the 

*  Cruveilhior  remarks  that  this  inflexion  explains  the  obstruction  which  a  bougie 
sometimes  meets  with  in  its  passage  along  the  oceophagus  opposite  the  first  rib. 


THE  DUODENUM.  501 

duodenum,  the  transverse  meso-colon,  the  right  kidney,  and  supra- 
renal capsule ;  this  surface  forms  the  anterior  boundary  of  that  cul 
de  sac  of  the  peritoneum  which  is  situated  behind  the  lesser  omen- 
tum and  extends  into  the  greater  omentum. 

Small  Intestines. — The  small  intestine  is  about  twenty-five  feet  in 
length,  and  is  divisible  into  three  portions,  duodenum,  jejunum,  and 
ileum. 

Yig.  150.* 


The  Duodenum  (called  ^ukxa^axTM'kov  by  Herophilus)  is  some- 
what larger  than  the  rest  of  the  small  intestines,  and  has  received 
its  name  from  being  about  equal  in  length  to  the  breadth  of  twelve 
fingers.  Commencing  at  the  pylorus,  it  ascends  obliquely  back- 
wards to  the  under  surface  of  the  liver :  it  next  descends  peiyendi- 
cularly  in  front  of  the  right  kidney,  and  then  passes  nearly  trans- 
versely across  the  third  lumbar  vertebra;  terminating  in  the 
jejunum  on  the  left  side  of  the  second  lumbar  vertebra,  where  it  is 
crossed  by  the  superior  mesenteric  artery  and  portal  vein.  The 
first  or  oblique  portion  of  its  course,  between  two  and  three  inches,  is 
completely  enclosed  by  the  peritoneum :  it  is  in  relation,  above  with 

*  A  vertical  and  longitudinal  section  of  the  stomach  and  duodenum,  made  in  such  a 
direction  as  to  inchide  the  two  orifices  of  the  stomacli.  1.  The  oesophagus;  upon  its 
internal  surface  the  plicated  arrangement  of  the  cuticular  epitliclium  is  shown.  2. 
The  cardiac  orifice  of  the  stomach,  around  which  the  fringed  border  of  the  cuticular 
epithelium  is  seen.  3.  The  great  end  of  the  stomach.  4.  Its  lesser  or  pyloric  end. 
5.  The  lesser  curve.  6.  The  greater  curve.  7.  Tiie  dilatation  at  liie  lesser  end  of 
the  stomach  which  received  from  Willis  the  name  of  antrum  of  the  pylorus.  This 
may  be  regarded  as  the  rudiment  of  a  second  stomach.  8.  The  rugas  of  the  stomach 
formed  by  the  mucous  membrane:  their  longitudinal  direction  is  sliown.  9.  Tlie 
pylorus.  10.  The  oblique  portion  of  the  duodenum.  11.  The  descending  portion.  "12. 
The  pancreatic  duct,  and  the  ductus  connnunis  choledochus  close  to  tlicir  termina- 
tion. 13.  The  papilla  upon  which  the  ducts  open.  14.  The  transverse  portion  of  the 
duodenum.  15.  The  commencement  of  the  jejunum.  In  the  interior  of  the  duodenum 
and  jejunum,  the  valvulce  comiivcntes  are  seen. 


502  JEJUNUM ILEUM C^CUBI. 

the  liver  and  neck  of  the  gall-bladder ;  in  front  with  the  greater 
omentum  and  abdominal  parietes ;  and  behind  with  the  right  border 
of  the  lesser  omentum  and  its  vessels.  The  second  or  perpendicular 
portion  is  situated  altogether  behind  the  peritoneum ;  it  is  in  rela- 
tion by  its  a7iterior  surface  with  the  commencement  of  the  arch  of 
the  colon  ;  by  its  posterior  surface  with  the  concave  margin  of  the 
right  kidney,  the  inferior  vena  cava,  and  the  ductus  communis 
choledochas ;  by  its  right  border  with  the  ascending  colon :  and  by 
its  left  border  with  the  pancreas.  The  ductus  communis  choledo- 
chus  and  pancreatic  duct  open  into  the  internal  and  posterior  side 
of  the  perpendicular  portion,  a  little  below  its  middle.  The  third 
or  transverse  portion  of  the  duodenum  lies  between  the  diverging 
layers  of  the  transverse  meso-colon,  with  which  and  with  the 
stomach  it  is  in  relation  in  front;  above  it  is  in  contact  with  the 
lower  border  of  the  pancreas,  the  superior  mesenteric  artery  and 
portal  vein  being  interposed ;  and  behind  it  rests  upon  the  inferior 
vena  cava  and  the  aorta. 

'  The  Jejunum  (jejunus,  empty)  is  named  from  being  generally 
found  empty.  It  forms  the  upper  two-fifths  of  the  small  intestine  ; 
commencing  at  the  duodenum  on  the  left  side  of  the  second  lumbar 
vertebra,  and  terminating  in  the  ileum.  It  is  thicker  to  the  touch 
than  the  rest  of  the  intestine,  and  has  a  pinkish  tinge  from  contain- 
ing more  mucous  membrane  than  the  ileum. 

The  Ileum  {s'lXsiv,  to  twist,  to  convolute)  includes  the  remaining 
three-fifths  of  the  small  intestine.  It  is  somewhat  smaller  in  caUbre, 
thinner  in  texture,  and  paler  than  the  jejunum  ;  but  there  is  no  mark 
by  which  to  distinguish  the  termination  of  the  one  or  the  commence- 
ment of  the  other.  It  terminates  in  the  right  iliac  fossa,  by  opening 
at  an  obtuse  angle  into  the  colon. 

The  jejunum  and  ileum  are  surrounded  above  and  at  the  sides  by 
the  colon ;  in  front  they  are  in  relation  with  the  omentum  and  abdo- 
minal parietes ;  they  are  retained  in  their  position  by  the  mesentery, 
which  connects  them  with  the  posterior  wall  of  the  abdomen ;  and 
below  they  descend  into  the  cavity  of  the  pelvis.  At  about  the  lower 
third  of  the  ileum  a  pouch-like  process  or  diverticulum  of  the  intes- 
tine is  occasionally  seen.  This  is  a  remnant  of  embryonic  structure, 
and  is  formed  by  the  obliteration  of  the  vitelline  duct  at  a  short  dis- 
tance from  the  cylinder  of  the  intestine. 

Large  intestine. — The  large  intestine,  about  five  feet  in  length,  is 
sacculated  in  appearance,  and  is  divided  into  the  ccecum,  colon  and 
rectum. 

The  CcBcum  (csecus,  blind)  is  the  blind  pouch,  or  cul-de-sac,  at 
the  commencement  of  the  large  intestine.  It  is  situated  in  the  right 
ihac  fossa,  and  is  retained  in  its  place  by  the  peritoneum,  which 
passes  over  its  anterior  surface ;  its  posterior  surface  is  connected 
b/ loose  cellular  tissue  with  the  iliac  fascia.  Attached  to  its  ex- 
tremity is  the  appendix  vermiformis,  a  long  worm-shaped  tube,  the 
rudiment  of  the  lengthened  ca3cum  found  in  all  mammiferous  animals 
except  man  and  the  higher  quadrumana.     The  appendix  varies  in 


COLON RECTUM.  503 

length,  from  one  to  five  or  six  inches ;  it  is  about  equal  in  diameter 
to  a  goose-quill,  and  is  connected  with  the  posterior  and  left  aspect 
of  the  caBcum  near  to  the  extremity  of  the  ileum.  It  is  usually  more 
or  less  coiled  upon  itself,  and  retained  in  that  coil  by  a  falciform 
duplicature  of  peritoneum.  Its  canal  is  extremely  small,  and  the 
orifice  by  which  it  opens  into  the  ccecum  not  unfrequently  provided 
with  an  incomplete  valve.  Occasionally  the  peritoneum  invests  the 
caecum  so  completely  as  to  constitute  a  meso-ca?cum,  which  per- 
mits of  an  unusual  degree  of  movement  in  this  portion  of  the  intes- 
tine, and  serves  to  explain  the  occurrence  of  hernia  of  the  cfficum 
upon  the  left  side.  The  caecum  is  the  most  dilated  portion  of  the 
large  intestine. 

The  Colon  is  divided  into  ascending,  transverse,  and  descending. 
The  ascending  colon  passes  upwards  from  the  right  ihac  fossa, 
through  the  right  lumbar  region,  to  the  under  surface  of  the  liver. 
It  then  bends  inwards,  and  crosses  the  upper  part  of  the  umbilical 
region  under  the  name  of  transverse  colon,  and  on  the  left  side  de- 
scends {descending  colon)  through  the  left  lumbar  region  to  the  left 
iliac  fossa,  where  it  makes  a  remarkable  curve  upon  itself,  which  is 
called  the  sigmoid Jlexure. 

The  ascending  colon,  the  most  dilated  portion  of  the  large  intes- 
tine, next  to  the  caecum,  is  retained  in  its  position  in  the  abdomen 
either  by  the  peritoneum  passing  simply  in  front  of  it  or  by  a  narrow 
meso-colon.  It  is  in  relation  in  front  wdth  the  small  intestine  and 
with  the  abdominal  parietes  ;  behind  with  the  quadratus  lumborum 
muscle  and  with  the  right  kidney ;  internally  with  the  small  intestine 
and  with  the  perpendicular  portion  of  the  duodenum ;  and  by  its 
upper  extremity  with  the  under  surface  of  the  liver  and  with  the 
gall-bladder.  The  transverse  colon,  the  longest  portion  of  the  large 
intestine,  forms  a  curve  across  the  cavity  of  the  abdomen,  the  con- 
vexity of  which  looks  forwards  and  sometimes  downwards.  It  is 
in  relation  by  its  iL-pper  surface  with  the  liver,  the  gall-bladder,  the 
stomach,  and  with  the  lower  extremity  of  the  spleen  ;  by  its  lower 
surface  with  the  small  intestine ;  by  its  anterior  surface  with  the 
anterior  layers  of  the  great  omentum  and  with  the  abdominal  pari- 
etes ;  and  by  its  posterior  surface  with  the  transverse  meso-colon. 
The  descending  colon  is  smaller  in  calibre,  and  is  situated  more 
deeply  than  the  ascending  colon.  Its  relations  are  precisely  similar. 
The  sigmoid  flexure  is  the  narrowest  part  of  the  colon ;  it  curves  in 
the  first  place  upwards  and  then  downwards,  and  to  one  or  the  other 
side,  and  is  retained  in  its  place  by  a  meso-colon.  It  is  in  relation 
in  front  with  the  small  intestine  and  with  the  abdominal  parietes; 
behind  with  the  iliac  fossa ;  and  on  either  side  with  the  small  intes- 
tine. 

The  Rectum  is  the  termination  of  the  large  intestine.  It  has  re- 
ceived its  name,  not  so  much  from  the  direction  of  its  course,  as 
from  the  straightness  of  its  form  in  comparison  with  the  colon.  It 
descends  from  opposite  the  left  sacro-iliac  symphysis,  in  front  of 
the  sacrum,  forming  a  gentle  curve  to  the  right  side,  and  then  re- 


504  STRUCTURE  OP  INTESTINES. 

turning  to  the  middle  line;  near  the  extremity  of  the  coccyx  it 
curves  backwards  to  terminate  at  the  anus  at  about  an  inch  in  front 
of  the  apex  of  that  bone.  The  rectum,  therefore,  forms  a  double 
flexure  in  its  course,  the  one  being  directed  from  side  to  side,  the 
other  from  before  backwards.  It  is  smaller  in  calibre  at  its  upper 
part  than  the  sigmoid  flexure,  but  becomes  gradually  larger  as  it 
descends,  and  its  lower  extremity,  previously  to  its  termination  at 
the  anus,  forms  a  dilatation  of  considerable  but  variable  size. 

With  reference  to  its  relations,  the  rectum  is  divided  into  three 
portions;  the  first,  including  half  its  length,  extends  to  about  the 
middle  of  the  sacrum,  is  completely  surrounded  by  peritoneum,  and 
connected  to  the  sacrum  by  means  of  the  meso-rectum.  It  is  in  re- 
lation above  with  the  left  sacro-iliac  symphysis  and  below  with  the 
branches  of  the  internal  iliac  artery,  and  with  the  sacral  plexus  of 
nerves ;  one  or  two  convolutions  of  the  small  intestine  are  interposed 
between  the  front  of  the  rectum  and  the  bladder  in  the  male ;  and 
between  the  rectum  and  the  uterus  with  its  appendages  in  the  female. 
The  second  portion,  about  three  inches  in  length,  is  closely  attached 
to  the  surface  of  the  sacrum,  and  covered  by  peritoneum  only  in 
front ;  it  is  in  relation  by  its  lower  part  with  the  base  of  the  bladder, 
vesiculae  seminales,  and  the  prostate  gland,  and  in  the  female  with 
the  vagina.  The  third  portion  curves  backwards  from  opposite  the 
prostate  gland  to  terminate  at  the  anus ;  it  is  embraced  by  the  leva- 
tores  ani,  and  is  about  one  inch  and  a  half  in  length.  It  is  separated 
from  the  membranous  portion  of  the  urethra  by  a  triangular  space ; 
in  the  female  this  space  intervenes  between  the  vagina  and  the  rec- 
tum, and  constitutes  by  its  base  the  perineum. 

The  Anus  is  situated  at  a  little  more  than  an  inch  in  front  of  the 
extremity  of  the  coccyx.  The  integument  around  it  is  covered  with 
hairs,  and  is  drawn  into  numerous  radiated  plaits  which  are  oblite- 
rated during  the  passage  of  faeces.  The  margin  of  the  anus  is  pro- 
vided with  an  abundance  of  sebaceous  glands,  and  the  cuticle  may 
be  seen  terminating  by  a  fringed  and  scalloped  border,  at  a  few  lines 
above  the  extremity  of  the  opening. 

Structure  of  the  Intestinal  Canal. — The  pharynx  has  three  coats; 
a  mucous  coat,  a  fibrous  coat  derived  from  the  pharyngeal  fascia, 
and  a  muscular  layer.  The  oesophagus  has  but  two  coats,  the  mu- 
cous and  muscular.  The  stomach  and  intestines  have  three,  raucous 
and  muscular,  and  an  external  serous  investment,  derived  from  the 
peritoneum. 

Mucous  coat. — The  mucous  membrane  of  the  mouth  invests  the 
whole  internal  surface  of  that  cavity,  and  is  reflected  along  the 
parotid,  submaxillary,  and  sublingual  ducts,  into  the  corresponding 
glands.  It  terminates  anteriorly  upon  the  outer  margin  of  the  red 
border  of  the  lips,  and  posteriorly  is  continuous  with  the  mucous 
lining  of  the  pharynx.  The  mucous  membrane  of  the  pharynx 
is  continuous  with  the  mucous  lining  of  the  Eustachian  tubes,  the 
nares,  the  mouth  and  the  larynx.  In  the  oesophagus  it  is  thick,  very 
loosely  connected  with  the  muscular  coat,  and  is  disposed  in  longi- 
tudinal pliccn.     In  the  stomach  the  mucous  membrane  is  thin  and 


MUCOUS  MEMBRANE  OF  ST03IACH.  505 

vascular  at  the  great  extremity,  and  becomes  thicker  and  Ughter  in 
colour  towards  the  pyloric  extremity.  It  is  formed  into  plaits  or 
rugcE,  which  are  disposed  for  the  most  part  in  a  longitudinal  direc- 
tion. The  rugffi  are  most  numerous  towards  the  lesser  end  of  the 
stomach ;  while  around  the  cardiac  orifice  they  assume  a  radiated 
arrangement.  At  the  pylorus  the  mucous  membrane  forms  a  cir- 
cular or  spiral  fold  which  constitutes  a  part  of  the  apparatus  of  the 
pyloric  valve.  In  the  lower  half  of  the  duodenum,  the  whole  length 
of  the  jejunum,  and  in  the  upper  part  of  the  ileum,  it  forms  valvular 
folds  called  valvulcB  conniventes,  which  are  several  lines  in  breadth 
in  the  lower  part  of  the  duodenum  and  upper  portion  of  the  jejunum, 
and  diminish  gradually  in  size  towards  each  extremity.  These 
folds  do  not  entirely  surround  the  cyhnder  of  the  intestine,  but  ex- 
tend for  about  one  half  or  three-fourths  of  its  circumference.  In  the 
lower  half  of  the  ileum  the  mucous  lining  is  without  folds ;  hence 
the  thinness  of  the  coats  of  this  intestine  as  compared  with  the  jeju- 
num and  duodenum.  At  the  termination  of  the  ileum  in  the  cascum, 
the  mucous  membrane  forms  two  folds,  which  are  strengthened  by 
the  muscular  coat,  and  project  into  the  ca3cum.  These  are  the  ilio- 
ccecal  valve  (Valvula  Bauhini).  In  the  csecum  and  colon  the  mucous 
membrane  is  raised  into  crescentic  folds,  which  correspond  with  the 
sharp  edges  of  the  sacculi ;  and,  in  the  rectum,  it  forms  three  val- 
vular folds,*  one  of  which  is  situated  near  the  commencement  of  the 
intestine ;  the  second,  extending  from  the  side  of  the  tube,  is  placed 
opposite  the  middle  of  the  sacrum ;  and  the  third,  which  is  the 
largest  and  most  constant,  projects  from  the  anterior  wall  of  the 
intestine  opposite  the  base  of  the  bladder.  Besides  these  folds,  the 
membrane  in  the  empty  state  of  the  intestine  is  thrown  into  longitu- 
dinal plaits,  somewhat  similar  to  those  of  the  oesophagus ;  these 
have  been  named  the  columns  of  the  rectum. f 

Structure  of  Mucous  Membrane. — This  membrane  is  analogous  to 
the  cutaneous  covering  of  the  exterior  of  the  body,  and  resembles 
that  tissue  very  closely  in  its  structure.  It  is  composed  of  three 
layers,  an  epitkeUum,  a  p?~oper  mucous,  and  vl  fibrous  layer. 

The  Epithelium  is  the  cuticle  of  the  mucous  membrane.  Through- 
out the  pharynx  and  oesophagus  it  resembles  the  cuticle,  both  in 
appearance  and  character.  It  is  continuous  with  the  cuticle  of  the 
skin  at  the  margin  of  the  lips,  and  terminates  by  an  irregular  bor- 
der at  the  cardiac  orifice  of  the  stomach.  At  the  opposite  extre- 
mity of  the  canal  it  terminates  by  a  scalloped  border  just  within  the 
verge  of  the  anus.  In  the  mouth  it  is  composed  of  several  laminae 
of  oval  vesicles  and  thin  angular  scales.  Each  vesicle  and  each 
scale  possesses  a  central  nucleus,  and  within  the  nucleus  is  a  minute 

*  Mr.  Houston,  "  On  the  Mucous  Membrane  of  the  Rectum."  Dublin  Hospital  Re- 
ports, vol.  V. 

t  The  spaces  between  the  columns  of  the  rectum  become  closed  at  the  anus  so  as  to 
form  a  series  of  pouches  represented  in  the  accompanying  cut.  These  pouclics  are 
sometimes  dilated  and  produce  a  disease  first  described  by  Dr.  Physick.  (See  Gibson's 
Surgery.)  The  mucous  membrane  of  the  rectum  is  connected  to  the  muscular  coat 
by  a  very  loose  cellular  tissue  as  in  the  oesophagus. — G. 

61 


506 


POUCHES  AND  COLUMNS  OF  RECTUM. 


nucleus-corpuscle.  According  to  Mr.  Nasmyth*  the  deepest  lamina 
of  the  epithelium  appears  to  consist  of  nuclei  only,  in  the  next  the 
investing  vesicle  is  developed ;  the  vesicles  by  degrees  enlarge  and 
become  flattened,  and  in  the  superficial  lamina  are  converted  into 
thin  scales.  The  nuclei,  the  vesicles,  and  the  scales,  are  connected 
together  by  a  glutinous  fluid  of  the  consistence  of  jelly,  which  con- 


tains an  abundance  of  minute  opaque  granules.  The  scales  of  the 
superficial  layer  overlap  each  other  by  their  margins.  During  the 
natural  functions  of  the  mucous  membrane  the  superficial  scales 
exfoliate  continually  and  give  place  to  the  deeper  layers.  In  the 
stomach  and  intestines  these  bodies  are  pyriform  in  shape,  and  have 
a  columnar  arrangement,  the  apices  being  applied  to  the  papillary 

*  InvcstigatLons  into  tlie  structure  of  the  Epithelium,  presented  to  the  medical  sec- 
tion of  the  British  Medical  Association,  in  1839,  published  in  a  work  entitled  "Three 
Memoirs  on  the  Devclopement  of  the  Teeth  and  Epithelium."  1841. 

t  A  vertical  section  of  the  anterior  pariotcs  of  tlie  anus,  with  the  whole  canal  dis- 
played  so  as  to  sJiow  the  relations  of  the  sacculi  of  the  middle  region,  and  their  rela- 
tions to  the  surroundinjr  parts,  tlieir  orifices  hcinfr  marked  with  bristles,  a,  a.  Co- 
lumns  of  the  rectum,  k,  b.  Rudiments  of  columns,  c.  Internal  sphincter,  f.  Ex- 
ternal sphincter,  i.  Rudimentary  or  imperfect  sacculi.  K,  k.  Radiated  folds  of  the 
skin,  terminating  on  the  surface  of  the  nates,    n.  A  bristle  in  one  of  the  sacs. — G. 


STRUCTURE  OF  MUCOUS  MEMBRANE.  507 

surface  of  the  membrane,  and  the  bases  forming  by  their  approxi- 
mation the  free  intestinal  surface.  Each  cokimn  is  provided  with  a 
central  nucleus  and  nucleus-corpuscle,  which  gives  to  its  middle  a 
swollen  appearance ;  and,  from  the  transparency  of  its  structure, 
the  nucleus  may  be  seen  through  the  base  of  the  column,  when  ex- 
amined from  the  surface.  Around  the  circular  villi  the  columns, 
from  being  placed  perpendicularly  to  the  surface,  have  a  radiated 
arrangement.  The  columnar  epithelium  is  produced  in  the  same 
manner  with  the  laminated  epithelium,  in  nuclei,  vesicles,  and  co- 
lumns, and  the  latter  are  continually  thrown  off  to  give  place  to 
successive  layers. 

The  Proper  mucous,  or  Papillary  layer  is  analogous  to  the  papil- 
lary layer  of  the  skin,  and,  like  it,  is  the  secreting  structure  by 
which  the  epithelium  is  produced.  Its  surface  presents  several 
varieties  of  appearance  when  examined  in  the  different  parts  of  its 
extent.  In  the  stomach  it  forms  polygonal  cells,  into  the  floor  of 
which  the  gastric  follicles  open.  In  the  small  intestine  it  presents 
numerous  minute,  projecting  papillas,  called  villi.  The  villi  are  of 
two  kinds,  cylindricai  and  laminated,  and  so  abundant  as  to  give  to 
the  entire  surface  a  beautiful  velvety  appearance.  In  the  large  in- 
testine the  surface  is  composed  of  a  fine  network  of  minute  polygo- 
nal cells,  more  numerous  than  those  of  the  stomach,  but  resembling 
them  in  receiving  the  secretion  from  numerous  perpendicular  folli- 
cles into  their  floors.* 

The  Fibrous  layer  (submucous,  nervous)  is  the  membrane  of 
support  to  the  mucous  membrane,  as  is  the  corium  to  the  papillary 
layer  of  the  skin.  It  gives  to  the  mucous  membrane  its  strength 
and  resistance,  is  but  loosely  connected  with  the  mucous  layer,  but 
is  firmly  adherent  to  the  muscular  stratum,  and  is  called,  in  the 
older  works  on  anatomy,  the  "  nervous  coat" 

In  the  loose  cellular  tissue  connecting  the  mucous  with  the  fibrous 
layer,  are  situated  the  glands  and  foUicles  belonging  to  the  mucous 
membrane  :  these  are  the — 

Pharyngeal  glands, 

(Esophageal  glands. 

Gastric  follicles. 

Duodenal  glands,  (Brunner's), 

Gland  uIeb  solitarise, 

Glandulas  aggregatse  (Peyer's), 

Simple  folhcles  (Lieberkiihn's). 

The  Pliarijngeal  glands  are  situated  in  considerable  numbers 
beneath  the  mucous  membrane  of  the  pharynx,  particularly  around 
the  posterior  nares.     Two  of  these  glands,  of  larger  size  than  the 

*  The  first  notice  of  the  true  structure  of  mucous  membrane  appeared  in  the 
American  Journal  of  Medical  Sciences,  and  was  from  the  pen  of  Professor  Horner. 
The  preparations  vvliicli  he  made  at  the  time  are  in  the  Wistar  Museum,  and  illustrate 
the  structure  beautifully. — G. 


508  GLANDS  OF  INTESTINES. 

rest,  and  lobulated  in  structure,  occupy  the  margin  of  the  opening 
of  the  Eustachian  tube. 

.  The  (Esophageal  glands  are  small  lobulated  bodies,  situated  in 
the  submucous  tissue,  and  opening  upon  the  surface  of  the  oeso- 
phagus by  a  long  excretory  duct,  which  passes  obliquely  through 
the  raucous  membrane. 

The  Gastric  follicles  are  long  tubular  follicular  glands,  situated 
perpendicularly  side  by  side  in  every  part  of  the  mucous  membrane 
of  the  stomach.  At  their  terminations  they  are  dilated  into  small 
lateral  pouches,  which  give  them  a  clustered  appearance.  This 
character  is  more  clearly  exhibited  at  the  pyloric  than  at  the  cardiac 
end  of  the  stomach.  They  are  intended,  very  probably,  for  the 
secretion  of  the  gastric  fluid. 

The  Duodenal  or  Brunner''s  glands,*  are  small  flattened  granular 
bodies,  compared  collectively  by  Von  Brunn  to  a  second  pancreas. 
They  resemble  in  structure  the  small  salivary  glands,  so  abundant 
beneath  the  mucous  membrane  of  the  mouth  and  lips  ;  and,  like 
them,  they  open  upon  the  surface  by  minute  excretory  ducts.  They 
are  limited  to  the  duodenum. 

The  Solitary  glands  are  of  two  kinds,  those  of  the  small  and  those 
of  the  large  intestine.  The  former  are  small  circular  patches,  sur- 
rounded by  a  zone  or  wreath  of  simple  follicles.  When  opened,  they 
are  seen  to  consist  of  a  small  flattened  saccular  cavity,  containing  a 
mucous  secretion,  but  having  no  excretory  duct.  They  are  chiefly 
found  in  the  lower  part  of  the  ileum.  The  solitary  glands  of  the 
large  intestine  are  most  abundant  in  the  CKCum  and  appendix  casci ; 
they  are  small  circular  projections,  flattened  upon  the  surface,  and 
perforated  in  the  centre  by  a  minute  excretory  opening. 

The  Aggregate,  or  Peyer^s  glands,]  are  situated  near  to  the  lower 
end  of  the  ileum,  and  occupy  that  portion  of  the  intestine  which  is 
opposite  the  attachment  of  the  mesentery.  To  the  naked  eye  they 
present  the  appearance  of  oval  disks,  covered  with  small  irregular 
fissures ;  but  with  the  aid  of  the  microscope  they  are  seen  to  be 
composed  of  numerous  small  circular  patches,  surrounded  by  simple 
follicles,  like  the  solitary  glands  of  the  small  intestine.  Each  patch 
corresponds  with  a  flattened  and  closed  sac,  situated  beneath  the 
membrane,  but  having  no  excretory  opening,  and  the  interspace 
between  the  patches  is  occupied  by  flattened  villi. 

The  Simple  follicles,  or  follicles  of  LicberkiJhn,  are  small  pouches 
of  the  mucous  layer,  dispersed  in  immense  numbers  over  every  part 
of  the  mucous  membrane. 

Muscular  coat. — The  muscular  coat  of  the  pharynx  consists  of 
five  pairs  of  muscles,  which  have  been  already  described.  The 
muscular  coat  of  the  rest  of  the  alimentary  canal  is  composed  of 
two  planes  of  fibres,  an  external  longitudinal,  and  an  internal  cir- 
cular. 

'*  Jolin  Conrad  von  Brunn;  "Glandulan  Dnodcni  seu  Pancreas  Socundariiim,"  1715, 
t  Jolin  Conrad  I'cyer,  an  nnaf.omist  of  SeliaufTlianscn,  in  Switzerland,     ITis  essay, 
"  I>c  Glandulis  Intostinoriirn,"  waa  published  in  K)77. 


MUSCULAR  COAT.  509 

The  (Esophagus  is  very  muscular ;  its  longitudinal  fibres  are  con- 
tinuous above  with  the  pharynx,  and  are  attached  in  front  to  the 
vertical  ridge  on  the  posterior  surface  of  the  cricoid  cartilage ;  the 
uppermost  circular  fibres  are  also  attached  on  each  side  to  the 
cricoid  cartilage.  Below,  both  sets  of  fibres  are  continued  upon 
the  stomach.  On  the  stomach  the  longitudinal  fibres  are  most  appa- 
rent along  the  lesser  curve,  and  the  circular  at  the  smaller  end.  At 
the  pylorus  the  latter  are  aggregated  into  a  thick  circular  ring, 
which,  with  the  spiral  fold  of  mucous  membrane,  constitutes  the 
pyloric  valve.  At  the  great  end  of  the  stomach  a  new  order  of 
fibres  is  introduced,  having  for  their  object  to  strengthen  and  com-, 
press  that  extremity  of  the  organ.  They  are  directed  more  or  less 
horizontally  from  the  great  end  towards  the  lesser  end,  and  are 
generally  lost  upon  the  sides  of  the  stomach  at  about  its  middle ; 
these  are  the  oblique  fibres. 

The  Small  intestine  is  provided  with  both  layers,  equally  distri- 
buted over  the  entire  surface.  At  the  termination  of  the  ileum  the 
circular  fibres  are  continued  into  the  two  folds  of  the  ilio-CEBcal 
valve,  while  the  longitudinal  fibres  pass  onwards  to  the  large  intes- 
tine. In  the  large  intestine  the  longitudinal  fibres  commence  at 
the  appendix  vermiformis  and  are  collected  into  three  bands,  an 
anterior,  broad;  and  two  posterior  and  narrower  bands.  These 
bands  are  nearly  one  half  shorter  than  the  intestine,  and  give  to  it 
the  sacculated  appearance  which  is  characteristic  of  the  cfficum 
and  colon.  In  the  descending  colon  the  posterior  bands  usually  unite 
and  form  a  single  band.  From  this  point  the  two  bands  are  con- 
tinued downwards  upon  the  sigmoid  flexure  to  the  rectum,  around 
which  they  spread  out  and  form  a  thick  and  very  muscular  lon- 
gitudinal layer.  The  circular  fibres  in  the  csecum  and  colon  are 
exceedingly  thin ;  in  the  rectum  they  are  thicker,  and  at  its  lower 
extremity  they  are  aggregated  into  the  thick  muscular  ring  which 
is  called  the  internal  sphincter  ani.* 

Serous  Coat. — The  pharynx  and  oesophagus  have  no  covering 
of  serous  membrane.  The  alimentary  canal  within  the  abdomen 
has  a  serous  layer,  derived  from  the  peritoneum. 

The  Stomach  is  completely  surrounded  by  the  peritoneum  ex- 
cepting along  the  line  of  junction  of  the  great  and  lesser  omentum. 
T\\Q  first  or  oblique  portion  of  the  duodenum  is  also  completely  in- 

*  Mr.  Wilson  does  not  seem  to  have  paid  the  same  close  attention  !o  the  anatomy  of 
the  anus  as  to  other  parts  of  the  body,  and  we  here  find  a  deficiency  in  the  description 
which  we  shall  endeavour  to  supply. 

The  Muscular  coat  of  the  rectum  consists  of  much  stronger  fasciculi  than  that  of 
the  colon  ;  the  transverse  fibres  terminate  at  the  anus  by  agfgrcgating^  into  a  ring  wliicii 
is  called  the  internal  sphincter  muscle,  as  in  c  fig-.  152.  The  longitudinal  fibres  being 
outside  of  the  transverse,  when  they  reach  the  internal  sphincter  wind  around  it  and 
are  inserted  into  the  submucous  coat  from  one  to  four  inches  above  the  anus.  They 
tlius  Ibrm  a  pulley-like  arrangement  which  everts  the  mucous  membrane  in  defecation 
and  is  the  active  agent  in  j)rodueing  prolapsus  ani.  I  have  observed  that  wlicn  hwmor- 
rhoids  exist  many  of  the  fibres  run  to  be  inserted  into  them,  hence  their  ready  extru- 
sion when  the  patient  is  directed  to  force  them  down.  The  following  cut  exhibits  this 
arrangement.     See  Horner's  Special  Anatomy,  1836. — G, 


510 


VESSELS  OF  INTESTINES. 


eluded  by  the  serous  membrane  with  the  exception  of  the  points 

of   attachment  of   the   omenta. 
Fig.  152.*  The  descending  fortion  has  mere- 

ly a  partial  covering  on  its  an- 
terior surface.  The  transverse 
portion  is  also  behind  the  perito- 
neum, being  situated  between  the 
two  layers  of  the  transverse  me- 
so-colon,  and  has  but  a  partial 
coverinsr.  The  rest  of  the  small 
intestine  is  completely  invested 
by  it,  excepting  along  the  con- 
cave border  to  which  the  mesen- 
tery is  attached.  The  ccecum  is 
more  or  less  invested  by  the  peri- 
toneum, the  more  frequent  dispo- 
sition being  that  in  which  the  in- 
testine is  surrounded  for  three- 
fourths  only  of  its  circumference. 
The  ascending  and  the  descend- 
ing colon  are  covered  by  the  se- 
rous membrane  only  in  front. 
The  transverse  colon  is  invested 
completely,  with  the  exception  of  the  lines  of  attachment  of  the 
greater  omentum  and  transverse  meso-colon.  And  the  sigmoid 
Jlexure  is  entirely  surrounded,  with  the  exception  of  the  part  cor- 
responding with  the  junction  of  the  left  meso-colon.  The  upper 
third  of  the  rectum  is  completely  enclosed  by  the  peritoneum;  the 
middle  third  has  an  anterior  covering  only,  and  the  inferior  third 
none  whatsoever. 

Vessels  and  JVerves. — The  Arteries  of  the  alimentary  canal,  as 
they  supply  the  tube  from  above  downwards,  are  the  pterygo-pala- 
tine,  ascending  pharyngeal,  superior  thyroid,  and  inferior  thyroid  in 
the  neck;  oesophageal  in  the  thorax ;  gastric,  hepatic,  splenic,  superior 
and  inferior  mesenteric  in  the  abdomen ;  and  inferior  mesenteric, 
iliac,  and  internal  pudic  in  the  pelvis.  The  veins  from  the  abdomi- 
nal alimentary  canal  unite  to  form  the  vena  portae.  The  lymphatics 
and  lacteals  open  into  the  thoracic  duct. 


*  A  vertical  section  of  the  parietcs  of  the  anus,  passing  through  the  middle  line  of 
one  of  the  cohiinns  of  tlic  rectum,  and  tiic  neiglibouring  parts,  c.  The  internal 
spliinctcr,  with  its  arched  fibres  transversely  divided,  n,  d.  The  jjlane  of  arclicd  fibres 
of  the  muscular  coat,  similarly  divided,  e.  Tlie  point  of  greatest  contraction  of  the  in- 
ternal sphincter,  f.  The  external  sphincter,  a.  The  point  of  grcntcst  contraction  of 
the  same  muscle,  ir.  The  plane  of  longitudinal  fibres  of  tlie  muscular  coat,  longitudi- 
nally  divided,  i.  Some  of  those  fibres  terminating  in  tlie  internal  sphincter,  k.  Others, 
terminating  in  the  external  sphincter.  1.  The  remaining  longitudinal  fibres,  collected 
into  a  scrnitcri(hrious  fasciculus,  passing  over  tiie  lovirer  margin  of  the  internal  spliineter, 
to  be  reverted  upward  within  tlie  duplicature  of  the  column,  m.  These  reverted  fibres 
again  becoming  muscular,  and  terminating  in  the  mucous  coat.  l.  The  mucous  coat, 
w.  A  bristle  in  oncof  tiic  sacs. — G. 


THE  LIVER. 


511 


The  Nerves  of  the  pharynx  and  oBsophagus  are  derived  from'the 
glosso-pharyngeal,  pneumogastric,  and  sympathetic.  The  nerves  of 
the  stomach  are  the  pneumogastric  and  sympathetic  branches  from 
the  solar  plexus ;  and  those  of  the  intestinal  canal  are  the  superior 
and  inferior  mesenteric  and  hypogastric  plexuses.  The  extremity 
of  the  rectum  is  supplied  by  the  coccygeal  nerves  from  the  spinal 
cord. 

THE  LIVER. 

The  liver  is  a  conglomerate  gland  of  large  size,  appended  to  the 
alimentary  canal,  and  performing  the  double  office  of  separating 
impurities  from  the  venous  blood  of  the  chylo-poietic  viscera  pre- 
viously to  its  return  into  the  general  venous  circulation,  and  of 
secreting  a  fluid  necessaiy  to  chylification,  the  bile.    It  is  the  largest 

Fig.  153.* 


organ  in  the  body,  weighing  about  four  pounds,  and  measuring 
through  its  longest  diameter  about  twelve  inches.  It  is  situated  in 
the  right  hypochondriac  region,  and  extends  across  the  epigastrium 
into  the  left  hypochondriac,  frequently  reaching  by  its  left  extremity 
to  the  upper  end  of  the  spleen.  It  is  placed  obliquely  in  the  abdo- 
men ;  its  convex  surface  looking  upwards  and  forwards,  and  the 
concave  downwards  and  backwards.  The  anterior  border  is 
sharp,  free,  and  marked  by  a  deep  notch,  the  posterior  rounded 
and  broad.  It  is  in  relation,  superiorly  and  posteriorly  with  the 
diaphragm,  and  inferiorly  with  the  stomach,  ascending  portion  of 
the  duodenum,  transverse  colon,  right  supra-renal  capsule  and  right 
kidney,  and  corresponds  by  its  free  border  with  the  lower  margin 
of  the  ribs. 


*  The  upper  surface  of  the  liver.  1.  The  right  lobe.  2.  The  left  lobe.  3.  The  an- 
terior or  free  border.  4.  The  posterior  or  rounded  border.  5.  The  broad  ligament. 
6.  The  round  ligament.  7,  7.  The  two  lateral  ligaments.  8,  8.  The  spnce  loft  un- 
covered by  the  peritoneum,  and  surrounded  by  the  coronary  ligament.  9.  Tlie  inferior 
vena  cava.  10.  The  point  of  the  lobus  Spigclii.  3.  The  fundus  of  the  gall-bladder 
seen  projecting  beyond  the  anterior  border  of  the  right  lobe. 


512  '    LIGAMENTS  OF  THE  LIVER. 

The  liver  is  retained  in  its  place  by  five  ligaments ;  four  of  which 
are  formed  by  duplicatures  of  the  peritoneum,  and  are  situated  upon 
the  convex  surface  of  the  organ;  the  fifth  being  a  fibrous  cord  which 
passes  through  a  fissure  in  its  under  surface,  from  the  umbilicus  to 
the  inferior  vena  cava.     They  are  the — 

Longitudinal, 
Two  lateral. 
Coronary, 
Round. 

The  Longitudinal  ligament  (broad,  ligamentum  suspensorium 
hepatis)  is  an  antero-posterior  fold  of  peritoneum,  extending  from 
the  notch  on  the  anterior  margin  of  the  liver  to  its  posterior  border. 
Between  its  two  layers  in  the  anterior  and  free  margin  is  the  round 
ligament. 

The  two  Lateral  ligaments  are  formed  by  the  two  layers  of  peri- 
toneum, which  pass  from  the  under  surface  of  the  diaphragm  to 
the  posterior  border  of  the  liver ;  they  correspond  with  its  lateral 
lobes. 

The  Coronary  ligament  is  formed  by  the  separation  of  the  two 
layers  forming  the  lateral  ligaments  near  their  point  of  convergence. 
The  posterior  layer  is  continued  unbroken  from  one  lateral  Hgament 
into  the  other ;  but  the  anterior  quits  the  posterior  at  each  side,  and 
is  continuous  with  the  corresponding  layer  of  the  longitudinal  liga- 
ment. In  this  way  a  large  oval  surface  on  the  posterior  border  of 
the  liver  is  left  uncovered  by  peritoneum,  and  is  connected  to  the 
diaphragm  by  a  dense  cellular  tissue.  This  space  is  formed  prin- 
cipally by  the  right  lateral  ligament,  and  is  pierced  near  its  left 
extremity  by  the  inferior  vena  cava,  previously  to  the  passage  of 
that  vessel  through  the  tendinous  opening  in  the  diaphragm. 

The  Round  ligament  is  a  fibrous  cord  resulting  from  the  oblitera- 
tion of  the  umbilical  vein,  and  situated  between  the  two  layers  of 
peritoneum  in  the  anterior  border  of  the  longitudinal  ligament.  It 
may  be  traced  from  the  umbilicus,  along  the  longitudinal  fissure 
upon  the  under  surface  of  the  liver  to  the  inferior  vena  cava  to  which 
it  is  connected. 

The  under  surface  of  the  liver  is  marked  by  five  fissures  which 
divide  its  surface  into  five  compartments  or  lobes,  two  principal  and 
three  minor  lobes  ;  they  are  the — 

Fissures.  Lobes. 

Longitudinal  fissure.  Right  lobe. 

Fissure  of  the  ductus  vcnosus.  Left  lobe. 

Transverse  fissure,  Lobus  quadratus, 

Fissure  for  the  gall-bladder,  Lobus  Spigelii, 

Fissure  for  the  vena  cava.  Lobus  caudatus. 


FISSURES  OP  THE  LIVER. 


513 


The  Longitudinal  fissure  is  a  deep  groove  running  from  the  notch 
upon  the  anterior  margin  of  the  liver,  to  the  posterior  border  of  the 
organ.  At  about  one  third  from  its  posterior  extremity  it  is  joined 
by  a  short  but  deep  fissure,  the  transverse,  which  meets  it  trans- 
versely from  the  under  part  of  the  right  lobe. 

Fig.  154.* 


The  longitudinal  fissure  in  front  of  this  junction  lodges  the  fibrous 
cord  of  the  umbilical  vein,  and  is  generally  crossed  by  a  band  of 
hepatic  substance  called  the  pons  hepatis. 

The  Fissure  for  the  ductus  venosus  is  the  shorter  portion  of  the 
longitudinal  fissure,  extending  from  the  junctional  termination  of 
the  transverse  fissure  to  the  posterior  border  of  the  liver,  and  con- 
taining a  small  fibrous  cord,  the  remains  of  the  ductus  venosus. 
This  fissure  is  therefore  but  a  part  of  the  longitudinal  fissure. 

The  Transverse  fissure  is  the  short  and  deep  fissure,  about  two 
inches  in  length,  through  which  the  hepatic  ducts,  hepatic  artery, 
and  portal  vein  enter  the  liver.  Hence  this  fissure  was  considered 
by  the  older  anatomists  as  the  gate  (porta)  of  the  liver ;  and  the 
large  vein  entering  the  organ  at  this  point,  the  portal  vein.  At  their 
entrance  into  the  transverse  fissure  the  branches  of  the  hepatic  duct 
are  the  most  anterior,  next  those  of  the  artery,  and  most  posteriorly 
the  portal  vein. 

*  The  under  surface  of  the  liver.  1.  The  rig-ht  lobe.  2.  The  left  lobe.  3.  The  lobus 
quadratus.  4.  The  lobus  Spigelii.  5.  Tlio  lobus  caudatus.  6.  The  longitudinal  fis- 
sure, in  which  is  seen  the  rounded  cord  ;  the  remains  of  the  umbilical  vein.  7.  The 
pons  hepatis.  8.  The  fissure  for  the  ductus  venosus  ;  the  obliterated  cord  of  the  ductus 
is  seen  passing  backwards  to  be  attached  to  the  coats  of  tlie  inferior  vena  cava  9.  10. 
The  gall-bladder  lodged  in  its  fossa.  11.  The  transverse  fissure,  containing  from  before 
backwards,  the  hepatic  duct,  hepatic  artery,  and  portal  vein.  12.  The  vena  cava.  13. 
A  depression  corresponding  with  the  curve  of  the  colon.  14.  A  double  depression  pro- 
duced by  the  right  kidney  and  its  supra-renal  capsule.  15.  The  rough  surface  on  the 
posterior  border  of  the  liver  left  uncovered  by  peritoneum  ;  the  cut  edge  of  peritoneum 
surrounding  this  surface  forms  part  of  the  coronary  ligament.  16.  The  notch  on  the 
anterior  border,  separating  the  two  lobes.  17.  The  notch  on  the  posterior  border,  cor- 
responding with  the  vertebral  column. 

G5 


514  LOBES  OF  THE  LIVER. 

The  Fissure  for  the  gall-bladder  is  a  shallow  fossa  extending  for- 
wards, parallel  with  the  longitudinal  fissure,  from  the  right  extre- 
mity of  the  transverse  fissure  to  the  free  border  of  the  liver,  where 
it  frequently  forms  a  notch. 

The  Fissure  for  the  vena  cava  is  a  deep  and  short  fissure  occa- 
sionally a  rounded  tunnel,  which  proceeds  from  a  little  behind  the 
right  extremity  of  the  transverse  fissure  to  the  posterior  border  of 
the  liver,  and  lodges  the  inferior  vena  cava. 

These  five  fissures  taken  collectively  resemble  an  inverted  y, 
the  base  corresponding  with  the  free  margin  of  the  liver,  and  the 
apex  with  its  posterior  border.  Viewing  them  in  this  way,  the  two 
anterior  branches  represent  the  longitudinal  fissure  on  the  left,  and 
the  fissure  for  the  gall-bladder  on  the  right  side ;  the  two  posterior, 
the  fissure  for  the  ductus  venosus  on  the  left,  and  the  fissure  for  the 
vena  cava  on  the  right  side,  and  the  connecting  bar  the  transverse 
fissure. 

Lobes. — The  Right  lobe  is  four  or  six  times  larger  than  the  left, 
from  which  it  is  separated  on  the  concave  surface  by  the  longitu- 
dinal fissure,  and  on  the  convex  by  the  longitudinal  ligament.  It  is 
marked  upon  its  under  surface  by  the  transverse  fissure,  and  by  the 
fissures  for  the  gall-bladder  and  vena  cava,  and  presents  three 
depressions,  one  in  front  for  the  curve  of  the  ascending  colon,  and 
two  behind  for  the  right  supra-renal  capsule,  and  kidney. 

The  Left  lobe  is  small  and  flattened,  convex  upon  its  upper  sur- 
face, and  concave  below,  where  it  lies  in  contact  with  the  anterior 
surface  of  the  stomach.  It  is  sometimes  in  contact  by  its  extre- 
mity with  the  upper  end  of  the  spleen,  and  is  in  relation  by  its  pos- 
terior border  with  the  cardiac  orifice  of  the  stomach,  and  left  pneu- 
mogastric  nerve. 

The  lobus  quadratus  is  a  quadrilateral  lobe  situated  upon  the 
under  surface  of  the  right  lobe :  it  is  bounded  in  front  by  the  free 
border  of  the  liver ;  behind  by  the  transverse  fissure ;  to  the  right 
by  the  gall-bladder ;  and  to  the  left  by  the  longitudinal  fissure. 

The  Lobus  Spigelii*  is  a  small  triangular  lobe,  also  situated  upon 
the  under  surface  of  the  right  lobe :  it  is  bounded  in  front  by  the 
transverse  fissure ;  and  on  the  sides  by  the  fissures  for  the  ductus 
venosus  and  vena  cava. 

The  Lobus  caudatus  is  a  small  tail-like  appendage  to  the  lobus 
Spigelii,  from  which  it  runs  outwards  like  a  crest  into  the  right 
lobe,  and  serves  to  separate  the  right  extremity  of  the  transverse 
fissure  from  the  commencement  of  the  fissure  for  the  vena  cava.  In 
some  livers  this  lobe  is  extremely  well-marked,  in  others  it  is  small 
and  ill-defined. 

Reverting  to  the  comparison  of  the  fissures  with  an  inverted  y,  it 

*  Adrian  Spijrcl,  a  I3c]gian  physician,  professor  at  Padua  after  Casscrius  in  1616. 
IT(!  assi;[rn(;d  considerable  importance  to  tliis  little  lobe,  but  it  had  been  described  by 
Sylvius  full  sixty  yours  before  his  time. 


STRUCTURE  OF  THE  LIVER,  515 

will  be  observed  that  the  quadrilateral  interval,  in  front  of  the  trans- 
verse bar,  represents  the  lobus  quadratus;  the  triangular  space 
behind  the  bar,  represents  the  Spigelii ;  and  the  apex  of  the  letter, 
the  point  of  union  between  the  inferior  vena  cava,  and  the  remains 
of  the  ductus  venosus. 

The  Vessels  entering  into  the  structure  of  the  liver  are  also  Jive  in 
number';  they  are,  the 

Hepatic  artery, 
Portal  vein. 
Hepatic  veins. 
Hepatic  ducts. 
Lymphatics. 

The  Hepatic  artery,  portal  vein,  and  hepatic  duct  enter  the  liver 
at  the  transverse  fissure,  and  ramify  through  portal  canals  to  every 
part  of  the  organ ;  so  that  their  general  direction  is  from  below 
upwards,  and  from  the  centre  towards  the  circumference. 

The  Hepatic  veins  commence  at  the  circumference  and  proceed 
from  before  backwards,  to  open  into  the  vena  cava,  on  the  posterior 
border  of  the  hver.  Hence  the  branches  of  the  two  veins  cross  each 
other  in  their  course. 

The  portal  vein,  hepatic  artery,  and  duct  are  moreover  enveloped 
in  a  loose  cellular  tissue,  the  capsule  of  Glisson,  which  permits  them 
to  contract  upon  themselves  when  emptied  of  their  contents ;  the 
hepatic  veins,  on  the  contrary,  are  closely  adherent  by  their  parietes 
to  the  surface  of  the  canals  in  which  they  run,  and  are  unable  to 
contract.  By  these  characters  the  anatomist  is  enabled,  in  any  sec- 
tion of  the  liver,  to  distinguish  at  once  the  most  minute  branch  of 
the  portal  vein  from  the  hepatic  vein;  the  former  will  be  found  more 
or  less  collapsed,  and  always  accompanied  by  an  artery  and  duct, 
and  the  latter  widely  open  and  solitary. 

The  Lymphatics  are  described  in  the  Chapter  dedicated  to  those 
vessels. 

The  JVerves  of  the  liver  are  derived  from  the  systems  both  of 
animal  and  of  organic  hfe;  the  former  proceed  from  the  right 
phrenic  and  pneumogastric  nerves,  and  the  latter  from  the  hepatic 
plexus. 

Structure  and  Minute  Anatomy  of  the  Liver,  according  to  Mr. 

Kiernan. 

The  Liver  is  composed  of  lobules,  of  a  connecting  medium,  called 
Glisson' s  capsule,  of  the  ramifications  of  the  portal  vein,  hepatic  duct, 
hepatic  artery,  hepatic  veins,  lymphatics,  and  nerves,  and  is  enclosed 
and  retained  in  its  proper  situation  by  the  peritoneum.  I  shall 
describe  each  of  these  structures  singly,  following  rigidly  the  dis- 
coveries of  Mr.  Kiernan. 


516 


LOBULES  OF  THE  LIVER. 


1.  The  Lobules  are  small  granular  bodies,  of  about  the  size  of  a 
millet  seed,  of  an  irregular  form,  and  presenting  a  number  of 
rounded  projecting  processes  upon  their  surface.  When  divided 
longitudinally,  they  have  a  foliated  appearance;,  and  transversely,  a 
polygonal  outline,  with  sharp  or  rounded  angles,  according  to  the 
smaller  or  greater  quantity  of  Glisson's  capsule  contained  in  the 
liver.  Each  lobule  is  divided  upon  its  exterior  into  a  base  and  a 
capsular  surface.  The  base  corresponds  with  one  extremity  of  the 
lobule,  is  flattened,  and  rests  upon  an  •  hepatic  vein,  which  is  thence 
named  sublobular.  The  capsular  surface  includes  the  rest  of  the 
periphery  of  the  lobule,  and  has  received  its  designation  from  being 
enclosed  in  a  cellular  capsule  derived  from  the  capsule  of  Glisson. 
In  the  centre  of  each  lobule  is  a  small  vein,  the  intralobular,  which 
is  formed  by  the  convergence  of  six  or  eight  minute  venules  from 
the  rounded  processes  situated  upon  the  surface.  The  intralobular 
vein  thus  constituted  takes  its  course  through  the  centre  of  the  lon- 
gitudinal axis  of  the  lobule,  pierces  the  middle  of  its  base,  and 
opens  into  the  sublobular  vein.  The  circumference  of  the  lobule, 
with  the  exception  of  its  base,  which  is  always  closely  attached  to 
a  sublobular  vein,  is  connected  by  means  of  its  cellular  capsule  with 
the  capsular  surface  of  surrounding  lobules.  The  cellular  interval 
between  the  lobules  is  the  interlobular  fissure,  and  the  angular  inter- 
stices formed  by  the  apposition  of  several  lobules  are  the  interlobular 
spaces. 

Fiff.  155.* 


The  lobules  of  the  centre  of  the  liver  are  angular,  and  somewhat 
smaller  than  those  of  the  surface,  from  the  greater  compression  to 
which  they  arc  submitted.  The  superficial  lobules  are  incomplete, 
and  give  to  the  surface  of  the  organ  the  appearance,  and  all  the 
advantages  resulting  from  an  examination  of  a  transverse  section. 


*  The  lobules  of  the  liver.  A.  The  lobules  as  they  arc  seen  upon  the  surface  of  the 
liver,  or  whnn  divided  transversely.  ] .  The  intralobular  vein  in  the  eentre  of  each 
lobule.  2.  The  interlobular  fissure.  3.  Tlie  interlobular  si)aeo.  B.  A  longitudinal 
section  of  two  lol)u]es.  1.  A  superficial  lobule,  tci  iniiiating-  abruptly,  and  resembling 
a  section  at  its  exiremity.  9.  A  deep  lobule,  showing  the  foliated  appearance  of  its 
section.  3.  The  intralobular  vein,  with  its  converging  venules  ;  the  vein  terminates  in 
a  sublobular  vein.     4.  The  external,  or  capsular  surface  of  the  lobule. 


GLISSOn's  capsule PORTAL  VEIN.  517 

"  Each  lobule  is  composed  of  a  plexus  of  biliary  ducts,  of  a  venous 
plexus  formed  by  branches  of  the  portal  vein,  of  a  branch  (intra- 
lobular), of  an  hepatic  vein,  and  of  minute  arteries ;  nerves  and 
absorbents,  it  is  to  be  presumed,  also  enter  into  their  formation,  but 
cannot  be  traced  into  them."  "  Examined  with  the  microscope,  a 
lobule  is  apparently  composed  of  numerous  minute  bodies  of  a  yel- 
lowish colour,  and  of  various  forms,  connected  with  each  other  by 
vessels.  These  minute  bodies  are  the  acini  of  Malpighi."  "  If  an 
uninjected  lobule  be  examined  and  contrasted  with  an  injected 
lobule,  it  will  be  found  that  the  acini  of  Malpighi  in  the  former 
are  identical  with  the  injected  lobular  biliary  plexus  in  the  latter, 
and  the  blood-vessels  in  both  will  be  easily  distinguished  from  the 
ducts." 

Glisson's  capsule  is  the  cellular  tissue  which  envelopes  the  hepatic 
artery,  portal  vein,  and  hepatic  duct,  during  their  passage  through 
the  right  border  of  the  lesser  omentum,  and  which  continues  to 
surround  them  to  their  ultimate  distribution  in  the  substance  of  the 
lobules.  It  forms  for  each  lobule  a  distinct  capsule,  which  invests 
it  on  all  sides  with  the  exception  of  its  base,  connects  all  the  lobules 
together,  and  constitutes  the  proper  capsule  of  the  entire  organ.  But 
"  Glisson's  capsule,"  observes  Mr.  Kaernan,  "  is  not  mere  cellular 
tissue  ;  it  is  to  the  liver  what  the  pia  mater  is  to  the  brain ;  it  is  a 
cellulo-vascular  membrane  in  which  the  vessels  divide  and  subdivide 
to  an  extreme  degree  of  minuteness ;  which  Imes  the  portal  canals, 
forming  sheaths  for  the  larger  vessels  contained  in  them,  and  a  web 
in  which  the  smaller  vessels  ramify  ;  which  enters  the  interlobular 
fissures,  and  with  the  vessels  forms  the  capsules  of  the  lobules  ;  and 
which  finally  enters  the  lobules,  and  with  the  blood-vessels  expands 
itself  over  the  secreting  biliaiy  ducts."  Hence  arises  a  natural 
division  of  the  capsule  into  three  portions,  a  vaginal,  an  interlobula?; 
and  a  lobular  portion. 

The  vaginal  portion  is  that  which  invests  the  hepatic  artery, 
hepatic  duct,  and  portal  vein,  in  the  portal  canals ;  in  the  larger 
canals  it  completely  surrounds  these  vessels,  but  in  the  smaller  is 
situated  only  on  that  side  which  is  occupied  by  the  artery  and  duct. 
The  interlobular  portion  occupies  the  interlobular  fissures  and  spaces, 
and  the  lobular  portion  forms  the  supporting  tissue  to  the  substance 
of  the  lobules. 

The  Portal  vein,  entering  the  liver  at  the  transverse  fissure,  rami- 
fies through  its  structure  in  canals  which  resemble,  by  their  surfaces, 
the  external  superficies  of  the  liver,  and  are  formed  by  the  capsular 
surfaces  of  the  lobules, — "  all  their  canals  being,"  as  it  were,  "  tubu- 
lar inflections  inwards  of  the  superficies  of  the  liver."  These  are 
the  portal  canals,  and  contain,  besides  the  portal  vein  with  its  rami- 
fications, the  artery  and  duct  with  their  branches. 

In  the  larger  canals,  the  vessels  are  separated  from  the  parietes 
of  the  cavity  by  a  web  of  Glisson's  capsule ;  but,  in  the  smaller,  the 
portal  vein  is  in  contact  with  the  surface  of  the  canal  for  about  two- 


518  STRUCTURAL  ANATOHY  OF  THE  LIVER. 

thirds  of  its  cylinder,  the  opposite  third  being  in  relation  with  the 
artery  and  duct  and  their  investing  capsule.  If,  therefore,  the  portal 
v.ein  were  laid  open  by  a  longitudinal  incision  in  one  of  these  smaller 
canals,,  the  coats  being  transparent,  the  outline  of  the  lobules,  bounded 
by  their  interlobular  fissures,  would  be  as  distinctly  seen  as  upon 
the  external  surface  of  the  liver,  and  the  smaller  venous  branches 
would  be  observed  entering  the  interlobular  spaces. 

The  branches  of  the  portal  vein  are,  the  vaginal,  interlobular,  and 
lobular.  The  vaginal  branches  are  those  which,  being  given  off  in 
the  portal  canals,  have  to  pass  through  the  sheath  (vagina)  of  GUs- 
son's  capsule,  previously  to  entering  the  interlobular  spaces.  In 
this  course  they  form  an  intricate  plexus,  the  vaginal  plexus,  which, 
depending  for  its  existence  on  the  capsule  of  Glisson,  necessarily 
surrounds  the  vessels,  as  does  that  capsule  in  the  larger  canals,  and 
occupies  the  capsular  side  only  in  the  smaller  canals.  The  interlo- 
bular branches  are  given  off  from  the  vaginal  portal  plexus  where 
it  exists,  and  directly  from  the  portal  veins,  in  that  part  of  the 
smaller  canals  where  the  coats  of  the  vein  are  in  contact  with  the 
walls  of  the  canal.  They  then  enter  the  interlobular  spaces  and 
divide  into  branches,  which  cover  with  their  ramifications  every 
part  of  the  surface  of  the  lobules  with  the  exception  of  their  bases, 
and  those  extremities  of  the  superficial  lobules  which  appear  upon 
the  surfaces  of  the  liver.  The  interlobular  veins  communicate 
freely  with  each  other,  and  with  the  corresponding  veins  of  adjoin- 
ing fissures,  and  establish  a  general  portal  anastomosis  throughout 
the  entire  liver.  The  lobular  branches  are  derived  from  the  interlo- 
bular veins ;  they  form  a  plexus  within  each  lobule,  and  converge 
from  the  circumference  towards  the  centre,  where  they  terminate 
in  the  minute  radicles  of  the  intralobular  portal  vein.  This  plexus, 
interposed  between  the  interlobular  portal  veins  and  the  intralobular 
hepatic  vein,  constitutes  the  venous  part  of  the  lobule,  and  may  be 
called  the  lobular  venous  plexus.  The  irregular  islets  of  the  substance 
of  the  lobules,  seen  between  the  meshes  of  this  plexus  by  means  of 
the  microscope,  are  the  acini  of  Malpighi,  and  are  shown  by  Mr. 
Kiernan  to  be  portions  of  the  lobular  biliary  plexus. 

The  portal  vein  returns  the  venous  blood  from  the  chylopoietic 
viscera,  to  be  circulated  through  the  lobules ;  it  also  receives  the 
venous  blood  which  results  from  the  distribution  of  the  hepatic  artery. 

The  Hepatic  duct,  entering  the  liver  at  the  transverse  fissure, 
divides  into  branches,  which  ramify  through  the  portal  canals,  with 
the  portal  vein  and  hepatic  artery,  to  terminate  in  the  substance  of 
the  lobules.  Its  branches,  like  those  of  the  portal  vein,  are  vaginal, 
interlobular,  and  lobular. 

The  Vaginal  branches  ramify  through  the  capsule  of  Glisson,  and 
form  a  vaginal  biliary  plexus,  which,  like  the  vaginal  portal  plexus, 
surrounds  the  vessels  in  the  large  canals,  but  is  deficient  on  that  side 
of  the  smaller  canals  near  which  the  duct  is  placed.  The  branches 
given  off  by  the  vaginal  biliary  plexus  are  interlobular  and  lobular. 


KIERNAN  S  RESEARCHES.  519 

The  interlobular  branches  proceed  from  the  vaginal  bUiary  plexus 
where  it  exists,  and  directly  from  the  hepatic  duct  on  that  side  of 
the  smaller  canals  against  which  the  duct  is  placed.  They  enter 
the  interlobular  spaces,  and  ramify  upon  the  capsular  surface  of  the 
lobules,  in  the  interlobular  fissures,  where  they  communicate  freely 
Avith  each  other.  The  lobular  ducts  are  derived  chiefly  from  the 
interlobular;  but  to  those  lobules  forming  the  walls  of  the  portal 
canals,  they  pass  directly  from  the  vaginal  plexus.  They  enter  the 
lobule  and  form  a  plexus  in  its  interior,  the  lobular  biliary  plexus, 
which  constitutes  the  principal  part  of  the  substance  of  the  lobule. 
The  ducts  terminate  either  in  loops  or  in  cjecal  extremities. 

The  coats  of  the  ducts  are  very  vascular,  and  supplied  with  a 
number  of  mucous  follicles,  which  are  distributed  irregularly  in  the 
larger,  but  are  arranged  in  two  parallel  longitudinal  rows  in  the 
smaller  ducts. 

The  Hepatic  artery  enters  the  liver  with  the  portal  vein  and 
hepatic  duct,  and  ramifies  with  those  vessels  through  the  portal 
canals.  Its  branches  are  the  vaginal,  interlobular,  and  lobular.  The 
vaginal  branches,  like  those  of  the  portal  vein  and  hepatic  duct, 
form  a  vaginal  plexus,  which  exists  throughout  the  whole  extent  of 
the  portal  canals,  with  the  exception  of  that  side  of  the  smaller 
canals  which  corresponds  with  the  artery.  The  interlobular  branches, 
arising  from  the  vaginal  plexus  and  from  the  parietal  side  of  the 
artery  in  the  smaller  canals,  ramify  through  the  interlobular  fis- 
sures, and  are  principally  distributed  to  the  coats  of  the  interlobular 
ducts. 

"  From  the  superficial  interlobular  fissures  small  arteries  emerge, 
and  ramify  in  the  proper  capsule,  on  the  convex  and  concave  surface 
of  the  liver,  and  in  the  hgaments.  These  are  the  capsular  arteries" 
Where  the  capsule  is  well  developed,  "  these  vessels  cover  the  sur- 
faces of  the  liver  with  a  beautiful  plexus,"  and  "  anastomose  with 
branches  of  the  phrenic,  internal  mammary,  and  supra-renal  arte- 
ries," and  with  the  epigastric. 

The  Lobular  branches,  extremely  minute  and  few  in  number,  are 
the  nutrient  vessels  of  the  lobules,  and  terminate  in  the  lobular 
venous  plexus. 

All  the  venous  blood  resulting  from  the  distribution  of  the  hepatic 
artery,  even  that  from  the  vasa  vasorum  of  the  hepatic  veins,  is 
returned  into  the  portal  vein. 

The  Hepatic  veins  commence  in  the  substance  of  each  lobule  by 
minute  venules,  which  receive  the  blood  from  the  lobular  venous 
plexus,  and  converge  to  form  the  intralobular  vein.  The  intralobular 
vein  passes  through  the  central  axis  of  the  lobule,  and  through  the 
middle  of  its  base,  to  terminate  in  a  sublobular  vein ;  and  the  union 
of  the  sublobular  veins  constitutes  the  hepatic  trunks,  which  termi- 
nate in  the  inferior  vena  cava.  The  hepatic  venous  system  consists, 
therefore,  of  three  sets  of  vessels ;  intralobular  veins,  sublobular 
veins,  and  hepatic  trunks. 


520  STRUCTUEAL  ANATOMY  OF  THE  LIVER, 

The  SuhlohuJar  veins  are  contained  in  canals  formed  solely  by  the 
bases  of  the  lobules,  with  which,  from  the  absence  of  Ghsson's  cap- 
sule, they  are  in  immediate  contact.  Their  coats  are  thin  and  trans- 
parent ;  and,  if  they  be  laid  open  by  a  longitudinal  incision,  the 
bases  of  the  lobules  will  be  distinctly  seen,  separated  by  interlobular 
fissures,  and  perforated  through  the  centre  by  the  opening  of  the 
intralobular  vein. 

The  Hepatic  trunks  are  formed  by  the  union  of  the  sublobular 
veins;  they  are  contained  in  canals  (hepatic  venous)  similar  in 
structure  to  the  portal  canals,  and  lined  by  a  prolongation  of  the 
proper  capsule.  They  proceed  from  before  backwards,  and  termi- 
nate by  two  large  openings,  corresponding  to  the  right  and  left  lobe 
of  the  liver  in  the  inferior  vena  cava. 

It  is  to  Kiernan  that  anatomical  science  is  indebted  for  the  clear, 
distinct,  and  intelligible  idea  of  the  structure  of  this  most  compli- 
cated organ,  which  has  been  furnished  by  the  researches  of  that 
anatomist.  To  value  this  knowledge  as  it  deserves,  we  have  but  to 
reflect  upon  the  unsuccessful,  though  not  fruitless,  labours  of  those 
great  discoverers  in  structural  anatomy,  Malpighi  and  Ruysch,  upon 
the  same  subject,  and  the  strange  misconceptions  of  modern  authors, 
among  whom  Miiller  and  Cruveilhier  occupy  so  conspicuous  a  place. 
It  is  not,  however,  in  an  anatomical,  or  even  a  physiological  point 
of  view  merely,  that  we  have  to  admii^e  these  discoveries  ;  for  in 
their  practical  application  to  the  elucidation  of  pathological  appear- 
ances, and  the  explanation  of  the  phenomena  of  disease,  they  are 
still  more  interesting. 

Summary. — The  liver  has  been  shown  to  be  composed  of  lobules  ; 
the  lobules  (excepting  at  their  bases)  are  invested  and  connected 
together,  the  vessels  supported,  and  the  whole  organ  enclosed  by 
Glisson's  capsule ;  and  they  are  so  arranged,  that  the  base  of  every 
lobule  in  the  liver  is  in  contact  with  an  hepatic  vein  (sublobular). 

The  Portal  vein  distributes  its  numberless  branches  through  portal 
canals,  which  are  channeled  through  every  part  of  the  organ ;  it 
brings  the  returning  blood  from  the  chylopoietic  viscera  ;  it  collects 
also  the  venous  blood  from  the  ultimate  ramifications  of  the  hepatic 
artery  in  the  liver  itself.  It  gives  oft"  branches  in  the  canals,  which 
are  called  vaginal,  and  form  a  venous  vaginal  plexus;  these  give 
off'  interlobular  branches,  and  the  latter  enter  the  lobules  and  form 
lobular  venous  plexuses,  from  the  blood  circulating  in  which  the  bile 
is  secreted. 

The  Bile  in  the  lobule  is  received  by  a  network  of  minute  ducts, 
the  lobular  biliary  plexus ;  it  is  conveyed  from  the  lobule  into  the 
interlobular  ducts ;  it  is  thence  poured  into  the  biliary  vaginal  plexus 
of  the  portal  canals,  and  thence  into  the  excreting  ducts,  by  which 
it  is  carried  to  the  duodenum  and  gall-bladder,  after  being  mingled 
in  its  course  with  the  mucous  secretion  from  the  numberless  muci- 
parous follicles  in  the  walls  of  the  ducts. 

The  Hepatic  artery  distributes  branches  through  every  portal 
canal;  gives  cM  vaginal  branches  wliicli  form  a  vaginal  hepatic 


STRUCTURAL  ANATOMY  OF  THE  LIVER.  521 

plexus,  from  which  the  interlobular  branches  arise,  and  these  latter 
terminate  ultimately  in  the  lobular  venous  plexuses  of  the  portal 
vein.  The  artery  ramifies  abundantly  in  the  coats  of  the  hepatic 
ducts,  enabhng  them  to  provide  their  mucous  secretion ;  and  sup- 
plies the  vasa  vasorum  of  the  portal  and  hepatic  veins,  and  the  nu- 
trient vessels  of  the  entire  organ. 

The  Hepatic  veins  commence  in  the  centre  of  each  lobule  by 
minute  radicles,  which  collect  the  impure  blood  from  the  lobular 
venous  plexus  and  convey  it  into  the  intralobular  veins ;  these  open 
into  the  sublohular  veins,  and  the  sublobular  veins  unite  to  form  the 
large  hepatic  trunks  by  which  the  blood  is  conveyed  into  the  vena 
cava. 

The  physiological  deduction  arising  out  of  this  anatomical  ar- 
rangement is,  that  the  bile  is  loholly  secreted  from  venous  blood,  and 
not  from  a  mixed  venous  and  arterial  blood,  as  is  believed  by 
MiJller ;  for  although  the  portal  vein  receives  its  blood  from  two 
sources,  viz.  from  the  chylopoietic  viscera  and  from  the  capillaries 
of  the  hepatic  artery,  yet  the  very  fact  of  the  blood  of  the  latter  ves- 
sel having  passed  through  its  capillaries  into  the  portal  vein,  or  in 
extremely  small  quantity  into  the  capillary  network  of  the  lobular 
venous  plexus,  is  sufficient  to  establish  its  venous  character.* 

The  pathological  deductions  depend  upon  the  following  facts  : — 
Each  lobule  is  a  perfect  gland  ;  of  uniform  structure,  of  uniform 
colour,  and  possessing  the  same  degree  of  vascularity  throughout. 
It  is  the  seat  of  a  double  venous  circulation,  the  vessels  of  the  one 
{hepatic)  being  situated  in  the  centre  of  the  lobule,  and  those  of  the 
other  {portal)  in  the  circumference.  Now  the  colour  of  the  lobule, 
as  of  the  entire  hver,  depends  chiefly  upon  the  proportion  of  blood 
contained  within  these  two  sets  of  vessels  ;  and  so  long  as  the  cir- 
culation is  natural  the  colour  will  be  uniform.  But  the  instant  that 
any  cause  is  developed  which  shall  interfere  with  the  free  circula- 
tion of  either,  there  will  be  an  immediate  diversity  in  the  colour  of 
the  lobule. 

Thus,  if  there  be  any  impediment  to  the  free  circulation  of  the 
venous  blood  through  the  heart  or  lungs,  the  circulation  in  the 
hepatic  veins  will  be  retarded,  and  the  sublobular  and  the  intra- 
lobular veins  will  become  congested,  giving  rise  to  a  more  or  less 
extensive  redness  in  the  centre  of  each  of  the  lobules,  while  the  mar- 
ginal or  non-congested  portion  presents  a  distinct  border  of  a  yel- 
lowish white,  yellow,  or  green  colour,  according  to  the  quantity 
and  quality  of  the  bile  it  may  contain.  *'  This  is  'passive  congestion' 
of  the  liver,  the  usual  and  natural  state  of  the  organ  after  death  ;" 
and,  as  it  commences  with  the  hepatic  vein,  it  may  be  called  the 
first  stage  of  hepatic-venous  congestion. 

But  if  the  causes  which  produced  this  state  of  congestion  con- 
tinue, or  be  from  the  beginning  of  a  more  active  kind,  the  conges- 

*  For  argumenis  upon  this  contested  question,  see  the  article  "  Liver,"  in  the  "  Cyclo- 
paedia of  Anatomy  and  Physiology,"  edited  by  Dr.  Todd. 

6l> 


522  GALL-RLADDEU. 

tion  will  extend  through  the  lobular  venous  plexuses  "into  those 
branches  of  the  portal  vein  situated  in  the  interlohidar  -fissures,  but 
not  to  those  in  the  spaces,  which,  being  larger,  and  giving  origin  to 
those  in  the  fissures,  are  the  last  to  be  congested."  In  this  second 
stage  the  liver  has  a  mottled  appearance,  the  non-congested  sub- 
stance is  arranged  in  isolated,  circular,  and  ramose  patches,  in  the 
centres  of  which  the  spaces  and  part  of  the  fissures  are  seen.  This 
is  an  extended  degree  of  hepatic-venous  congestion ;  it  is  "  active 
congestion^'  of  the  liver,  and  very  commonly  attends  diseases  of  the 
heart  and  lungs. 

There  is  another  form  of  partial  venous  congestion  which  com- 
mences in  the  portal  vein;  this  is,  therefore,  portal  venous  congestion. 
It  is  of  very  rare  occurrence,  and  Mr.  Kiernan  has  observed  it  in 
children  only.  "  In  this  form  the  congested  substance  never  assumes 
the  deep  red  colour  which  characterizes  hepatic  venous  conges- 
tion; the  interlobular  fissures  and  spaces,  and  the  marginal  portions 
of  the  lobules  are  of  a  deeper  colour  than  usual ;  the  congested 
substance  is  continuous  and  cortical,  the  non-congested  substance 
being  medullary,  and  occupying  the  centres  of  the  lobules.  The 
second  stage  of  hepatic- venous  congestion,  in  which  the  congested 
substance  appears,  but  is  not  cortical,  may  be  easily  confounded 
with  portal  venous  congestion. 

These  are  instances  of  partial  congestion,  but  there  is  sometimes 
general  congestion  of  the  organ.  "  In  general  congestion  the  whole 
liver  is  of  a  red  colour,  but  the  central  portions  of  the  lobules  are 
usually  of  a  deeper  hue  than  the  marginal  portions." 

GALL-BLADDER. 

The  gall-bladder  is  the  reservoir  for  the  bile ;  it  is  a  pyriform  sac 
situated  in  a  fossa,  upon  the  under  surface  of  the  right  lobe  of  the 
liver,  and  extending  from  the  right  extremity  of  the  transverse  fis- 
sure to  its  free  margin.  It  is  divided  into  a  body,  fundus,  and  neck ; 
the  fundus  or  broad  extremity  in  the  natural  position  of  the  fiver  is 
placed  downwards,  and  frequently  projects  beyond  the  free  margin 
of  the  fiver,  while  the  neck,  small  and  constricted,  is  directed 
upwards.  This  sac  is  composed  of  three  coats,  serous,  fibrous,  and 
mucous.  The  serous  coat  is  partial,  is  derived  from  the  peritoneum, 
and  covers  that  side  only  which  is  unattached  to  the  liver.  The 
middle  oy  fibrous  coat  is  a  thin  but  strong  cellulo-fibrous  layer,  inter- 
mingled with  tendinous  fibres.  It  is  connected  on  one  side  to  the 
liver,  and  on  the  other  to  the  peritoneum.  The  internal  or  mucous 
coat  is  but  loosely  connected  with  the  fibrous  layer;  it  is  every 
where  raised  into  minute  ruga3  which  give  it  a  beautifully  reticu- 
lated appearance,  and  forms  at  the  neck  of  the  sac  a  spiral  valve. 

It  is  continuous  through  the  hepatic  duct  with  the  mucous  mem- 
brane lining  all  the  ducts  of  the  liver,  and  through  the  ductus  com- 
munis choledochus,  with  the  mucous  membrane  of  the  alimentary 
canal. 


THE  PANCREAS.  .  523 

The  Biliary  ducts  are, — the  ductus  communis  choledochus,  the 
cystic  and  the  hepatic  duct. 

The  Ductus  communis  choledochus  (xoX^i  bihs,  Six^i^at  recipio)  is 
the  common  excretory  duct  of  the  Kver  and  gall-bladder;  it  is  about 
three  inches  in  length,  and  commences  upon  the  papilla,  situated  on 
the  inner  side  of  the  cylinder  of  the  perpendicular  portion  of  the 
duodenum.  Passing  obliquely  between  the  mucous  and  muscular 
coats,  it  ascends  behind  the  duodenum,  and  through  the  right  border 
of  the  lesser  omentum ;  and  divides  into  two  branches,  the  cystic 
duct  and  the  hepatic  duct.  It  is  constricted  at  its  commencement 
in  the  duodenum,  and  becomes  dilated  in  its  progress  upwards. 

The  Cystic  duct,  about  an  inch  in  length,  passes  outwards  to  the 
neck  of  the  gall-bladder,  with  which  it  is  continuous. 

The  Hepatic  duct  continues  onwards  to  the  transverse  fissure  of 
the  liver,  and  divides  into  two  branches,  which  ramify  through  the 
portal  canals  to  every  part  of  the  liver. 

The  coats  of  the  hepatic  ducts  are  an  external  or  fibrous,  and  an 
internal  or  mucous. 

The  external  coat  is  composed  of  a  contractile  fibrous  tissue, 
which  is  probably  muscular  ;  but  its  muscularity  has  not  yet  been 
demonstrated  in  the  human  subject.  The  mucous  coat  is  continuous 
on  the  one  hand  with  the  lining  membrane  of  the  hepatic  ducts  and 
gall-bladder,  and  on  the  other  with  that  of  the  duodenum. 

Vessels  and  JVerves. — The  gall-bladder  is  supplied  with  blood  by 
the  cystic  artery,  a  branch  of  the  hepatic.  Its  veins  return  their 
blood  into  the  portal  vein.  The  nerves  are  derived  from  the  hepatic 
plexus. 

THE  PANCREAS. 

The  Pancreas  is  a  long,  flattened,  conglomerate  gland,  analogous 
to  the  salivary  glands.  It  is  about  six  inches  in  length,  and  between 
three  or  four  ounces  in  weight,  and  is  situated  transversely  across 
the  posterior  wall  of  the  abdomen,  behind  the  stomach,  and  resting 
upon  the  aorta,  vena  portee,  inferior  vena  cava,  the  origin  of  the 
superior  mesenteric  artery,  and  the  left  kidney  and  supra-renal 
capsule ;  opposite  to  the  first  and  second  lumbar  vertebras.  It  is 
divided  into  a  body,  a  greater,  and  a  smaller  extremity ;  the  great 
end  or  head  is  placed  towards  the  right,  and  is  surrounded  by  the 
curve  of  the  duodenum ;  the  lesser  end  extends  to  the  left  as  far  as 
the  spleen.  The  anterior  surface  of  the  body  of  the  pancreas  is 
covered  by  the  ascending  posterior  layer  of  the  peritoneum  and  is 
in  relation  with  the  stomach,  the  first  portion  of  the  duodenum  and 
the  commencement  of  the  transverse  arch  of  the  colon.  The  pos- 
terior surface  is  grooved  for  the  splenic  vein,  and  tunneled  by  a 
complete  canal  for  the  superior  mesenteric  and  portal  vein,  and 
for  the  superior  mesenteric  artery.  The  upper  border  presents  a 
deep  groove,  sometimes  a  canal  for  the  splenic  artery  and  vein, 
and  is  in  relation  with  the  oblique  portion  of  the  duodenum,  the 


524  THE  SPLEEN. 

lobus  Spigelii,  and  the  coeliac  axis.  And  the  lower  border  is  sepa- 
rated from  the  transverse  portion  of  the  duodenum  by  the  superior 
roesenteric  artery  and  vein.  Upon  the  posterior  part  of  the  head 
of  the  .pancreas  is  a  lobular  fold  of  the  gland  which  completes  the 
canal  of  the  superior  mesenteric  vessels,  and  is  called  the  lesser  pan- 
creas. 

In  structure  it  is  composed  of  reddish-yellow  angular  lobules ; 
these  consist  of  smaller  lobules,  and  the  latter  are  made  up  of  the 
arborescent  ramifications  of  minute  ducts,  terminating  in  csecal 
pouches. 

The  pancreatic  duct  commences  at  the  papilla  upon  the  inner  and 
posterior  surface  of  the  perpendicular  portion  of  the  duodenum  by  a 
small  dilatation  which  is  common  to  it  and  to  the  ductus  communis 
choledochus,  and  passing  obliquely  between  the  mucous  and  muscu- 
lar coats  runs  from  right  to  left  through  the  middle  of  the  gland, 
lying  nearer  to  its  anterior  than  to  its  posterior  surface.  At  about 
the  commencement  of  the  apicial  third  of  its  course  it  divides  into 
two  parallel  terminal  branches.  It  gives  off  numerous  small 
branches,  which  are  distributed  through  the  lobules,  and  constitute 
with  the  latter  the  substances  of  the  gland.  The  duct  which  re- 
ceives the  secretion  from  the  lesser  pancreas  is  called  the  ductus 
pancreaticus  minor ;  it  opens  into  the  principal  duct  near  to  the  duo- 
denum, and  sometimes  passes  separately  into  that  intestine.  As  a 
variety,  two  pancreatic  ducts  are  occasionally  met  with. 

Vessels  and  Nerves. — The  arteries  of  the  pancreas  are  branches 
of  the  splenic,  hepatic,  and  superior  mesenteric  ;  the  veins  open  into 
the  splenic  vein ;  the  lymphatics  terminate  in  the  lumbar  glands. 
The  nerves  are  filaments  of  the  splenic  plexus. 

THE  SPLEEN. 

The  spleen  is  an  oblong  flattened  organ  of  a  dark  bluish-red  co- 
lour, situated  in  the  left  hypochondriac  region.  It  is  very  variable 
in  size  and  weight,  spongy  and  vascular  in  texture  and  exceedingly 
friable.  The  external  surface  is  convex,  the  internal  slightly  con- 
cave, indented  along  the  middle  fine,  and  pierced  by  several  large 
and  irregular  openings  for  the  entrance  and  exit  of  vessels ;  this  is 
the  hilus  llenis.  The  upper  extremity  is  somewhat  larger  than  the 
lower,  and  rounded ;  the  inferior  is  flattened ;  the  posterior  border 
is  obtuse ;  the  anterior  is  sharp  and  marked  by  several  notches. 
The  spleen  is  in  relation  by  its  external  or  convex  surface  with  the 
diaphragm,  which  separates  it  from  the  ninth,  tenth,  and  eleventh 
ribs ;  by  its  concave  surface  with  the  great  end  of  the  stomach,  the 
extremity  of  the  pancreas,  the  gastro-splenic  omentum  with  its  ves- 
sels, the  left  kidney  and  supra-renal  capsule,  and  with  the  left  crus 
of  the  diapliragm ;  by  its  upper  end  with  the  diaphragm,  and  some- 
times with  the  extremity  of  the  left  lobe  of  the  liver,  and  by  its  lower 
end  with  the  left  extremity  of  the  transverse  arch  of  the  colon.  It 
is  connected  to  the  stomach  by  the  gastro-splenic  omentum  and  by 


capsuLjE  renales.  525 

the  vessels  contained  in  that  duplicature.  A  second  spleen  (lien 
succenturiatus)  is  sometimes  found  appended  to  one  of  the  branches 
of  the  splenic  artery,  near  to  the  great  end  of  the  stomach  ;  when  it 
exists,  it  is  round  and  of  very  small  size,  rarely  larger  than  a  hazel- 
nut. I  have  seen  two  and  even  three  of  these  bodies.  The  spleen 
is  invested  by  the  peritoneum  and  by  a  tunica  propria  of  yellow 
elastic  tissue,  which  enables  it  to  yield  to  the  greater  or  less  disten- 
sion of  its  vessels.  The  elastic  tunic  forms  sheaths  for  the  vessels 
in  their  ramifications  through  the  organ,  and  from  these  sheaths 
small  fibrous  bands  are  given  off  in  all  directions,  which  become  at- 
tached to  the  internal  surface  of  the  elastic  tunic,  and  constitute  the 
cellular  framework  of  the  spleen.  The  substance  occupying  the 
interspaces  of  this  tissue  is  soft  and  granular,  and  of  a  bright  red 
colour ;  in  animals  it  is  interspersed  with  small,  white,  soft  corpus- 
cules. 

Vessels  and  Nerves. — The  Splenic  artery  is  of  a  very  large  size 
in  proportion  to  the  bulk  of  the  spleen ;  it  is  a  division  of  the  cceliac 
axis.  The  branches  which  enter  the  spleen  are  distributed  to  dis- 
tinct sections  of  the  organ,  and  anastomose  very  sparingly  with 
each  other.  The  veins  by  thin  numerous  dilatations  constitute  the 
principal  part  of  the  bulk  of  the  spleen ;  they  pour  their  blood  into 
the  splenic  vein,  which  is  one  of  the  two  great  formative  trunks  of 
the  portal  vein.  The  lymphatics  are  remarkable  for  their  number 
and  large  size,  they  terminate  in  the  lumbar  glands.  The  nerves 
are  the  splenic  plexus,  derived  from  the  solar  plexus. 

THE  SUPRA-RENAL  CAPSULES. 

The  supra-renal  capsules  are  two  small  yellowish  and  flattened 
bodies  surmounting  the  kidneys,  and  inclining  inwards  towards  the 
vertebral  column.  The  right  is  somewhat  three-cornered  in  shape, 
the  left  more  semilunar ;  they  are  connected  to  the  kidneys  by  the 
common  investing  cellular  tissue,  and  each  capsule  is  marked  upon 
its  anterior  surface  by  a  fissure  which  appears  to  divide  it  into  two 
lobes.  The  right  supra-renal  capsule  is  closely  adherent  to  the  pos- 
terior and  under  surface  of  the  liver,  and  the  left  lies  in  contact  with 
the  pancreas.  Both  capsules  rest  upon  the  crura  of  the  diaphragm 
on  a  level  with  the  tenth  dorsal  vertebra,  while  by  their  inner  border 
they  are  in  relation  with  the  great  splanchnic  nerve,  and  with  the 
semilunar  ganglion.  They  are  larger  in  the  foetus  than  in  the  adult, 
and  appear  to  perform  some  office  connected  wdth  embryonic  life. 
The  anatomy  of  these  organs  in  the  fa3tus  will  be  found  in  the  suc- 
ceeding chapter. 

In  structure  they  are  composed  of  two  substances,  cortical  and 
medullary.  The  cortical  substance  is  of  a  yellowish  colour,  and 
consists  of  straight  parallel  fibres  placed  perpendicularly  side  by 
side.  The  medullary  substance  is  generally  of  a  dark  brown  colour, 
double  the  quantity  of  the  yellow  substance,  soft  in  texture,  and 
contains  within  its  centre  the  trunk  of  a  large  vein — the  vena  supra- 


526  THE  KIDNEYS. 

renalis.  It  is  the  large  size  of  this  vein  that  gives  to  the  fresh  supra- 
renal capsule  the  appearance  of  a  central  cavity ;  the  dark-coloured 
pulpy  or  fluid  contents  of  the  capsule,  at  a  certain  period  after  death, 
are  produced  by  softening  of  the  medullary  substance.  Dr.  Nagel* 
has  shown,  by  his  injections  and  microscopic  examinations,  that  the 
appearance  of  straight  fibres  in  the  cortical  substance  is  caused  by 
the  direction  of  a  plexus  of  capillary  vessels.  Of  the  numerous 
minute  arteries,  supplying  the  supra-renal  capsule,  he  says,  the  greater 
number  enter  the  cortical  substance  at  every  point  of  its  surface, 
and,  after  proceeding  for  scarcely  half  a  line  in  its  substance,  divide 
into  a  plexus  of  straight  capillary  vessels.  Some  few  of  the  small 
arteries  pierce  the  cortical  layer  and  give  off  several  branches  in 
the  medullary  substance,  which  proceed  in  different  directions,  and 
re-enter  the  cortical  layer  to  divide  into  a  capillary  plexus  in  a 
similar  manner  with  the  preceding.  From  the  capillary  plexus, 
composing  the  cortical  layer,  the  blood  is  received  by  numerous 
small  veins  which  form  a  venous  plexus  in  the  medullary  substance, 
and  terminate  at  acute  angles  in  the  large  central  vein. 

Vessels  and  JVerves. — The  supra-renal  arteries  are  derived  from 
the  aorta,  from  the  renal,  and  from  the  phrenic  arteries ;  they  are 
remarkable  for  the  innumerable  minute  arteries  into  which  they 
divide  previously  to  entering  the  capsule.  The  supra-renal  vein 
collecting  the  blood  from  the  medullary  v^enous  plexus  and  receiving 
the  several  branches  which  pierce  the  cortical  layer,  opens  directly 
into  the  vena  cava  on  the  right  side,  and  into  the  renal  vein  on  the 
left. 

The  Lymphatics  are  large  and  very  numerous ;  they  terminate  in 
the  lumbar  glands.  The  nerves  are  derived  from  the  renal  and 
from  the  phrenic  plexus. 

THE  KIDNEYS. 

The  kidneys,  the  secreting  organs  of  the  urine,  are  situated  in  the 
lumbar  regions  behind  the  peritoneum,  and  on  each  side  of  the  ver- 
tebral column,  which  they  approach  by  their  upper  extremities. 
Each  kidney  is  between  four  and  five  inches  in  length,  about  two 
inches  and  a  half  in  breadth,  and  somewhat  more  than  one  inch  in 
thickness  ;  and  weighs  between  three  and  five  ounces.  The  kidneys 
are  usually  enclosed  in  a  quantity  of  fat,  they  rest  upon  the  dia- 
phragm, upon  the  anterior  lamella  of  the  transversalis  muscle,  M'hich 
separates  them  from  the  quadratus  lumborum,  and  upon  the  psoas 
magnus.  The  7v'ght  Iddneij  is  somewhat  lower  than  the  left,  from 
the  position  of  the  liver ;  it  is  in  relation  by  its  anterior  surface  with 
the  liver  and  descending  portion  of  the  duodenum,  which  rest  upon 
it,  and  is  covered  in  by  the  ascending  colon  and  by  its  flexure.  The 
left  kidney,  higher  than  the  right,  is  covered  in  front  by  the  great 
end  of  the  stomach,  by  the  spleen,  descending  colon  with  its  flexure, 

*  Mailer's  Archiv.  1836. 


STRUCTURE  OF  KIDNEYS. 


52T 


Fig.  156.* 


and  by  a  portion  of  the  small  intestines.  The  anterior  surface  of 
the  kidney  is  convex,  while  the  posterior  is  flat ;  the  superior  ex- 
tremity is  in  relation  with  the  supra-renal  capsule ;  the  convex 
border  is  turned  outwards  towards  the  parietes  of  the  abdomen; 
and  the  concave  border  looks  inwards  towards  the  vertebral  column, 
and  is  excavated  by  a  deep  fissure — the  hilus  renalis — in  which  are 
situated  the  vessels  and  nerves  and  pelvis  of  the  kidney ;  the  renal 
vein  being  the  most  anterior,  next  the  renal  artery,  and  lastly  the 
pelvis. 

The  kidney  is  dense  and  fragile  in  tex- 
ture, and  is  invested  by  a  proper  fibrous 
capsule,  which  is  easily  torn  from  its  sur- 
face. When  divided  by  a  longitudinal  in- 
cision carried  from  the  convex  to  the  con- 
cave border,  it  presents  in  its  interior  two 
structures,  an  external  or  vascular  (corti- 
cal), and  an  internal  or  tubular  (medullary) 
substance.  The  tubular  'portion  is  formed 
of  pale  reddish-coloured  conical  bodies  cor- 
responding by  their  bases  with  the  vascular 
structure,  and  by  their  apices  with  the  hilus 
of  the  organ ;  these  bodies  are  named  cones, 
and  are  from  eight  to  fifteen  in  number. 
The  vascular  'portion  is  composed  of  blood- 
vessels, and  of  the  plexiform  convolutions 
of  uriniferous  tubuli,  and  not  only  forms 
the  surface  of  the  kidney,  but  dips  between  the  cones  and  surrounds 
them  nearly  to  their  apices.  The  tubuli  uriniferi  communicate  fre- 
quently with  each  other  in  the  vascular  structure  of  the  kidney,  and 
terminate  in  anastomosing  loops  and  csecal  extremities.  They  are 
each  surrounded  by  a  fine  network  of  capillary  vessels.  When 
examined  with  a  lens  of  low  power,  a  muhitude  of  small  globular 
bodies,  glomeruli  (corpora  Malpighiana)  are  seen  to  be  interspersed 
through  the  vascular  structure  of  the  organ,  and  to  be  connected  to 
the  minute  twigs  of  the  arteries.  They  are  about  xroth  of  an  inch 
in  diameter,  are  composed  of  an  aggregated  plexus  of  capillary 
vessels,  and  enclose  a  small  central  cavity,  the  use  of  which  is  as 
yet  unknown. 

The  Cones  are  composed  of  minute  straight  tubuli  uriniferi  of 
about  the  diameter  of  a  fine  hair ;  they  divide  into  parallel  branches 
in  their  course,  and  commence  by  minute  openings  upon  the  apex 
or  papilla  of  each  cone.     The  papillte  are  invested  by  mucous  mem- 


*  A  section  of  the  kidney,  surmounted  by  the  supra-renal  capsule  ;  the  swellings 
upon  the  surface  mark  tlic  original  constitution  of  the  organ  by  distinct  lobes.  1.  The 
supra-renal  capsule.  2.  The  vascular  portion  of  the  kidney.  3,3,  Its  tubular  portion, 
consisting  of  cones.  4,  4.  Two  of  the  pnpillns  projecting  into  thin  corresponding 
calices.  5,  5,  5.  The  three  infundibuli ;  the  middle  5  is  situated  in  tlic  moutli  of  a 
caly-x.    6.  The  pelvis.    7.  The  ureter. 


528 


3IALE  PELVIS CONTEIVTS. 


brane,  which  is  continuous  with  the  hning  membrane  of  the  tubuh, 
and  forms  a  cup-hke  pouch,  the  cahjx,  around  each  papilla. 

■  The  cahces  communicate  with  a  common  cavity  of  larger  size, 
situated  at  each  extremity,  and  in  the  middle  of  the  organ  ;  and 
these  three  cavities — the  inf^indibula — constitute  by  their  union  the 
large  membranous  sac,  which  occupies  the  hilus  renalis,  the  ■pelvis 
of  the  kidney. 

The  kidney  in  the  embryo  and  fcetus  consists  of  lobules.  See  the 
anatomy  of  the  foetus  in  the  succeeding  chapter. 

The  Ureter  (o6^ov,  urine,  t%siv,  to  keep),  the  excretory  duct  of  the 
kidney,  is  a  membranous  tube  of  about  the  diameter  of  a  goose-quill, 
and  nearly  eighteen  inches  in  length ;  it  is  continuous  superiorly 
with  the  pelvis  of  the  kidney,  and  is  constricted  inferiorly,  where  it 
lies  in  an  oblique  direction  between  the  muscalar  and  mucous  coats 

Fig.  157.* 


*  A  side  view  of  the  viscera  of  the  male  pelvis  in  situ.  The  riafht  side  of  the  pelvis 
has  been  removed  by  a  vertical  section  made  througli  the  os  pubis  near  to  the  sym- 
physis;  and  another  through  the  middle  of  the  sacrum.  1.  The  divided  surface  of  tlie 
OS  pubis.  2.  The  divided  surface  of  the  sacrum.  3.  The  body  of  the  bladder.  A.  Its 
fundus;  from  tlie  apex  is  seen  passing  upwards  the  urachus.  5.  Tlic  base  of  the  blad- 
der. 6.  The  ureter.  7.  Tlie  neck  of  the  bladder.  8,  8.  The  pelvic  fascia ;  the  fibres 
immediately  above  7  are  given  off  from  the  pelvic  fascia  and  represent  the  anterior 
ligaments  of  the  bladder.  9.  The  prostate  gland.  10.  ''I'he  membranous  portion  of  tlio 
urethra,  between  tlie  two  layers  of  the  deep  perineal  fascia.  II.  Tlie  deep  perineal 
fascia  formed  of  two  layers.  12.  One  of  Cowper's  glands  between  the  two  layers  of 
deep  perineal  fascia,  and  bcneatli  the  membranous  ])ortion  of  tlie  urethra.  13.  Tiic 
bulb  of  the  corpus  sponjriosum.  14.  The  body  of  the  corpus  spongiosum.  1.5.  The 
right  erus  penis.  16.  I'he  upper  part  of  tlie  first  portion  of  tlio  rectum.  17.  The  recto- 
vesical fold  of  peritoneum.  18.  The  second  portion  of  llio  rectum.  19.  The  riglit 
vesicula  scminalis.  20.  The  vas  deferens.  21.  The  rectum  covered  with  tlie  descend- 
ing layer  of  the  pelvic  fascia,  just  as  it  is  making  its  bend  backwards  to  constitute  the 
third  portion.  22.  A  part  of  the  levator  ani  muscle  investing  the  lower  part  of  the  rec- 
tum. 23.  The  external  sphincter  ani.  24.  The  interval  between  the  deep  and  super- 
ficial perineal  fuscia;  they  arc  seen  to  be  continuous  beneath  the  figure. 


THE  PELVIS  AND  BLADDER.  529 

of  the  base  of  the  bladder,  and  opens  upon  its  mucous  surface. 
Lying  along  the  posterior  wall  of  the  abdomen,  it  is  situated  behind 
the  peritoneum  and  is  crossed  by  the  spermatic  vessels ;  in  its  course 
downwards  it  rests  upon  the  anterior  surface  of  the  psoas,  and 
crosses  the  common  iliac  artery  and  vein,  and  then  the  external 
iliac  vessels.  Within  the  pelvis  it  crosses  the  umbilical  artery  and 
the  vas  deferens  in  the  male,  and  the  upper  part  of  the  vagina  in  the 
female.     There  are  sometimes  two  ureters  to  one  kidney. 

The  ureter,  the  pelvis,  the  infundibula,  and  the  calices  are  com- 
posed of  two  coats,  an  external  or  fibrous  coat,  the  tunica  propria; 
and  an  internal  mucous  coat  which  is  continuous  with  the  mucous 
membrane  of  the  bladder  inferiorly,  and  with  the  lining  of  the  tubuli 
uriniferi  above. 

Vessels  and  JVerves. — The  renal  artery  is  derived  from  the  aorta ; 
it  divides  into  several  large  branches  before  entering  the  hilus. 
There  are  frequently  two  renal  arteries  and  sometimes  three. 

The  Veins  terminate  in  the  vena  cava  by  a  single  large  trunk  on 
each  side  ;  the  left  renal  vein  receiving  the  left  spermatic  vein.  In- 
jections thrown  into  the  renal  artery  and  returning  by  the  vein, 
generally  make  their  way  into  those  vessels  by  rupture ;  and  when 
the  injection  returns  by  the  tubuli  uriniferi,  it  always  occurs  from 
the  bursting  of  the  capillary  vessels  of  the  ducts  into  their  cavities. 
The  lymphatic  vessels  terminate  in  the  lumbar  glands. 

The  JVej^ves  are  derived  from  the  renal  plexus,  which  is  formed 
partly  by  the  solar  plexus,  and  partly  by  the  lesser  splanchnic  nerve. 
The  renal  plexus  gives  branches  to  the  spermatic  plexus,  and 
branches  which  accompany  the  ureters  :  hence  the  morbid  sympa- 
thies which  exist  between  the  kidney,  the  ureter,  and  the  testicle ; 
and  by  the  communications  with  the  solar  plexus,  with  the  stomach 
and  diaphragm,  and  indeed  with  the  whole  system. 

THE  PELVIS. 

The  cavity  of  the  pelvis  is  that  portion  of  the  great  abdominal 
cavity  which  is  included  within  the  bones  of  the  pelvis,  below  the 
level  of  the  linea-ilio-pectinea  and  the  promontory  of  the  sacrum. 
It  is  bounded  by  the  cavity  of  the  abdomen  above,  and  by  the  peri- 
neum below ;  its  internal  parietes  are  formed  in  front,  below,  and  at 
the  sides,  by  the  peritoneum,  pelvic  fascia,  levatores  ani  muscles, 
obturator  fascias  and  muscles ;  and  behind,  by  the  sacrum,  and 
sacral  plexus  of  nerves. 

The  Viscera  of  the  pelvis  in  the  male  are  the  urinary  bladder,  the 
prostate  gland,  vesiculas  seminales,  and  the  rectum. 

BLADDER. 

The  Bladder  is  an  oblong  membranous  viscus  of  an  ovoid  shape, 
situated  behind  the  os  pubis  and  in  front  of  the  rectum.  It  is  larger 
in  its  vertical  diameter  than  from  side  to  side ;  and  its  long  axis  is 

67 


530  LIGAMENTS  OP  THE  BLADDER. 

directed  from  above,  obliquely  downwards  and  backwards.  It  is 
divided  into  body,  fundus,  base,  and  neck.  The  hodij  comprehends 
the  middle  zone  of  the  organ  •  the  fundus,  its  upper  segment ;  the 
base,  the  lower  broad  extremity,  which  rests  upon  the  rectum ;  and 
the  neck  the  narrow  constricted  portion  which  is  applied  against  the 
prostate  gland. 

This  organ  is  retained  in  its  place  by  ligaments  which  are  divided 
into  true  and  false ;  the  true  ligaments  are  seven  in  number,  two 
anterior,  two  lateral,  two  umbiUcal,  and  the  urachus ;  the  false  liga- 
ments are  folds  of  the  peritoneum,  and  are  four  in  number,  tw"o  an- 
terior and  two  posterior. 

The  Anterior  ligaments  are  formed  by  the  pelvic  fascia,  which 
passes  from  the  inner  surface  of  the  os  pubis,  on  each  side  of  the 
symphysis,  to  the  front  of  the  bladder. 

The  Lateral  ligaments  are  formed  by  the  reflection  of  the  pelvic 
fascia  from  the  levatores  ani  muscles,  upon  the  sides  of  the  base  of 
the  bladder. 

The  Umbilical  ligaments  are  the  fibrous  cords  which  result  from 
the  obliteration  of  the  umbilical  arteries  of  the  foetus  ;  they  pass  for- 
wards on  each  side  of  the  fundus  of  the  bladder,  and  ascend  beneath 
the  peritoneum  to  the  umbilicus. 

The  Urachus  is  a  small  fibrous  cord  formed  by  the  obliteration  of 
a  tubular  canal  existing  in  the  embryo ;  it  is  attached  to  the  apex  of 
the  bladder,  and  thence  ascends  to  the  umbilicus. 

The  False  ligaments  are  folds  of  peritoneum,  the  two  lateral  cor- 
respond with  the  passage  of  the  vasa  deferentia,  from  the  sides  of 
the  bladder  to  the  internal  abdominal  rings,  and  the  two  posterior 
with  the  course  of  the  umbilical  arteries,  to  the  fundus  of  the  organ. 

The  bladder  is  composed  of  three  coats,  an  external  or  serous 
coat,  a  muscular  and  a  mucous  coat.  The  serous  coat  is  partial, 
and  derived  from  the  peritoneum,  which  invests  the  posterior  sur- 
face and  sides  of  the  bladder,  from  about  opposite  the  point  of  termi- 
nation of  the  two  ureters  to  its  summit,  whence  it  is  guided  to  the 
anterior  wall  of  the  abdomen  by  the  umbilical  ligaments  and  urachus. 
The  muscular  coat  consists  of  two  layers,  an  external  layer  com- 
posed of  longitudinal  fibres,  the  detrusor  urinse ;  and  an  internal 
layer  of  oblique  and  transverse  fibres  irregularly  distributed.  The 
anterior  longitudinal  fibres  commence  by  four  branches  (the  tendons 
of  the  bladder,  or  of  the  detrusor  urinaj),  two  superior  from  the  os 
pubis,  and  two  inferior  from  the  ramus  of  the  ischium  on  each  side, 
and  spread  out  as  they  ascend  upon  the  anterior  surface  of  the  blad- 
der to  its  fundus ;  they  then  converge  upon  the  posteiior  surface  of 
the  organ,  and  descend  to  its  neck  where  they  arc  inserted  into  the 
isthmus  of  the  prostate  gland,  and  into  a  ring  of  elastic  tissue,  which 
surrounds  the  commencement  of  the  prostatic  portion  of  the  urethra. 
Some  of  the  anterior  fibres  are  also  attached  to  this  ring.  The 
lateral  fibres  commence  at  the  prostate  gland  and  the  elastic  ring  of 
the  urethra  on  one  side,  and  spread  out  as  they  ascend  upon  tlic 
side  of  the  bladder  to  descend  upon  the  opposite  side,  and  l)e  in- 
serted into  the  prostate  and  opposite  segment  of  the  same  ring.  Two 


BLADDER. 


531 


bands  of  oblique  fibres  are  described  by  Sir  Charles  Bell,  as  origi- 
ginating  at  the  terminations  of  the  ureters,  and  converging  to  the 
neck  of  the  bladder;  the  existence  of  these  muscles  is  not  well  es- 
tablished. 

It  has  been  well  shown  by  Mr.  Guthrie,*  that  there  are  no  fibres 
at  the  neck  of  the  bladder  capable  of  forming  a  sphincter  vesicas. 
The  fibres  corresponding  with  the  trigonum  vesicas  are  transverse. 

Sir  Astley  Cooper  has  demonstrated  around  the  neck  of  the  bladder 
within  the  prostate  gland,  a  ring  of  elastic  tissue,  which  has  for  its 
object  the  mechanical  closure  of  the  urethra  against  the  involuntary 
passage  of  the  urine.  It  is  into  this  elastic  ring  that  the  longitudinal 
fibres  of  the  detrusor  urinas  are  inserted,  so  that  this  muscle  taking 
a  fixed  point  at  the  os  pubis  will  not  only  compress  the  bladder,  and 
thereby  tend  to  force  its  contents  along  the  urethra ;  but  will  at  the 
same  time,  by  means  of  its  attachment  to  this  ring  dilate  the  en- 
trance of  the  urethra,  and  afford  a  free  egress  to  the  contents  of  the 
bladder.f 

*  "On  the  Anatomy  and  Diseases  of  the  Neck  of  the  Bladder  and  of  the  Urethra." 
t  In  Horner's  Special  Anatomy,  vol.  ii.  p.  82,  we  find  a  different  account  of  the 
sphincter  apparatus  at  the  neck  of  the  bladder,  which  I  subjoin  because  I  have  found 
it  correct  in  every  case  wliich  I  have  examined.  On  one  point  I  beg  leave  to  differ 
from  Prof.  Horner's  description,  viz. :  in  place  of  considering'  the  transverse  band  con- 
necting the  two  lobes  of  the  prostate,  and  the  triangular  lamina  underlying  the  vesical 
triangle  as  muscular,  I  believe  them  to  belong  to  the  proper  elastic  tissue  such  as  forms 
the  ligamentum  nuchas  in  the  mammiferaj  and  the  middle  coat  of  the  arterial  system. 
I  annex  a  cat  to  the  description  of  Horner,  taken  by  his  permission  from  a  drawing 
by  Peale. — G. 


Fig.  158.t 


"  The  internal  orifice  of  the  neck  of 
the  bladder  resembles  strongly  that  of  a 
Florence  flask,  modified,  however,  by 
the  projection  of  the  uvula  vesicte,  which 
makes  it  somewhat  crescentic  below. 
The  neck  of  the  bladder  penetrates  the 
prostate  gland,  but,  at  its  commence- 
ment, is  surrounded  by  loose  cellular 
tissue  containing  a  very  large  and  abun- 
dant plexus  of  veins.  The  internal  layer 
of  muscular  fibres  is  here  transverse ; 
and  they  cross  and  intermix  with  each 
other  in  different  directions,  forming  a 
close  compact  tissue,  which  has  the 
effect  of  a  particular  apparatus  for  re- 
taining the  urine,  and  is  called  muscu- 
lus  sphincter  vesicce  urinariae.  Gene- 
rally, anatomists  have  not  considered 
this  structure  as  distinct  from  the  mus- 
cular coat  at  large  ;  but  Sir  Charles  Bell, 
now  a  professor  in  the  University  of 
Edinburgh,  whose  reputation  as  an  ana. 
tomist  is  well  established,  gives  the  fol- 
lowing account  of  it : — 

"  '  Begin  the  dissection  by  taking  off 
the  inner  membrane  of  the  bladder  from 
around  the  orifice  of  the  urethra.  A  set 
of  fibres  will  be  discovered,  on  the  lower 

t  Represents  the  neck  of  the  bladder  with  the  sphincter  apparatus  as  described  by 
Horner.  1,  1.  Orifice  of  the  neck  of  the  bladder.  2,  2,  2,  2.  Orifices  of  the  ureters. 
3,  3.  Tiie  triangular  tissue,  supposed  to  be  muscular  under  the  mucous  membrane  of 
the  vesical  triangle.  4,  4.  Part  of  the  detrusor  urina  muscle.  5.  The  elastic  band 
which  acts  as  a  constant  sphincter  to  the  neck  of  the  bladder. — G. 


532  PROSTATE  GLAND. 

The  Mucous  coat  is  thin  and  smooth  and  exactly  moulded  upon 
the  muscular  coat,  to  wliich  it  is  connected  by  a  somewhat  thick 
layer  of  submucous  tissue,  called  by  some  anatomists,  the  nervous 
coat ;  its  papillce  are  very  minute,  and  there  is  scarcely  a  trace  of 
mucous"  follicles.  This  mucous  membrane  is  continuous  through 
the  ureters  with  the  lining  membrane  of  the  uriniferous  ducts  and 
through  the  urethra,  with  that  of  the  prostatic  ducts,  tubuli  semi- 
niferi,  and  Cowper's  glands. 

Upon  the  internal  surface  of  the  base  of  the  bladder  is  a  triangu- 
lar smooth  plane  of  a  paler  colour  than  the  rest  of  the  mucous  mem- 
brane ;  the  trigonum  vesicae,  or  trigone  vesicale.  This  is  the  most 
sensitive  part  of  the  bladder,  and  the  pressure  of  calculi  upon  it  gives 
rise  to  great  saflering.  It  is  bounded  on  each  side  by  the  raised 
ridge,  corresponding  with  the  muscles  of  the  ureters,  at  each  pos- 
terior angle  by  the  openings  of  the  ureters,  and  in  front  by  a  slight 
elevation  of  the  mucous  membrane  at  the  entrance  of  the  urethra, 
called  the  uvula  vesicce. 

The  external  surface  of  the  base  of  the  bladder  corresponding 
with  the  trigonum,  is  also  triangular,  and  is  separated  from  the 
rectum  merely  by  a  thin  layer  of  fibrous  membrane,  the  recto-vesical 
fascia.  It  is  bounded  behind  by  the  recto-vesical  fold  of  peritoneum ; 
and  on  each  side  by  the  vas  deferens,  and  vesicula  seminalis,  which 
converge  almost  to  a  point  at  the  base  of  the  prostate  gland.  It  is 
through  this  space  that  the  opening  is  made  in  the  recto-vesical 
operation  for  puncture  of  the  bladder. 

PROSTATE  GLAND. 

The  prostate  gland  {•n'^oldrfiit.i  proeponere)  is  situated  in  front  of  the 
neck  of  the  bladder  behind  the  deep  perineal  fascia  and  upon  the 

half  of  the  orifice,  which,  being  carefully  dissected,  will  be  found  to  run  in  a  semi- 
circular form  round  llie  urethra.  These  fibres  make  a  band  of  about  half  an  inch  in 
breadth,  particularly  strong  on  the  lower  part  of  the  opening,  and,  having  mounted  a 
little  above  the  orifice,  on  each  side,  they  dispose  of  a  portion  of  their  fibres  in  the 
substance  of  the  bladder.  A  smaller  and  somewhat  weaker  set  of  fibres  will  be  seen 
to  complete  their  course,  surrounding  the  orifice  on  the  upper  part ;  to  these  sphincter 
fibres  a  bridle  is  joined,  which  comes  from  the  union  of  the  muscles  of  the  ureters.' 

"  After  repeated  observations  on  this  point,  I  have  come  to  the  conclusion  that  Mr. 
Bell  has  indicated  a  real  structure  ;  but  my  own  dissections  have  resulted  as  follows  : 
The  inferior  semicircumferencc  of  the  neck  of  the  bladder  is  surrounded  by  a  thick 
fasciculus  of  muscular  fibre,  half  an  inch  wide,  running  in  a  transverse  direction,  and 
having  its  ends  attached  to  the  lateral  lobes  of  the  prostate  gland,  being  above  the  third 
lobe  of  the  latter.  This  fasciculus  is  perfectly  distinct  from  the  ordinary  muscular 
fibre  of  the  bladder,  and  resembles  in  its  texture  the  musculo-fibrous  coat  of  the  arte- 
ries. The  superior  semicircumferencc  is  also  surrounded  by  a  thin  layer  of  muscular 
fibres  of  an  ordinary  kind,  forming  a  broad,  thin  band  of  a  crcsccntic  shape,  the  lower 
ends  of  which  arc  insensibly  lost  in  the  adjacent  muscular  coat  of  the  bladder  by  being 
spread  out.  And,  lastly,  beneath  the  mucous  membrane  of  tlie  vesical  triangle  there 
is  a  triangular  muscle  of  the  same  size  as  the  vesical  triangle.  Having  elongated 
angles,  the  anterior  angle  may  be  traced  to  the  posterior  part  of  the  caput  gallinaginis, 
and  the  posterior  angles  to  the  orifices  of  the  ureters  and  the  adjacent  part  of  the 
l)laddcr.  The  texture  of  this  muscle-  is  also  like  that  of  tlie  musculo-fibrous  coat  of 
the  arteries.  When  a  bladder  is  recent,  this  detail  of  structure  is  made  out  with  diffi- 
culty :  it  recpiires  to  be  ])reviously  hnrdened  in  spirits  of  wine.  That  a  power  exists 
in  the  neck  of  the  bladder  of  retaining  completely  the  urine,  has  been  satisfactorily 
demonstrated  to  me  in  a  case  of  fistula  in  pcrinco,  which  was  presented  to  the  notice' 
of  the  late  Dr.  Fhyeick  and  myself,  a  few  years  ago." 


VESICUL^  SEMINALES.  533 

rectum,  through  which  it  may  be  distinctly  felt.  It  surrounds  the 
commencement  of  the  urethra  for  a  little  more  than  an  inch  of  its 
extent,  and  resembles  a  Spanish  chestnut  both  in  size  and  form ;  the 
base  being  directed  backwards  towards  the  neck  of  the  bladder,  the 
apex  forwards,  and  the  convex  side  towards  the  rectum.  It  is  re- 
tained firmly  in  its  position  by  the  two  superior,  and  the  two  inferior 
tendons  of  the  bladder,  by  the  attachments  of  the  pelvic  fascia,  and 
by  a  process  of  the  internal  layer  of  the  deep  perineal  fascia,  which 
forms  a  sheath  around  the  membranous  urethra,  and  is  inserted  into 
the  apex  of  the  gland.  It  consists  of  three  lobes,  two  lateral  and  a 
middle  lobe  or  isthmus ;  the  lateral  lobes  are  distinguished  by  an  in- 
dentation upon  the  base  of  the  gland,  and  by  a  slight  furrow  upon 
its  upper  and  lower  surface.  The  third  lobe  or  isthmus  is  a  small 
transverse  band  which  passes  between  the  two  lateral  lobes  at  the 
base  of  the  organ.  In  structure  the  prostate  gland  is  composed  of 
ramified  ducts,  terminating  in  lobules  of  follicular  pouches  which 
are  so  closely  compressed  as  to  give  to  a  thin  section  of  the  gland  a 
cellular  appearance  beneath  the  microscope.  It  is  pale  in  colour 
and  hard  in  texture,  splits  easily  in  the  course  of  its  ducts,  and  is 
surrounded  by  a  plexus  of  veins  which  are'  enclosed  by  the  strong 
fibrous  membrane  with  which  it  is  invested.  Its  secretion  is  poured 
into  the  prostatic  portion  of  the  urethra  by  fifteen  or  twenty  excre- 
tory ducts.  The  urethra  in  passing  through  the  prostate  lies  one 
third  nearer  to  its  upper  than  to  its  lower  surface. 

VESICULiE  SEMINALES. 

Upon  the  under  surface  of  the  base  of  the  bladder,  and  converging 
towards   the  base  of  the  prostate   gland, 
are  two  lobulated  and  somewhat  pyriform  Fig.  159* 

bodies,  about  two  inches  in  length,  the  vesi- 
cuIjb  seminales.  Their  upper  surface  is  in 
contact  with  the  base  of  the  bladder;  the 
under  side  rests  upon  the  rectum,  separated 
only  by  the  recto-vesical  fascia ;  the  larger 
extremities  are  directed  backwards  and 
outwards,  and  the  smaller  ends  almost  meet 
at  the  base  of  the  prostate.  They  enclose 
between  them  a  triangular  space,  which  is 
bounded  posteriorly  by  the  recto-vesical  fold 
of  peritoneum,  and  which  corresponds  with 
the  trigonum  vesicas  on  the  interior  of  the 
bladder.  Each  vesicula  is  formed  by  the 
convolutions  of  a  single  tube,  which  gives 
off  several  irregular  cajcal  branches.     It  is 

*  The  posterior  aspect  of  the  male  bladder ;  the  serous  covering  is  removed  in  order 
to  show  the  muscular  coat.  1.  The  body  of  the  bladder.  2.  Its  fundus.  3.  Its  inferior 
fundus  or  base.  4.  The  urachus.  5,  5,  The  ureters.  6,  6.  The  vasa  defcrcntia.  7, 
7.  The  vcsiculce  seminales.  The  triangular  area,  corresponding  with  tJie  trigonum 
vesicfB  tlu-ough  which  tlic  bladder  would" be  pierced,  in  puncttiring  the  bladder  tln-ough 
the  rectum.  The  dotted  line  forming  the  base  of  this  triangular  area,  marks  the  ex- 
tent of  the  recto-vesical  fold  of  the  peritoneum. 


534  MALE  ORGANS  OF  GENERATION. 

enclosed  in  a  dense  fibrous  membrane,  derived  from  the  pelvic  fascia, 
and  is  constricted  beneatli  the  isthmus  of  the  prostate  gland  into  a 
small  excretory  duct.  The  vas  deferens,  somewhat  enlarged  and 
convoluted,  lies  along  the  inner  border  of  each  vesicula,  and  is  in- 
cluded in  its  fibrous  investment.  It  communicates  with  the  duct  of 
the  vesicula,  beneath  the  isthmus  of  the  prostate,  and  forms*  the 
ejaculatory  duct.  The  ejaculatory  duct  is  about  three  quarters  of 
an  inch  in  length,  and  running  forwards,  first  between  the  base  of 
the  prostate  and  the  isthmus  and  then  through  the  elastic  tissue  of 
the  veru  montanum,  opens  upon  the  mucous  membrane  of  the 
urethra,  near  to  its  fellow  of  the  opposite  side,  at  the  anterior  ex- 
tremity of  that  process. 

MALE  ORGANS  OF  GENERATION. 

The  organs  of  generation  in  the  male  are,  the  penis  and  the  testes, 
with  their  appendages. 

The  Penis  is  divided  into  a  body,  root,  and  extremity.  The  body 
is  surrounded  by  a  thin  integument,  which  is  remarkable  for  the 
looseness  of  its  cellular  connexion  with  the  deeper  parts  of  the 
organ,  and  for  containing  no  adipose  tissue.  The  root  is  broad,  and 
firmly  adherent  to  the  rami  of  the  os  pubis  and  ischium  by  means 
of  two  strong  processes,  the  crura,  and  is  connected  to  the  sym- 
physis pubis  by  a  fibrous  membrane,  the  ligamentum  suspensorium. 
The  extremity,  or  glans  penis  resembles  an  obtuse  cone,  somewhat 
compressed  from  above  downwards,  and  of  a  deeper  red  colour 
than  the  surrounding  skin.  At  its  apex  is  a  small  vertical  slit,  the 
meatus  urinarius,  which  is  bounded  by  two  more  or  less  protuberant 
labia :  and,  extending  backwards  from  the  meatus,  is  a  depressed 
raphe,  to  which  is  attached  a  loose  fold  of  mucous  membrane,  the 
fraenum  prceputii.  The  base  of  the  glans  is  marked  by  a  projecting 
collar,  the  corona  glandis,  upon  which  are  seen  a  number  of  small 
papillary  elevations,  formed  by  the  aggregation  of  minute  sebaceous 
glands,  the  glandulas  Tysoni  (odorifera?).  Behind  the  corona  is  a 
deep  fossa,  bounded  by  a  circular  fold  of  integument,  the  prcBpuVntm, 
which,  in  the  quiescent  state  of  the  organ,  may  be  drawn  over  the 
glans,  but,  in  its  distended  state,  is  obliterated,  and  serves  to  facili- 
tate its  enlargement.  The  internal  surface  of  the  prepuce  is  lined 
by  mucous  membrane,  covered  by  a  thin  cuticle ;  this  membrane, 
upon  reaching  the  base  of  the  glans,  is  reflected  over  the  glans  penis, 
and,  at  the  meatus  urinarius,  becomes  continuous  with  the  mucous 
lining  of  the  urethra. 

*  It  has  bocn  customary  hitherto,  in  works  on  anatomy,  to  describe  the  course  of 
excretory  ducts  as  proceeding  from  the  jrland,  and  passing-  tlicncc  to  tlic  point  at  wiiich 
tlie  secretion  is  jiourcd  out.  In  the  description  of  tiie  vas  deferens,  with  its  connexion 
with  tiie  duct  of  the  vesicula  seminalis,  I  liavc  adopted  this  plan,  that  I  might  not  too 
far  depart  from  cstaljlislied  habit.  But  as  it  is  more  correct  and  consistent  with  tlie 
present  state  of  science  to  consider  the  gland  as  a  dev(;lopement  of  tlie  duet,  I  have 
pursued  the  latter  principle  in  the  description  of  most  of  the  other  glandular  organs  of 
the  body. 


CORPUS  SPONGIOSUM ERECTILE  TISSUE.  535 

The  penis  is  composed  of  the  corpus  cavernosum  and  corpus 
spongiosum,  and  contains  in  its  interior  the  longest  portion  of  the 
urethra. 

The  Corpus  cavernosum  is  distinguished  into  two  lateral  portions 
(corpora  cavernosa),  by  an  imperfect  septum  and  by  a  superior  and 
inferior  groove,  and  is  divided  posteriorly  into  iwvo  crura.  It  is 
firmly  adherent,  by  means  of  its  crura,  with  the  ramus  of  the  os 
pubis  and  ischium.  It  forms,  anteriorly,  a  single  rounded  extremity, 
which  is  received  into  a  fossa  in  the  base  of  the  glans  penis ;  the 
superior  groove  lodges  the  dorsal  vessels  of  the  organ,  and  the  infe- 
rior receives  the  corpus  spongiosum.  Its  fibrous  tunic  is  thick, 
elastic,  and  extremely  firm,  and  sends  a  number  of  fibrous  bands 
and  cords  (trabeculse)  inwards  from  its  inferior  groove,  which  cross 
its  interior  in  a  radiating  direction,  and  are  inserted  into  the  inner 
walls  of  the  tunic.  These  trabeculse  are  most  abundant  on  the 
middle  line,  where  they  are  ranged  vertically,  side  by  side,  some- 
what like  the  teeth  of  a  comb,  and  constitute  the  imperfect  partition 
of  the  corpus  cavernosum,  called  the  septum  pectiniforme.  This 
septum  is  more  complete  at  its  posterior  than  towards  its  anterior 
part. 

The  tunic  of  the  corpus  cavernosum  consists  of  strong  longitu- 
dinal fibrous  fasciculi,  closely  interwoven  with  each  other.  Its 
internal  structure  is  com^posed  of  erectile  tissue. 

The  Corpus  spongiosum  is  situated  along  the  under  surface  of  the 
corpus  cavernosum,  in  its  inferior  groove.  It  commences  by  its 
posterior  extremity  between  and  beneath  the  crura  penis,  where 
it  forms  a  considerable  enlargement,  the  bulb,  and  terminates  an- 
teriorly by  another  expansion,  the  glans  penis.  Its  middle  portion, 
or  body,  is  nearly  cylindrical,  and  tapers  gradually  from  its  pos- 
terior towards  its  anterior  extremity.  The  bulb  is  adherent  to  the 
deep  perineal  fascia  by  means  of  the  tubular  prolongation  of  the  an- 
terior layer,  which  surrounds  the  membranous  portion  of  the  urethra; 
in  the  rest  of  its  extent  the  corpus  spongiosum  is  attached  to  the 
corpus  cavernosum  by  cellular  tissue,  and  by  veins  which  wind 
around  that  body  to  reach  the  dorsal  vein.  It  is  composed  of  erec- 
tile tissue,  enclosed  by  a  dense  fibrous  tissue,  much  thinner  than  that 
of  the  corpus  cavernosum,  and  contains  in  its  interior  the  spongy 
portion  of  the  urethra,  which  lies  nearer  to  its  upper  than  to  its  lower 
wall. 

Erectile  tissue  is  a  peculiar  cellulo-vascular  structure,  entering  in 
considerable  proportion  into  the  composition  of  the  organs  of  gene- 
ration. It  consists  essentially  of  a  plexus  of  veins  so  closely  con- 
voluted and  interwoven  with  each  other,  as  to  give  rise  to  a  cellular 
appearance  when  examined  upon  the  surface  of  a  section.  The 
veins  forming  this  plexus  are  smaller  in  the  glans  penis,  coquis  spon- 
giosum, and  circumference  of  the  corpus  cavernosum,  than  in  the 
central  part  of  the  latter,  where  they  are  large  and  dilated.  They 
have  no  other  coat  than  the  internal  lining  prolonged  from  the 
neighbouring  veins  ;  and  the  interstices  of  the  plexus  are  occupied 


536  URETHRA. 

by  a  peculiar  reddish  fibrous  substance.  They  receive  their  blood 
from  the  capillaries  of  the  arteries  in  the  same  manner  with  veins 
generally,  and  not  by  means  of  vessels  having  a  peculiar  form  and 
distribution,  as  described  by  Miiller.  The  helicine  arteries  of  that 
physiologist  have  no  existence.* 

Vessels  and  Nerves. — The  arteries  of  the  penis  are  derived  from 
the  internal  pudic  ;  they  are,  the  arteries  of  the  bulb,  arteries  of  the 
corpus  cavernosum,  and  dorsalis  penis.  Its  veins  are  superficial  and 
deep.  The  deep  veins  run  by  the  side  of  the  deep  arteries,  and  ter- 
minate in  the  internal  pudic  veins.  The  superficial  veins  emerge  in 
considerable  number  from  the  base  of  the  glans,  and  converge  on 
the  dorsum  penis,  to  form  a  large  dorsal  vein,  which  receives  othei: 
veins  from  the  corpus  cavernosum  and  spongiosum  in  its  course,  and 
passes  backwards  between  two  layers  of  the  ligamentum  suspen- 
sorium,  and  through  the  deep  fascia  beneath  the  arch  of  the  os  pubis, 
to  terminate  in  the  prostatic  and  vesical  plexuses. 

The  Lymphatics  terminate  in  the  inguinal  glands.  The  nerves  are 
derived  from  the  internal  pudic  nerve,  from  the  sacral  plexus,  and, 
as  shown  by  Professor  Miiller  in  his  beautiful  monograph,  from  the 
hypogastric  plexus. 

URETHRA. 

The  urethra  is  the  membranous  canal  extending  from  the  neck 
of  the  bladder  to  the  meatus  urinarius.  It  is  sigmoid  in  its  course, 
and  is  composed  of  two  layers,  a  mucous  coat  and  an  elastic  fibrous 
coat.  The  mucous  coat  is  thin  and  smooth ;  it  is  continuous,  inter- 
nally, with  the  mucous  membrane  of  the  bladder  ;  externally,  with 
the  investing  membrane  of  the  glans ;  and,  in  certain  points  of  its 
extent,  with  the  lining  membrane  of  the  numerous  ducts  of  mucous 
glands, — of  those  of  Cowper's  glands,  the  prostate  gland,  vasa 
deferentia,  and  vesicula;  seminales.  The  elastic  fibrous  coat  varies 
in  thickness  in  the  different  parts  of  the  course  of  the  urethra :  it  is 
thick  in  the  prostate  gland,  forms  a  firm  investment  for  the  mem- 
branous portion  of  the  canal,  and  is  thin  in  the  spongy  portion, 
where  it  serves  as  a  bond  of  connexion  between  the  mucous  mem- 
brane and  the  corpus  spongiosum.  The  urethra  is  about  nine  inches 
in  length,  and  is  divided  into  a  prostatic,  membranous,  and  spongy 
portion. 

The  Prostatic  portion,  a  little  more  than  an  inch  in  length,  is 
situated  in  the  prostate  gland,  about  one-third  nearer  to  its  upper 
than  to  its  lower  surface,  and  extending  from  its  base  to  its  apex. 
Upon  its  lower  circumference  or  floor  is  a  longitudinal  fold  of  mucous 
membrane — the  verumontanum,  or  caput  gallinaginis, — and  on  each 
side  of  the  veru,  a  depressed  fossa — the  prostatic  sinus — in  which 
are  seen  the  numerous  openings  of  the  prostatic  ducts.  At  the  an- 
terior extremity  of  the  verumontanum  are  the  openings  of  the  two 

*  Soc  my  investigation  upon  this  structure  in  the  "  Cyclopaedia  of  Anatomy  and 
Pliysiology."     Article,  "  Penis." 


URETHRA  AND  BLADDER. 


537 


ejaculatory  ducts,  and  between  them  a  third  opening,  which  leads 
backwards  into  a  small  dilated  sac — the  sinus  pocularis.  The  pro- 
static portion  of  the  urethra,  when  distended,  is  the  most  dilated  part 
of  the  canal ;  but,  excepting  during  the  passage  of  urine,  is  com- 
pletely closed  by  means  of  a  ring  of  elastic  tissue  which  encircles 
the  urethra  as  far  as  the  anterior  extremity  of  the  verumontanum. 
In  the  contracted  state  of  the  urethra,  the  verumontanum  acts  as 
a  valve,  being  pressed  upwards  against  the  upper  wall  of  the  canal; 
but,  during  the  action  of  the  detrusor  muscle  of  the  bladder,  the 
whole  elastic  ring  is  expanded  by  the  muscular  fibres  which  are 
inserted  into  it ;  and  the  veru  is  especially  drawn  downwards  by 
two  delicate  tendons,  which  have  been  traced  by  Mr.  Tyrrell, 
from  the  posterior  fibres  of  the  detrusor  into  the  tissue  of  this 
process. 

Fiff.  160* 


*  A  longitudinal  section  of  the  bladder,  prostate  gland,  and  penis,  showin'r  the 
urethra.  1.  The  urachiis  attached  to  the  upper  part  of  the  fundus  of  tlie  bladder.  2. 
The  recto-vesical  fold  of  peritoneum,  at  its  point  of  reflection  from  the  base  of  the 
bladder,  upon  the  anterior  surface  of  the  rectum.  3.  The  opening  of  the  right  ureter. 
4.  A  slight  ridge,  formed  by  the  muscle  of  the  ureter,  and  extending  from  the  termi- 
nation of  the  ureter  to  tlie  commencement  of  the  urethra.  This  ridge  forms  the  lateral 
boundary  of  the  trigonum  vesicEE.  5.  The  commencement  of  tlie  urethra ;  the  eleva- 
tion of  mucous  membrane  immediately  behind  the  figure  is  the  uvula  vesica.  The 
constriction  of  the  bladder  at  this  point  is  the  necli  of  the  bladder.  6.  The  prostatic 
portion  of  the  uretlira.  7.  The  prostate  gland ;  the  diiference  of  tliickness  of  the 
gland,  above  and  below  the  urethra,  is  shown.  8.  The  isthmus,  or  third  lobe  of  the 
prostate ;  immediately  beneath  which  the  ejaculatory  duct  is  seen  passing.  9.  The 
right  vesicula  seminalis  ;  the  vas  deferens  is  seen  to  be  cut  short  off,  close  to  its  junc- 
tion with  the  ejaculatory  duct.  10.  The  membranous  portion  of  the  urethra.  11. 
Cowper's  gland  of  the  right  side,  with  its  duct.  12.  The  bulbous  portion  of  the 
urethra ;  throughout  the  whole  length  of  the  urethra  of  the  corpus  spongiosum,  nu- 
merous lacunas  are  seen.  13.  The  fossa  navicularis.  14.  The  corpus  cavernosum,  cut 
somewhat  obliquely  to  the  right  side,  near  its  lower  part.  Tlie  character  of  the  venous- 
cellulnr  texture  is  well  shown.  15.  The  right  cms  penis.  16.  Near  the  upper  part  of 
the  corpus  cavernosum,  the  section  has  fallen  a  little  to  tlie  left  of  tiie  middle  line;  a 
portion  of  the  septum  pcctiniforme  is  consequently  seen.  Tliis  figure  also  indicates 
the  thickness  of  the  fibrous  investment  of  the  corpus  cavernosum,  and  its  abrupt  ter- 
mination at  the  base  of  (17)  the  glans  penis.  \b.  The  lower  segment  of  the  glans. 
19.  The  meatus  urinarius.  20.  The  corpus  spongiosum.  21.  The  bulb  of  the  corpus 
spongiosum. 

G8 


533  MEMBRANOUS  URETHRA. 

The  discovery  ojf  this  beautiful  structure  is  due  to  our  distin- 
guished countryman,  Sir  Astley  Cooper,  and  is  one  other  instance 
of  the  marvellous  indications  of  design  evinced  in  the  structure  of 
the  animal  frame.  Instead  of  a  muscular  apparatus,  liable  to  fatigue, 
Nature  has  employed,  for  the  purpose  of  retaining  the  ui'ine,  an 
elastic  substance,  which  closes  the  urethra  constantly  by  an  unweary- 
ing physical  property.  Expulsion,  on  the  contrary,  occurring  only 
at  intervals,  demands  the  exercise  of  muscular  action,  that  action 
being  immediately  applied  to  the  elastic  agent  and  drawing  it  aside. 
It  is  by  means  of  this  interesting  provision  that  the  semen  and  the 
last  drops  of  urine  are  expelled  from  the  urethra  without  a  chance 
of  reflux  into  the  bladder,  and  that  the  urine  is  enabled  to  pass  freely 
along  its  canal  without  danger  of  entering  the  prostatic  or  ejacula- 
tory  ducts. 

The  Membranous  portion,  the  narrowest  part  of  the  canal,  is 
somewhat  less  than  an  inch  in  length.  It  is  situated  between  the 
two  layers  of  the  deep  perineal  fascia,  and  is  surrounded  by  the 
fan-like  expansions  of  the  upper  and  lower  segments  of  the  com- 
pressor urethrce  muscle  which  meet  at  the  raphe  along  its  upper  and 
lower  surface.  It  is  continuous  posteriorly  with  the  prostatic 
urethra,  and  anteriorly  with  the  spongy  portion  of  the  canal.  Its 
coverings  are  the  mucous  membrane,  elastic  fibrous  layer,  com- 
pressor urethras  muscle,  and  a  partial  sheath  from  the  deep  perineal 
fascia. 

The  Spongy  portion  forms  the  rest  of  the  extent  of  the  canal,  and 
is  lodged  in  the  corpus  spongiosum  from  its  commencement  at  the 
deep  perineal  fascia  to  the  meatus  urinarius.  It  is  narrowest  in  the 
body,  and  becomes  dilated  at  cither  extremity,  posteriorly  in  the 
bulb,  where  it  is  named  the  bulbous  portion,  and  anteriorly  in  the 
glans  penis,  where  it  forms  the  fossa  navicularis.  The  meatus 
urinarius  is  the  most  constricted  part  of  the  canal;  so  that  a  cathe- 
ter, which  will  enter  that  opening,  maybe  passed  freely  through  the" 
whole  extent  of  a  healthy  urethra.  Opening  into  the  bulbous  portion 
are  two  small  excretory  ducts  about  three  quarters  of  an  inch  in 
length,  which  may  be  traced  backwards,  between  the  coats  of  the 
urethra  and  the  bulb,  to  the  interval  between  the  two  layers  of  tlie 
deep  perineal  fascia,  where  they  ramify  in  two  small  lobulatcd  and 
somewhat  compressed  glands  of  about  the  size  of  peas.  These  are 
Cowper's  glands ;  they  are  situated  immediately  beneath  the  mem- 
branous portion  of  the  urethra,  and  are  enclosed  by  the  lower  seg- 
ment of  the  compressor  urethroe  muscle  so  as  to  bo  subject  to  mus- 
cular compression.  Upon  the  whole  of  the  internal  surface  of  the 
spongy  portion  of  the  urethra,  particularly  along  its  upper  wall,  are 
numerous  small  openings  or  lacuna;  which  arc  the  entrances  of 
mucous  glands  situated  in  the  submucous  cellular  tissue.  The 
openings  of  these  lacuna;  are  directed  forwards,  and  arc  liable  occa- 
sionally to  intercept  the  \)dmi  of  a  small  catheter  in  its  passage  into 
the  bladder.  At  about  an  inch  and  a  half  from  the  opening  of  the 
meatus  one  of  these  lacuna;  is  generally  found  much  larger  than  the 


TESTES.  539 

rest,  and  is  named  the  lacuna  magna.  In  a  beautiful  preparation 
of  this  lacuna,  made  by  Sir  Astley  Cooper,  the  extremity  of  the 
canal  presents  several  large  primary  ramifications. 

TESTES. 

The  testes  are  two  small  glandular  organs  suspended  from  the 
abdomen  by  the  spermatic  cords,  and  enclosed  in  an  external  tegu- 
mentary  covering,  the  scrotum. 

The  Scrotum  is  distinguished  into  two  lateral  halves  or  hemi- 
spheres by  a  raphe,  which  is  continued  anteriorly  along  the  under 
surface  of  the  penis,  and  posteriorly  along  the  middle  line  of  the 
perineum  to  the  anus.  Of  these  two  lateral  portions  the  left  is  some- 
what longer  than  the  right,  and  corresponds  with  the  greater  length 
of  the  spermatic  cord  on  the  left  side. 

The  scrotum  is  composed  of  two  layers,  the  integument  and  a 
proper  covering,  the  dartos  ;  the  integument  is  extremely  thin, 
transparent,  and  abundant,  and  beset  by  a  number  of  hairs  which 
issue  obliquely  fi'om  the  skin,  and  have  prominent  roots.  The  dartos 
is  a  thin  layer  of  a  peculiar  contractile  fibrous  tissue,  intermediate 
in  properties  between  muscular  fibre  and  elastic  tissue ;  it  forms  the 
proper  tunic  of  the  scrotum,  and  sends  inwards  a  distinct  septum 
(septum  scroti)  which  divides  it  into  two  cavities  for  the  two  testes. 
The  dartos  is  continuous  around  the  base  of  the  scrotum  with  the 
common  superficial  fascia  of  the  abdomen  and  perineum. 

The  Spermatic  cord  is  the  medium  of  communication  between  the 
testes  and  the  interior  of  the  abdomen ;  it  is  composed  of  arteries, 
veins,  lymphatics,  nerves,  the  excretory  duct  of  the  testicle  and  its 
proper  coverings.  It  commences  at  the  internal  abdominal  ring, 
where  the  vessels  of  which  it  is  composed  converge,  and  passes 
obliquely  along  the  spermatic  canal ;  the  cord  then  escapes  at  the 
external  abdominal  ring  and  descends  through  the  scrotum  to  the 
posterior  border  of  the  testicle.  The  left  cord  is  somewhat  longer 
than  the  right,  and  permits  the  left  testicle  to  reach  a  lower  level 
than  the  risrht. 

The  Arteries  of  the  spermatic  cord  are  the  spermatic  artery  from 
the  aorta ;  the  deferential  artery,  accompanying  the  vas  deferens, 
from  the  superior  vesical;  and  the  cremasteric  branch  from  the 
epigastric  artery.  The  spermatic  veins  form  a  plexus  which  con- 
stitutes the  chief  bulk  of  the  cord  ;  they  are  provided  with  valves  at 
short  intervals,  and  the  smaller  veins  have  a  peculiar  tendril-like 
arrangement  which  has  obtained  for  them  the  name  of  vasa  pampi- 
niformia.  The  lymphatics  are  of  large  size,  and  terminate  in  the 
lumbar  glands.  The  nerves  are  the  spermatic  plexus,  which  is 
derived  from  the  aortic  and  renal  plexus,  the  genital  branch  of  the 
genito-crural  nerve,  and  the  scrotal  branch  of  the  ilio-scrotal. 

The  Vas  deferens,  the  excretory  duct  of  the  testicle,  it  situated 
along  the  posterior  border  of  the  cord,  where  it  may  be  easily  dis- 
tinguished by  the  hard  and  cordy  sensation  which  it  communicates 


540 


COVEKINGS  OF  COED TESTIS. 


Fiff.  161.* 


to  the  fingers.     Its  parietes  are  very  thick  and  tough,  and  its  canal 

extremely  small  and  lined  by  the  mucous  membrane  continued  from 
the  urethra. 

The  Coverings  of  the  spermatic  cord  are  the  spermatic  fascia, 
cremaster  muscle,  and  fascia  propria.  The  spermatic  fascia  is  a 
prolongation  of  the  intercolumnar  fascia,  derived  from  the  borders 
of  the  external  abdominal  ring  during  the  descent  of  the  testicle  in 
the  foetus.  The  cremasteric  covering  (erythroid)  is  the  thin  mus- 
cular expansion  formed  by  the  spreading  out  of  the  fibres  of  the 
cremaster,  which  is  likewise  carried  down  by  the  testis  during  its 
descent.  The  fascia  propria  is  a  continuation  of  the  intundibiliform 
process  from  the  transversalis  fascia  which  immediately  invests  the 
vessels  of  the  cord,  and  is  also  obtained  during  the  descent  of  the 
testis. 

The  Testis  (testicle)  is  a  small  oblong  and  rounded  gland,  some- 
what compressed  upon  the  sides  and  behind,  and  suspended  in  the 
cavity  of  the  scrotum  by  the  spermatic  cord. 

Its  position  in  the  scrotum  is  oblique ;  so  that  the  upper  extremity 
is  directed  upwards  and  forwards,  and  a  little 
outwards;  the  lower,  downwards  and  back- 
wards, and  a  little  inwards ;  the  convex  sur- 
face looks  forwards  and  downwards,  and  the 
flattened  surface  to  which  the  cord  is  attached, 
backwards  and  upwards.  Lying  against  its 
outer  and  posterior  border  is  a  flattened  body 
which  follows  the  course  of  the  testicle,  and 
extends  from  its  upper  to  its  lower  extremity ; 
this  body  is  named,  from  its  relation  to  the 
testis,  epididymis  {s'fi  upon,  SiSufj^os  the  testicle) ; 
it  is  divided  into  a  central  part  or  body,  an 
upper  extremity  or  globus  major,  and  a  lower 
extremity,  globus  minor  (cauda)  epididymis. 
The  globus  major  is  situated  upon  the  upper 
end  of  the  testicle,  to  which  it  is  closely  adherent ;  the  globus  minor 
is  placed  at  its  lower  end,  is  attached  to  the  testis  by  cellular  tissue, 
and  curves  upwards,  to  become  continuous  with  the  vas  deferens. 
The  testis  is  invested  by  three  tunics — tunica  vaginalis,  tunica 
albuginea,  and  tunica  vasculosa ;  and  is  connected  to  the  inner  sur- 
face'of  the  dartos  by  a  large  quantity  of  extremely  loose  cellular 
tissue,  in  which  fat  is  never  deposited,  but  which  is  very  susceptible 
of  serous  infiltration. 


■*  A  transverse  section  of  the  testicle.  1.  The  cavity  of  the  tunica  vaginalis;  the 
most  external  layer  is  the  tunica  vaginalis  reflcxa  ;  and  that  in  contact  with  the  organ, 
the  tunica  vaginalis  propria.  2.  The  tunica  albuginea.  3.  The  mediastinum  testis, 
giving  off  numarous  fibrous  cords  in  a  radiated  direction  to  the  internal  surface  of  the 
tunica  albuginea.  The  cut  extremities  of  tlic  vessels  belowr  the  number  belong  to  the 
rete  testis  ;  and  tliose  above  to  tiie  artei'ies  and  veins  of  the  organ.  4.  The  tunica  vas- 
culosii,  or  pia  mater  testis.  .5.  One  of  the  lobules,  consisting  of  the  convolutions  of  the 
tubuli'seminiferi,  and  terminating  by  a  single  duct — the  vas  rectum.  Corresponding 
lobules  arc  seen  between  the  other  fibrous  cords  of  the  mediastinum.  6.  Section  of  the 
epididymis. 


STRUCTURE  OF  THE  TESTIS.  541 

The  Tunica  vaginalis  is  a  pouch  of  serous  membrane  derived* 
from  the  peritoneum  in  the  descent  of  the  testis,  and  afterwards 
obliterated  from  the  abdomen  to  within  a  short  distance  of  the  gland. 
Like  other  serous  coverings  it  is  a  shut  sac,  investing  the  organ  and 
thence  reflected  so  as  to  form  a  bag  around  its  circumference ;  hence 
it  is  divided  into  the  tunica  vaginalis  propria,  and  tunica  vaginalis 
rejlexa.  The  tunica  vaginalis  propria  covers  the  surface  of  the 
tunica  albuginea,  and  surrounds  the  epididymis,  connecting  it  to  the 
testis  by  means  of  a  distinct  duplicature.  The  tunica  vaginaUs  re- 
flexa  is  attached  by  its  external  surface,  through  the  medium  of  a 
quantity  of  loose  cellular  tissue,  to  the  inner  surface  of  the  dartos. 
Between  the  two  layers  is  the  smooth  surface  of  the  shut  sac,  moist- 
ened by  its  proper  secretion. 

The  Tunica  albuginea  (dura  mater  testis)  is  a  thick  fibrous  mem- 
brane of  a  bluish  white  colour,  and  the  proper  tunic  of  the  testicle. 
It  is  adherent  externally  to  the  tunica  vaginaHs  propria,  and  from 
the  union  of  a  serous  with  a  fibrous  membrane  is  considered  a  fibro- 
serous  membrane,  like  the  dura  mater  and  pericardium.  After  sur- 
rounding the  testicle,  the  tunica  albuginea  is  refllected  from  its  pos- 
terior border  into  the  interior  of  the  gland,  and  forms  a  projecting 
longitudinal  ridge,  which  is  called  the  mediastinum  testis  (corpus 
Highmorianum*)  from  which  numerous  fibrous  cords  (trabeculas, 
septula)  are  given  off",  to  be  inserted  into  the  inner  surface  of  the 
tunic.  The  mediastinum  serves  to  contain  the  vessels  and  ducts  of 
the  testicle  in  their  passage  into  the  substance  of  the  organ,  and  the 
fibrous  cords  are  admirably  fitted,  as  has  been  shown  by  Sir  Astley 
Cooper,  to  prevent  compression  of  the  gland.  If  a  transverse  section 
be  made  of  the  testis,  and  the  surface  of  the  mediastinum  examined, 
it  will  be  observed  that  the  blood-vessels  of  the  substance  of  the 
organ  are  situated  near  the  posterior  border  of  the  mediastinum, 
while  the  divided  ducts  of  the  rete  testis,  occupy  a  place  nearer  to 
the  free  margin. 

The  Tunica  vasculosa  (pia  mater  testis)  is  the  nutrient  membrane 
of  the  testis ;  it  is  situated  immediately  within  the  tunica  albuginea 
and  encloses  the  substance  of  the  gland,  sending  processes  inwards 
between  the  lobules,  in  the  same  manner  that  the  pia  mater  is  re- 
flected between  the  convolutions  of  the  brain. 

The  substance  of  the  testis  consists  of  numerous  conical  flattened 
lobules  (lobuli  testis),  the  bases  being  directed  towards  the  surface 
of  the  organ,  and  the  apices  towards  the  mediastinum.  Krause 
found  between  four  and  five  hundred  of  these  lobules  in  a  single 
testis.  Each  lobule  is  invested  by  a  distinct  sheath  formed  by  two 
layers,  one  being  derived  from  the  tunica  vasculosa,  the  other  from 
the  tunica  albuginea.  The  lobule  is  composed  of  one  or  several 
minute  tubuli,  iubuli  seminiferi,-\  exceedingly  convoluted,  anasto- 

*  Nathaniel  Higflimore,  a  physician  of  Oxford,  in  his  "Corporis  Humani  Disquisitio 
Anatomica,"  publislied  in  1051  :  he  considers  the  corpus  Hifrhnioiianum  as  a  duct 
formed  by  the  converg;ence  of  the  fibrous  cords,  which  he  mistakes  for  smaller  ducts. 

t  Lauth  estimates  the  wliolc  number  of  tubuli  seminiteri  in  each  testis,  at  840,  and 
their  average  lengtli  at  2  feet  3  inches.  According  to  this  calculation,  the  whole  length 
of  the  tubuli  seniinifcri  would  be  1890  feet. 


542 


EPIDIDYMIS. 


•  mosing  frequently  with  each  other  near  to  their  extremities,  termi- 
nating in  loops  or  in  free  c^cal  ends,  and  of  the  same  diameter 
(_|_  Lauth)  throughout.  The  tubuli  seminiferi  are  of  a  bright  yel- 
low colour ;  they  become  less  convoluted  in  the  apices  of  the  lobules, 
and  terminate  by  forming  between  twenty  and  thirty  small  straight 
ducts  of  about  twice  the  diameter  of  the  tubuli  seminiferi, — the  vasa 
recta.  The  vasa  recta  enter  the  substance  of  the  mediastinum,  and 
terminate  in  from  seven  to  thirteen  ducts,  smaller  in  diameter  than 
the  vasa  recta.  These  ducts  pursue  a  waving  course  from  below 
upwards  through  the  fibrous  tissue  of  the  mediastinum ;  they  com- 
municate freely  with  each  other,  and  constitute  the  7'ete  testis.  At 
the  upper  extremity  of  the  mediastinum,  the  ducts  of  the  rete  testis 
terminate  in  from  nine  to  thirty  small  ducts,  the  vasa  ejferentia,* 
which  form  by  their  convolutions  a  series  of  conical  masses,  the 
coni  vasculosi ;  from  the  bases  of  these  cones  tubes  of  larger  size 
proceed,  which  constitute  by  their  complex  convolutions  the  body 
of  the  epididymis.  The  tubes  become  gradually  larger  towards  the 
lower  end  of  the  epididymis,  and  terminate  in  a  single  large  and 
convoluted  duct,  the  vas  deferens. 

The  Epididytnis  is  formed  by  the  convolutions  of  the  excretory 
seminal  ducts,  externally  to  the  testis,  pre- 
viously to  their  termination  in  the  vas  deferens. 
The  more  numerous  convolutions  and  the  ag- 
gregation of  the  coni  vasculosi  at  the  upper  end 
of  the  organ  constitute  the  globus  major  ;  the 
continuation  of  the  convolutions  downwards 
is  the  body ;  and  the  smaller  number  of  con- 
volutions of  the  single  tube  at  the  lower  ex- 
tremity, the  globus  minor.  The  tubuli  are 
connected  together  by  a  very  delicate  cel- 
lular tissue,  and  are  enclosed  by  the  tunica 
vaginalis. 

A  small  convoluted  duct,  of  variable  length, 
is  generally  connected  with  the  duct  of  the  epi- 
didymis immediately  before  the  commencement 
of  the  vas  deferens.  This  is  the  vasculum 
aberrans  of  Haller ;  it  is  attached  to  the  epi- 
didymis by  the  cellular  tissue  in  which  that 
body  is  enveloped.  Sometimes  it  becomes 
dilated  towards  its  extremity,  but  more  fre- 
quently retains  the  same  diameter  throughout. 


Fiff.  I62.t 


*  Each  vas  deferens  witli  its  cone  measures,  according'  to  Lautli,  about  8  inches. 
The  entire  Icnjrth  of  tlic  tubes  composing  the  epidid)'mis,  according  to  the  same 
authority,  is  about  21  feet. 

t  Anatomy  of  tin;  testis.  1,1.  The  tunica  albupfinca.  9,2.  The  mediastinum  testis. 
3,  .3.  The  lobuli  testis.  4,  4.  Tiic  vasa  recta.  r>,  5.  The  rete  testis.  6.  The  vasa 
cfTcrentia,  of  which  five  only  are  lepresented  in  tliis  dingrain.  7.  TIjc  coni  vasculosi, 
constituting  the  globiis  ma  jor  of  tiie  epididymis.  8.  Tlie  body  of  the  epididymis.  9. 
The  globus  minor  of  the  epididymis.  10,  The  vas  deferens.  11.  The  vasculum 
aberrans. 


FEMALE  PELVIS.  543 

The  Fas  deferens  may  be  traced  upwards  in  the  course  of  the 
seminal  fluid,  from  the  globus  minor  of  the  epididymis  along  the  pos- 
terior part  of  the  spermatic  cord,  and  along  the  spermatic  canal  to 
the  internal  abdominal  ring.  From  the  ring  it  is  reflected  inwards  to 
the  side  of  the  fundus  of  the  bladder,  and  descends  along  its  posterior 
surface,  crossing  the  direction  of  the  ureter,  to  the  inner  border  of  the 
vesicula  seminalis.  In  this  situation  it  becomes  somewhat  larger  in 
size  and  convoluted,  and  terminates  at  the  base  of  the  prostate  gland, 
by  uniting  with  the  duct  of  the  vesicula  seminalis  and  constituting  the 
ejaculatory  duct.  The  ejaculatory  duct,  which  is  thus  formed  by 
the  junction  of  the  duct  of  the  vesicula  seminaUs  with  the  vas 
deferens,  passes  forwards  to  the  anterior  extremity  of  the  veru- 
montanum,  where  it  terminates  by  opening  into  the  prostatic 
urethra. 


FEMALE    PELVIS. 

The  peculiarities  of  the  form  of  the  female  pelvis  have  already 
been  examined  with  the  anatomy  of  the  bones.  Its  lining  bounda- 
ries are  the  same  with  those  of  the  male.  The  contents  are,  the 
bladder,  vagina,  uterus  with  its  appendages,  and  the  rectum.  Some 
portion  of  the  small  intestines  also  occupy  the  upper  part  of  its 
cavity. 

The  Bladder  is  in  relation  with  the  os  pubis  in  front,  with  the 
uterus  behind,  from  which  it  is  usually  separated  by  a  convolution 
of  small  intestine,  and  with  the  neck  of  the  uterus,  and  with  the 
vagina  beneath.  The  form  of  the  female  bladder  corresponds  with 
that  of  the  pelvis,  being  broad  from  side  to  side,  and  often  bulging 
more  on  one  side  than  on  the  other.  This  is  particularly  evident 
after  frequent  parturition.  The  coats  of  the  bladder  are  the  same 
as  those  of  the  male. 

The  Urethra  is  about  an  inch  and  a  half  in  length,  and  is  lodged 
m  the  upper  wall  of  the  vagina,  in  its  course  downwards  and  for- 
wards, beneath  the  arch  of  the  os  pubis,  to  the  meatus  urinarius. 
It  is  lined  by  mucous  membrane,  which  is  disposed  in  longitudinal 
folds,  and  is  continuous  internally  with  that  of  the  bladder,  and  ex- 
ternally with  the  vulva ;  the  mucous  membrane  is  surrounded  by  a 
proper  coat  of  elastic  tissue,  to  which  the  muscular  fibres  of  the 
detrusor  urinae  are  attached.  It  is  to  this  tissue  that  is  due  the  re- 
markable dilatability  of  the  female  urethra,  and  its  speedy  return  to 
its  original  diameter.  The  meatus  is  encircled  by  a  ring  of  fibrous 
tissue,  which  pi'events  it  from  distending  with  the  same  facility  as 
the  rest  of  the  canal ;  hence  it  is  sometimes  advantageous  in  per- 
forming this  operation  to  divide  its  margin  slightly  with  the  knife. 

Vagina. — The  Vagina  is  a  membranous  canal,  leading  from  the 
vulva  to  the  uterus,  and  corresponding  in  direction  with  the  axis  of 
the  outlet  of  the  pelvis.  It  is  constricted  at  its  commencement,  but 
near  the  uterus  becomes  considerably  dilated ;  and  is  closed  by  the 
contact  of  the  anterior  with  the  posterior  wall.     Its  length  is  very 


544  VAGINA UTERUS. 

variable ;  but  it  is  always  longer  upon  the  posterior  than  upon  the 
anterior  wall,  the  former  being  usually  about  five  or  six  inches  in 
length,  and  the  latter  four  or  five.  It  is  inserted  into  the  cervix  of 
the  uterus,  which  projects  into  the  upper  extremity  of  the  canal. 

In  Structure  the  vagina  is  composed  of  a  mucous  lining,  a  layer 
of  erectile  tissue,  and  an  external  tunic  of  a  cellulo-jibrous  structure, 
resembling  the  dartos  of  the  scrotum.  The  upper  fourth  of  the 
posterior  wall  of  the  vagina  is  covered,  on  its  pelvic  surface,  by  the 
peritoneum;  while  in  front  the  peritoneum  is  reflected  from  the 
upper  part  of  the  cervix  of  the  uterus  to  the  posterior  surface  of  the 
bladder.  On  each  side  it  gives  attachment  superiorly  to  the  broad 
ligaments  of  the  uterus  ;  and  inferiorly  to  the  pelvic  fascia,  and  to 
the  levatores  ani. 

The  Mucous  membrane  presents  a  number  of  transverse  papill(B 
or  rugcB  upon  its  upper  and  lower  surfaces,  which  extend  outwards 
on  each  side  from  a  middle  rafhe.  The  transverse  papillae  and 
raphe,  are  more  apparent  upon  the  upper  than  upon  the  lower  sur- 
face, and  the  two  raphe  are  called  the  columns  of  the  vagina.  The 
mucous  membrane  is  covered  by  a  thin  cuticular  epithelium,  which 
is  continued  from  the  labia,  and  terminates  by  a  fringed  border  at 
about  the  middle  of  the  cervix  uteri. 

The  Middle  or  erectile  laijer  consists  of  erectile  tissue  enclosed 
between  two  layers  of  fibrous  membrane ;  this  layer  is  thickest  near 
the  commencement  of  the  vagina,  and  becomes  gradually  thinner 
as  it  approaches  the  uterus. 

The  External,  or  dartoid  layer  of  the  vagina,  serves  to  connect 
it  to  the  surrounding  viscera.  Thus,  it  is  very  closely  adherent  to 
the  under  surface  of  the  bladder,  and  drags  that  organ  down  with 
it  in  prolapsus  uteri.  To  the  rectum  it  is  less  closely  connected,  and 
that  intestine  is  therefore  less  frequently  affected  in  prolapsus. 

UTERUS. 

The  Uterus  is  a  flattened  organ  of  a  pyriform  shape,  having  the 
base  directed  upwards  and  forwards,  and  the  apex  downwards  and 
backwards  in  the  line  of  the  axis  of  the  inlet  of  the  pelvis,  and 
forming  a  considerable  angle  with  the  course  of  the  vagina.  It  is 
convex  on  its  posterior  surface,  and  somewhat  flattened  upon  its 
anterior  aspect.  In  the  unimpregnated  state  it  is  about  three  inches 
in  length,  two  in  breadth  across  its  broadest  part,  and  one  in  thick- 
ness, and  is  divided  into  fundus,  body,  cervix,  and  os  uteri.  At  the 
period  of  puberty  the  uterus  weighs  about  one  ounce  and  a  half; 
after  parturition  from  two  to  three  ounces ;  and  at  the  ninth  month 
of  utcro-gcstation  from  two  to  four  pounds. 

The  Fundus  and  bodij  arc  enclosed  in  a  duplicature  of  peritoneum, 
which  is  connected  with  the  two  sides  of  the  pelvis,  and  forms  a 
transverse  septum  between  the  bladder  and  rectum.  The  folds 
formed  by  this  duplicature  of  peritoneum  on  either  side  of  the 
organ  arc  the  broad  ligaments  of  the  ulonis.     The  cervix  is  the 


CONTENTS  OF  FEMALE  PELVIS, 


545 


lower  portion  of  the  organ;  it  is  distinguished  from  the  body  by  a 
well-marked  constriction ;  to  its  upper  part  is  attached  the  upper 
extremity  of  the  vagina,  and  at  its  extremity  is  an  opening  which 
is  nearly  round  in  the  virgin,  and  transverse  after  parturition — the 
OS  2<^erf— bounded  before  and  behind  by  two  labia;  the  anterior 
labium  being  the  most  thick,  and  the  posterior  somewhat  the  longest. 

Fig.  163  * 


The  opening  of  the  os  uteri  is  of  considerable  size,  and  is  named 
the  orificium  uteri  externum;  the  canal  then  becomes  narrowed, 
and  at  the  upper  end  of  the  cervix  is  constricted  into  a  smaller 
opening — the  orificium  intemum.f  At  this  point  the  canal  of  the 
cervix  expands  into  the  shallow  triangular  cavity  of  the  uterus,  the 
inferior  angle  corresponding  with  the  orificium  internum,  and  the 
two  superior  angles,  which  are  funnel-shaped   and  represent  the 

*  A  side  view  of  the  viscera  of  the  female  pelvis.  1.  The  symphysis  pubis ;  to  the 
upper  part  of  which  the  tendon  of  the  rectus  muscle  is  attached.  2.  The  abdominal 
parietes.  3.  The  collection  of  fat,  forming-  the  projection  of  the  mons  Veneris.  4.  The 
urinary  bladder.  5.  The  entrance  of  the  left  ureter.  6.  The  canal  of  the  urethra, 
converted  into  a  mere  fissure  by  the  contraction  of  its  walls.  7.  The  meatus  urinarius. 
8.  The  clitoris,  with  its  prEeputium,  divided  through  the  middle.  9.  The  left  nympha. 
10.  The  left  labium  majus.  11.  The  meatus  of  the  vagina,  narrowed  by  the  contrac- 
tion of  its  sphincter.  12.  The  canal  of  the  vagina,  upon  which  the  transverse  rugse 
are  apparent,  13.  The  thick  wall  of  separation  between  the  base  of  the  bladder  and 
the  vagina.  14,  The  wall  of  separation  between  the  vagina  and  the  rectum.  15.  The 
perineum.  1 6.  The  os  uteri.  17.  Its  cervix.  18.  The  fundus  uteri.  The  cavitas  uteri 
is  seen  along  the  centre  of  the  organ.  10,  The  rectum,  sliowing  the  disposition  of  its 
mucous  membrane,  20.  The  anus,  21,  The  upper  part  of  the  rectum,  invested  by 
the  peritoneum.  22.  Tlie  recto-uterine  fold  of  the  peritoneum.  Just  above  the  figure. 
23.  The  utcro-vesical  fold.  24,  The  reflection  of  the  peritoneum,  from  the  apex  of 
the  bladder,  upon  the  trachus  to  the  internal  surface  of  the  abdominal  parietes,  25. 
The  last  lumbar  vertebra.     26.  The  sacrum.     27,  Tlio  coccyx. 

t  The  orificium  internum  is  not  unfrequcntly  obliterated  in  old  persons.  Indeed, 
this  obliteration  is  so  common,  as  to  have  induced  Mayer  to  regard  it  as  normal. 

69 


546 


STKUCTURE  OF  UTERUS. 


original  bicornute  condition  of  the  organ,  with  the  commencement 
of  the  Fallopian  tubes.  In  the  canal  of  the  cervix  uteri  are  two 
or  three  longitudinal  folds  to  which  numerous  oblique  folds  converge 
so  as  to  give  the  idea  of  branches  from  the  stem  of  a  tree ;  hence 
this  appearance  has  been  denominated  the  arhor  vitce  uterina.  Be- 
tween these  folds,  and  around  the  os  uteri,  are  numerous  mucous 
follicles.  It  is  the  closure  of  the  mouth  of  one  of  these  follicles, 
and  the  subsequent  distension  of  the  follicle  with  its  proper  secre- 
tion, that  occasions  those  vesicular  appearances  so  often  noticed 
within  the  mouth  and  cervix  of  the  uterus,  called  the  ovula  of 
JVahoth. 

Structure. — The  uterus  is  composed  of  three  tunics ;  of  an  external 
or  serous  coat  derived  from  the  peritoneum,  which  constitutes  the 
duplicatures  on  each  side  of  the  organ  called  the  broad  ligaments ; 
of  a  middle  or  muscular  coat,  which  gives  thickness  and  bulk  to  the 
uterus  ;  and  of  an  internal  or  mucous  membrane,  which  lines  its  in- 
terior, and  is  continuous  on  the  one  hand  with  the  mucous  lining  of 
the  Fallopian  tubes,  and  on  the  other  with  that  of  the  vagina.  In 
the  unimpregnated  state  the  muscular  coat  is  exceedingly  condensed 
in  texture,  offers  considerable  resistance  to  section  with  the  scalpel, 
and  appears  to  be  composed  of  white  fibres  inextricably  interlaced 
and  mingled  with  blood-vessels.  In  the  impregnated  uterus  the 
fibres  are  of  large  size  and  distinct,  and  are  disposed  in  two  layers, 
superficial  and  deep.  The  suferjicial  layer  consists  of  fibres  which 
pursue  a  vertical  direction,  some  being  longitudinal  and  others 
oblique.  The  longitudinal  fibres  are  found  principally  upon  the 
middle  line,  forming  a  thin  plane  upon  the  anterior  and  posterior 
face  of  the  organ  and  upon  its  fundus.  The  oblique  fibres  occupy 
chiefly  the  sides  and  fundus.  At  the  angles  of  the  uterus  the  fibres 
of  the  superficial  layer  are  continued  outwards  upon  the  Fallopian 
tubes,  and  into  the  round  ligaments  and  the  ligaments  of  the  ovaries. 
The  deej)  layer  consists  of  two  hollow  cones  of  circular  fibres  having 
their  apex  at  the  openings  of  the  Fallopian  tubes,  and  by  their  bases 
intermingling  with  each  other  on  the  body  of  the  organ.  These 
fibres  are  continuous  with  the  deep  muscular  layer  of  the  Fallopiaii 
tubes,  and  indicate  the  primitive  formation  of  the  uterus  by  the 
blending  of  these  two  canals.  Around  the  cervix  uteri  the  muscular 
fibres  assume  a  circular  form  interlacing  with  and  crossing  each 
other  at  acute  angles.  The  mucous  membrane  is  provided  with  a 
columnar  ciliated  epithelium,  which  extends  from  the  middle  of  the 
cervix  uteri  to  the  extremities  of  the  Fallopian  tubes. 

Vessels  and  Nerves. — The  Arteries  of  the  uterus  are  the  uterine 
from  the  internal  iliac,  and  the  spermatic  from  the  aorta.  The 
veins  are  very  large  and  remarkable  ;  in  the  impregnated  uterus 
they  are  called  sinuses,  and  consist  of  canals  channeled  through  the 
substance  of  the  organ,  being  merely  lined  by  the  internal  membrane 
of  the  veins.  They  terminate  on  each  side  of  the  uterus  in  the 
uterine  plexuses.     The  lymphatics  terminate  in  the  lumbar  glands. 


FALLOPIAN  TUBES OVARIES.  547 

The  Nerves  are  derived  from  the  hypogastric  and  spermatic 
plexuses,  and  from  the  sacral  plexus. 

The  Jlppendages  of  the  uterus  are  enclosed  by  the  lateral  dupli- 
catures  of  peritoneum,  called  the  broad  ligaments.  They  are  the 
Fallopian  tubes  and  ovaries. 

FALLOPIAJf  TUBES. 

The  Fallopian*  tubes  or  oviducts,  the  uterine  trumpets  of  the 
French  writers,  are  situated  in  the  upper  border  of  the  broad  liga- 
ments, and  are  connected  with  the  superior  angles  of  the  uterus. 
They  are  somewhat  trumpet-shaped,  being  much  smaller  at  the 
uterine  than  at  the  free  extremity,  and  narrower  in  the  middle  than 
at  either  end.  Each  tube  is  about  four  or  five  inches  in  length,  and 
more  or  less  flexuous  in  its  course.  The  canal  of  the  Fallopian 
tube  is  exceedingly  minute,  its  inner  extremity  opens  by  means  of 
the  ostium  uterinum  into  the  upper  angle  of  the  cavity  of  the  uterus, 
and  the  opposite  end  into  the  cavity  of  the  peritoneum.  The  free 
or  expanded  extremity  of  the  Fallopian  tube  presents  a  double  and 
sometimes  a  triple  series  of  small  processes  or  fringes  which  sur- 
round the  margin  of  the  trumpet  or  funnel-shaped  opening,  the 
ostium  abdominale.  This  fringe-like  appendage  to  the  end  of  the 
tube  has  gained  for  it  the  appellation  of  the  fimbriated  extremity ; 
and  the  remarkable  manner  in  which  this  circular  fringe  applies 
itself  to  the  surface  of  the  ovary  during  sexual  excitement,  the 
additional  title  of  morsus  diaboli.  One  of  these  processes  longer 
than  the  rest,  or,  according  to  Cruveilhier  a  distinct  ligamentous 
cord,  is  attached  to  the  distal  end  of  the  ovary,  and  serves  to  guide 
the  tube  in  its  seizure  of  that  organ. 

The  Fallopian  tube  is  composed  of  three  tunics,  an  external  and 
loose  investment  derived  from  the  peritoneum ;  a  middle  or  muscular 
coat  consisting  of  circular  [internal]  and  longitudinal  [external] 
fibres,  continuous  with  those  of  the  uterus ;  and  an  internal  or  lining 
mucous  membrane  which  is  continuous  on  the  one  hand  with  the 
mucous  membrane  of  the  uterus,  and  at  the  opposite  extremity 
with  the  peritoneum.  In  the  minute  canal  of  the  tube  the  mucous 
membrane  is  thrown  into  longitudinal  folds  or  rugas,  which  indicate 
the  adaptation  of  the  tube  to  dilatation. 

OVARIES. 

The  Ovaries  are  two  oblong  flattened  and  oval  bodies  of  a  whitish 
colour,  situated  in  the  posterior  layer  of  peritoneum  of  the  broad 
ligaments.     They  are  connected  to  the  upper  angles  of  the  uterus 

*  Gabriel  Fallopius,  a  nobleman  of  Modcna,  was  one  of  the  founders  of  modern 
anatomy.  He  was  Professor  at  Ferrara,  then  at  Pisa,  and  afterwards  succeeded  Vesa- 
lius  at  Padua.  His  principal  observations  are  collected  in  a  work,  "  Observationes 
Anatomicoe,"  which  he  published  in  1561. 


548  ♦  EXTERNAL  OEGANS. 

at  each  side  by  means  of  a  rounded  cord,  consisting  chiefly  of  mus- 
cular fibres  derived  from  the  uterus, — the  ligament  of  the  ovary. 

In  structure  the  ovary  is  composed  of  a  cellulo-fibrous  parenchyma 
or  stroma,  traversed  by  blood-vessels,  and  enclosed  in  a  capsule 
consistincr  of  three  layers ;  a  vascular  layer,  which  is  situated  most 
internally  and  sends  processes  inwards  towards  the  interior  of  the 
oro-an;  a  middle  or  fibrous  layer  of  considerable  density  and  an 
external  investment  of  peritoneum.  In  the  cells  of  the  stroma  of  the 
ovary  the  small  vesicles  or  ovisacs  of  the  future  ova,  the  Graafian 
vesicles,  as  they  have  been  termed,  are  developed.  They  are  usu- 
ally about  fifteen  fully  formed  Graafian  vesicles  in  each  ovary ;  but 
Dr.  Martin  Barry  has  shown  that  countless  numbers  of  microscopic 
ovisacs  exist  in  the  parenchyma  of  the  organ,  and  that  very  few 
out  of  these  are  perfected  so  as  to  produce  ova. 

After  conception  a  yellow  spot,  the  corpus  luteum,  is  found  in  one 
or  both  ovaries-  The  corpus  luteum  is  a  globular  mass  of  yellow, 
spongy  tissue,  traversed  by  white  cellular  bands,  and  containing  in 
its  centre  a  small  cavity,  more  or  less  obUterated,  which  was  origi- 
nally occupied  by  the  ovum.  The  interior  of  the  cavity  is  lined  by 
a  puckered  membrane,  the  remains  of  the  ovisac.  In  recent  corpora 
lutea  the  opening  by  which  the  ovum  escaped  from  the  ovisac 
through  the  capsule  of  the  ovary  is  distinctly  visible ;  when  closed, 
a  small  cicatrix  may  be  seen  upon  the  surface  of  the  ovary  in  the 
situation  of  the  opening.  A  similar  appearance  to  the  preceding, 
but  of  smaller  size,  and  without  a  central  cavity,  is  sometimes  met 
with  in  the  ovaries  of  the  virgin, — this  is  ^  false  coripus  luteum. 

Vessels  and  Nerves. — The  Arteries  of  the  ovaries  are  the  sper- 
matic.    Its  nerves  are  derived  from  the  spermatic  plexus. 

The  Round  ligaments  are  two  muscular  and  fibrous  cords  situated 
between  the  layers  of  the  broad  ligaments,  and  extending  from  the 
upper  angles  of  the  uterus,  and  along  the  spermatic  canals  to  the 
labia  majora,  in  which  they  are  lost.  They  are  accompanied  by  a 
small  artery,  by  several  filaments  of  the  spermatic  plexus  of  nerves, 
and  by  a  plexus  of  veins.  The  latter  occasionally  become  varicose, 
and  form  a  small  tumour  at  the  external  abdominal  ring  which  has 
been  mistaken  for  inguinal  hernia.  The  round  ligaments  serve  to 
retain  the  uterus  in  its  proper  position  in  the  pelvis,  and  during  utero- 
gestation  to  draw  the  anterior  surface  of  the  organ  against  the 
abdominal  parietes. 

EXTERNAL  ORGANS  OF  GENERATION. 

The  female  organs  of  generation  arc  divided  into  the  internal  and 
external;  the  internal  arc  contained  within  the  pelvis,  and  have  been 
already  dcscriljcd, — they  arc  the  vagina,  uterus,  ovaries,  and  Fallo- 
pian tubes.  The  external  organs  are  the  mons  Veneris,  labia  ma- 
jora, labia  minora,  clitoris,  meatus  urinarius,  and  the  opening  of  the 
vagina. 

The  Mons  Veneris  is  the  eminence  of  integument,  situated  upon 


LABIA CLITORIS.  549 

the  front  of  the  os  pubis.     Its  cellular  tissue  is  loaded  with  adipose 
substance,  and  the  surface  covered  with  hairs. 

The  Labia  majora  axe  two  large  longitudinal  folds  of  integument, 
consisting  of  fat  and  loose  cellular  tissue.  They  enclose  an  elliptical 
fissure,  the  common  urino-sexual  opening  or  vulca.  The  vulva  re- 
ceives the  inferior  opening  of  the  urethra  and  vagina,  and  is  bounded 
anteriorly  by  the  commissura  superior,  and  posteriorly  by  the  com- 
missura  inferior.  Stretching  across  the  posterior  commissure  is  a 
small  transverse  fold,  the  frcenulum  labior'um  or  fourchette,  which  is 
ruptured  during  parturition,  and  immediately  within  this  fold  is  a 
small  cavity,  the  fossa  navicular'is.  The  breadth  of  the  perineum  is 
measured  from  the  posterior  commissure  to  the  margin  of  the  anus, 
and  is  usually  not  more  than  an  inch  across.  The  external  surface 
of  the  labia  is  covered  with  hairs ;  the  inner  surface  is  smooth,  and 
lined  by  mucous  membrane,  which  contains  a  number  of  sebaceous 
foUicles,  and  is  covered  by  a  thin  cuticular  epithelium.  The  use  of 
the  labia  majora  is  to  favour  the  extension  of  the  vulva  during  par- 
turition ;  for,  in  the  passage  of  the  head  of  the  fcetus  the  labia  are 
completely  unfolded  and  effaced. 

The  Labia  minora,  or  nymphcE  are  two  smaller  folds  situated 
within  the  labia  majora.  Superiorly  they  are  divided  into  two  pro- 
cesses, which  surrounds  the  glans  clitoridis,  the  superior  fold  form- 
ing the  prseputium  clitoridis,  and  the  inferior  its  frgenulum.  Infe- 
riorly,  they  diminish  gradually  in  size,  and  are  lost  on  the  sides  of 
the  opening  of  the  vagina.  The  nymphce  consist  of  mucous  mem- 
brane, covered  by  a  thin  cuticular  epithelium.  They  are  provided 
with  a  number  of  sebaceous  folhcles,  and  contain,  in  their  interior,  a 
layer  of  erectile  tissue. 

The  Clitoris  is  a  small  elongated  organ  situated  in  front  of  the  os 
pubis,  and  supported  by  a  suspensory  ligament.  It  is  formed  by  a 
small  body,  which  is  analogous  to  the  corpus  cavernosum  of  the 
penis,  and,  like  it,  arises  from  the  ramus  of  the  os  pubis  and  ischium 
on  each  side,  by  two  crura.  The  extremity  of  the  clitoris  is  called 
its  glans.  It  is  composed  of  erectile  tissue,  enclosed  in  a  dense 
layer  of  fibrous  membrane,  and  is  susceptible  of  erection.  Like  the 
penis,  it  is  provided  with  two  small  muscles,  the  erectores  clitoridis. 

At  about  an  inch  beneath  the  clitoris  is  the  entrance  of  the  vagina, 
an  elliptical  opening,  marked  by  a  projecting  margin.  The  entrance 
to  the  vagina  is  closed  in  the  virgin  by  a  membrane  of  a  semilunar 
form,  which  is  stretched  across  the  opening  ;  this  is  the  hymen. 
Sometimes  the  membraiie  forms  a  complete  septum,  and  gives  rise 
to  great  inconvenience  by  preventing  the  escape  of  the  menstrual 
effusion.  It  is  then  called  an  impejforate  hymen.  The  hymen  must 
not  be  considered  a  necessary  accompaniment  to  virginity,  for  its 
existence  is  very  uncertain.  When  present  it  assumes  a  variety  of 
appearances  :  it  may  be  a  membranous  fringe,  with  a  round  open- 
ing in  the  centre,  or  a  semilunar  fold,  leaving  an  opening  in  front ; 
or  a  transverse  septum,  having  an  opening  both  in  front  and  behind ; 
or  a  vertical  band  with  an  opening  at  either  side. 


550  MAJIMARY  GLAN^DS. 

The  rupture  of  the  hymen  or  its  rudimentary  existence,  gives  rise 
to  the  appearance  of  a  fringe  of  papillae  around  the  opening  of  the 
vagina :  these  are  called  cai-uncu/ce  myrtiformes. 

"The  triangular  smooth  surface  between  the  clitoris  and  the  en- 
trance of  the  vagina,  which  is  bounded  on  each  side  by  the  upper 
portions  of  the  nymphae,  is  the  vestibule. 

At  the  upper  angle  of  the  vagina  is  an  elevation  formed  by  the 
projection  of  the  upper  wall  of  the  canal,  and  analogous  to  the  bulb 
of  the  urethra  of  the  male :  and  immediately  in  front  of  this  tubercle, 
and  surrounded  by  it,  is  the  opening  of  the  urethra,  the  meatus 
urinarius. 

MAMMARY  GLANDS. 

The  MammcB  are  situated  in  the  pectoral  region ;  and  are  separated 
from  the  pectoralis  major  muscle  by  a  thin  layer  of  superficial  fascia. 
They  exist  in  the  male  as  well  as  in  the  female,  but  in  a  rudimentaiy 
state,  unless  excited  into  growth  by  some  peculiar  action,  such  as 
the  loss  or  atrophy  of  the  testes. 

Their  base  is  somewhat  elliptical,  the  long  diameter  correspond- 
ing with  the  direction  of  the  fibres  of  the  pectoralis  major  muscle. 
The  left  mamma  is  generally  a  little  larger  than  the  right. 

Near  the  centre  of  the  convexity  of  each  mamma  is  a  small  pro- 
jection of  the  integument,  called  the  ?iipple,  which  is  surrounded  by 
an  areola  having  a  coloured  tint.  In  the  female  before  impregna- 
tion, the  colour  of  the  areola  is  a  delicate  pink ;  after  impregnation 
it  assumes  a  brownish  hue  which  deepens  in  colour  as  pregnancy 
advances;  and  after  the  birth  of  a  child,  the  brownish  tint  continues 
through  life. 

The  areola  is  furnished  with  a  considerable  number  of  sehaceous 
follicles,  which  secrete  a  peculiar  fatty  substance  for  the  protection 
of  the  delicate  integument  around  the  nipple.  During  suckling  these 
follicles  are  very  much  increased  in  size,  and  have  the  appearance 
of  small  pimples  projecting  from  the  skin.  At  this  period  they 
serve  by  their  increased  secretion  to  defend  the  nipple  and  areola 
from  the  excoriating  action  of  the  saliva  of  the  infant. 

In  Structure,  the  mamma  is  a  conglomerate  gland,  and  consists 
of  lobes,  which  are  held  together  by  a  dense  and  firm  cellular  tissue; 
the  lobes  are  composed  of  lobules;  and  the  lobules,  of  minute  cascal 
vesicles,  the  ultimate  terminations  of  the  excretory  ducts. 

The  excretory  ducts  (tubuli  lactiferi),  from  ten  to  fifteen  in 
number,  commence  by  small  openings  at  the  apex  of  the  nipple, 
and  pass  inwards,  parallel  with  each  other,  towards  the  central 
part  of  the  gland,  where  they  form  dilatations  (ampulla)  and  give 
off  numerous  branches  to  ramify  through  the  gland  to  their  ultimate 
terminations  in  the  minute  lobules. 

The  ducts  and  cmcal  vesicles  are  lined  throughout  by  a  mucous 
membrane,  which  is  continuous  at  the  apex  of  the  nipple  with  the 
integument. 


NERVES  OF  MAMM^.  551 

In  the  nipple  the  excretory  ducts  are  surrounded  by  a  tissue  ana- 
logous to  the  dartos  of  the  scrotum,  to  which  the  power  of  erectility 
of  the  nipple  seems  due.  There  is  no  appearance  of  any  structure 
resembhng  erectile  tissue. 

Vessels  and  Nerves. — The  mammce  are  supplied  with  arteries 
from  the  thoracic  branches  of  the  axillary,  from  the  intercostals, 
and  from  the  internal  mammary. 

The  Lymphatics  follow  the  border  of  the  pectoralis  major  to  the 
axillary  glands. 

The  Nerves  are  derived  from  the  thoracic  and  intercostals. 


CHAPTER   XL 

ANATOMY  OF  THE  FCETUS. 

The  medium  weight  of  a  child  of  the  full  period,  at  birth,  is  seven 
pounds  ;  and  its  length  nineteen  inches.  The  head  is  of  large  size, 
and  lengthened  from  before  backwards ;  the  face  small.  The  upper 
extremities  are  greatly  developed,  and  the  thorax  expanded  and  full. 
The  upper  part  of  the  abdomen  is  large,  from  the  great  size  of  the 
liver;  the  lower  part  is  small  and  conical.  And  the  lower  extremi- 
ties are  very  small  in  proportion  to  the  rest  of  the  body.  The 
external  genital  organs  are  very  large,  and  fully  developed. 

Osseous  System. — The  developement  of  the  osseous  system  has 
been  treated  of  in  the  first  Chapter.  The  ligamentous  system  pre- 
sents no  peculiarity  deserving  of  remark. 

Muscular  System. — The  muscles  of  the  foetus  at  birth  are  large 
and  fully  formed.  They  are  of  a  lighter  colour  than  those  of  the 
adult,  and  of  a  softer  texture.  The  transverse  strise  upon  the  fibres 
of  animal  life  are  not  distinguishable  until  the  sixth  month  of  foetal 
life. 

Vascular  System. — The  circulating  system  presents  several 
pecuUarites;  Istly,  In  the  heart;  there  is  a  communication  between 
the  two  auricles  by  means  of  the  foramen  ovale.  2dly,  In  the  arte- 
rial system ;  there  is  a  communication  between  the  pulmonary 
artery  and  descending  aorta,  by  means  of  a  large  trunk — the 
ductus  arteriosus.  3dly,  Also  in  the  arterial  system  ;  the  internal 
iliac  arteries,  under  the  name  of  hypogastric  and  umbilical,  are 
continued  from  the  foetus  to  the  placenta,  to  which  they  return 
the  blood  which  has  circulated  in  the  system  of  the  foetus.  4thly, 
In  the  venous  system;  there  is  a  communication  between  the 
umbilical  vein  and  the  inferior  vena  cava,  called  the  ductus  venosus. 

F(ETAL  CIRCULATION. 

The  pure  blood  is  brought  from  the  placenta  by  the  umbilical 
vein.  The  umbilical  vein  passes  through  the  umbilicus  and  enters 
the  liver,  where  it  divides  into  several  branches,  which  may  be 
arranged  under  three  heads  : — Istly,  two  or  three  of  which  are  dis- 
tributed to  the  left  lobe.  2d]y,  A  single  branch  which  communicates 
with  the  ])ortal  vein  in  the  transverse  fissure,  and  supplies  the  right 
lobe.      3dly,  A  large  branch,  the  ductus  venosus,  which  passes 


FffiTAL  CIRCULATIOX, 


553 


Fiff.  1G'1.« 


o    o 


directly  backwards  and  joins  the 
inferior  cava.  In  the  inferior 
cava  the  pure  blood  becomes 
mixed  with  that  which  is  return- 
ing from  the  lower  extremities, 
and  is  carried  through  the  right 
auricle,  guided  by  the  Eustachian 
valve,  and  through  the  foramen 
ovale  into  the  left  auricle.  From 
the  left  auricle  it  passes  into  the 
left  ventricle,  and  from  the  left 
ventricle  into  the  aorta,  whence 
it  is  distributed,  by  means  of  the 
carotid  and  subclavian  arteries, 
principally  to  the  head  and  upper 
extremities.  From  the  head  and 
upper  extremities,  the  impure  blood 
is  returned  by  the  superior  vena 
cava  to  the  right  auricle.  From 
the  right  auricle,  it  is  propelled 
into  the  right  ventricle;  and 
from  the  right  ventricle  into 
the  pulmonary  artery.  In  the 
adult,  the  blood  would  now  be 
circulated  through  the  lungs,  and 
oxygenated ;  but  in  the  foetus  the 
lungs  are  solid,  and  almost  imper- 
vious. Only  a  small  quantity  of 
the  blood  passes  therefore  into  the 
lungs;  the  greater  part  rushes 
through  the  ductus  arteriosus,  into 
the  commencement  of  the  descend- 
ing aorta. 

*  The  fetal  circulation.  1.  The  umbilical  cord,  consisting  of  the  umbilical  vein 
and  two  umbilical  arteries ;  proceeding  from  the  placenta  (2).  3.  The  umbilical  vein 
dividing  into  three  branches ;  two  (4,  4)  to  be  distributed  to  the  liver  ;  and  one  (5),  the 
ductus  venosus,  which  enters  the  inferior  vena  cava  (6).  7.  The  portal  vein  return- 
ing the  blood  from  the  intestines,  and  uniting  with  the  right  hepatic  branch.  8. 
The  right  auricle  ;  the  course  of  the  blood  is  denoted  by  the  arrow,  proceeding  from  8 
to  9,  the  left  auricle.  10.  The  left  ventricle  ;  the  blood  following  the  arrow  to  the  arch 
of  the  aorta  (11),  to  be  distributed  through  the  branches  given  off  by  the  arch  to  the 
head  and  upper  extremities.  The  arrows  12  and  1.3,  represent  the  return  of  the  blood 
from  the  head  and  upper  extremities  through  the  jugular  and  subclavian  veins,  to  the 
superior  vena  cava  (14),  to  the  right  auricle  (8),  and  in  the  course  of  the  arrow  through 
the  right  ventricle  (15),  to  the  pulmonary  artery  (16).  17.  The  ductus  arteriosus, 
which  appears  to  be  a  proper  continuation  of  the  pulmonary  artery,  the  offsets  at  each 
side  are  the  right  and  left  pulmonary  artery  cut  off;  these  are  of  extremely  small  size 
as  compared  with  the  ductus  arteriosus.  Tiie  ductus  arteriosus  joins  the  descending 
aorta  (18,  18),  which  divides  into  the  common  iliacs,  and  these  into  tlic  internal  iliacs, 
which  become  the  umbilical  arteries  (19),  and  return  the  blood  along  the  umbilical 
cord  to  the  placenta;  while  the  other  divisions,  the  external  iliacs  (20),  are  continued 
into  the  lower  extremities.  The  arrows  at  the  termination  of  these  vessels  mark  the 
return  of  the  venous  blood  by  the  veins  to  the  inferior  cava. 

70 


\J  u 


554  FCKTAL  CIRCULATION. 

Passing  along  the  aorta,  a  small  quantity  of  the  impure  blood  is 
distributed  by  the  external  iliac  arteries  to  the  lower  extremities ; 
the  greater  portion  enters  the  internal  iliacs,  and  is  carried  on- 
wards by  the  side  of  the  bladder,  and  upwards  along  the  anterior 
wall  of  the  abdomen,  and  through  the  umbilicus,  under  the  name  of 
umhUical  arteries,  to  the  placenta,  to  which  they  return  the  blood 
that  has  been  circulated  through  the  system  of  the  foetus. 

From  a  careful  consideration  of  this  circulation,  we  shall  per- 
ceive— 1st.  That  the  pure  blood  from  the  placenta  is  distributed  in 
considerable  quantity  to  the  liver,  before  entering  the  general  circu- 
lation. Hence  arises  the  abundant  nutrition  of  that  organ,  and  its 
enormous  size  in  comparison  with  the  other  viscera. 

2dly.  That  the  right  auricle  is  the  scene  of  meeting  of  a  double 
current ;  the  one  coming  from  the  inferior  cava,  the  other  from  the 
superior,  and  that  they  must  cross  each  other  in  their  respective 
course.  How  this  crossing  is  effected  the  theorist  will  wonder;  not 
so  the  practical  anatomist ;  for  a  cursory  examination  of  the  foetal 
heart  will  show,  1.  That  the  direction  of  entrance  of  the  two  vessels 
is  so  opposite,  that  they  may  discharge  their  currents  through  the 
same  cavity  without  admixture.  2.  That  the  inferior  cava  opens 
almost  directly  into  the  left  auricle.  3.  That  by  the  aid  of  the 
Eustachian  valve,  the  current  in  the  inferior  cava  will  be  almost 
entirely  excluded  from  the  right  ventricle. 

3dly.  That  the  blood  which  circulates  through  the  arch  of  the 
aorta  comes  directly  from  the  placenta ;  and,  although  mixed  with 
impure  blood  of  the  inferior  cava,  yet  is  propelled  in  so  great 
abundance  to  the  head  and  upper  extremities,  as  to  provide  for  the 
increased  nutrition  of  those  important  parts,  and  prepare  them,  by 
their  greater  size  and  developement,  for  the  functions  which  they 
are  required  to  perform  at  the  instant  of  birth. 

4thly.  That  the  blood  circulating  in  the  descending  aorta  is  very 
impure,  being  obtained  principally  from  the  returning  current  in  the 
superior  cava ;  a  small  quantity  only  being  derived  from  the  left 
ventricle.  Yet  is  it  from  this  impure  blood  that  the  nutrition  of  the 
lower  extremities  is  provided.  Hence  we  are  not  surprised  at  their 
insignificant  developement  at  birth,  while  we  admire  the  providence 
of  nature,  that  directs  the  nutrient  current  in  abundance  to  the 
organs  of  sense,  of  prehension,  and  of  deglutition,  so  necessary 
even  at  the  instant  of  birth  to  the  safety  and  welfare  of  the  crea- 
ture. 

After  birth,  the  foramen  ovale  becomes  gradually  closed  by  a 
membranous  layer,  which  is  developed  from  the  margins  of  the 
opening  from  below  upwards,  and  completely  separates  the  two 
auricles.  The  situation  of  the  foramen  is  seen  in  the  adult  heart, 
upon  the  septum  auriculorum,  and  is  called  the  fossa  ovalis ;  the 
projecting  margin  of  the  opening  forms  the  annulus  ovalis. 

As  soon  as  the  lungs  have  become  inflated  by  the  first  spasmodic 
act  of  inspiration,  the  blood  of  the  pulmonary  artery  rushes  through 
its  right  and  loft  branches  into  the  lungs,  to  be  returned  to  the  left 


ORGANS  OF  SENSE — TIIYKOID  GLAND.  555 

auricle  by  the  palmonary  veins.  Thus  the  pulmonary  circulation 
is  established.  Then  the  ductus  arteriosus  contracts,  and  degene- 
rates into  an  impervious  fibrous  cord,  serving  in  after  life  merely 
as  a  bond  of  union  between  the  left  pulmonary  artery  and  the  con- 
cavity of  the  arch  of  the  aorta. 

The  current  through  the  umbilical  cord  being  arrested,  the 
umbilical  arteries  likewise  contract  and  become  impervious,  and 
degenerate  into  the  umbilical  ligaments  of  the  bladder. 

The  Umbilical  vein  and  ductus  venosus,  also  deprived  of  their 
circulating  current,  become  reduced  to  fibrous  cords,  the  former 
forming  the  round  ligament  of  the  liver,  and  the  latter  a  fibrous 
band  which  may  be  traced  along  the  fissure  for  the  ductus  venosus 
to  the  inferior  vena  cava. 

Nervous  System. — The  brain  is  very  soft,  almost  pulpy,  and  has 
a  reddish  tint  throughout:  the  difference  between  the  white  and 
gray  substance  is  not  well  marked.  The  nerves  are  firm  and  well 
developed. 

ORGANS  OF  SENSE. 

Eye. — The  eyeballs  are  of  large  size  and  well  developed  at  birth. 
The  pupil  is  closed  by  a  vascular  membrane  called  the  memhrana 
pupillaris,  which  disappears  at  about  the  seventh  month.  Some- 
times it  remains  permanently,  and  produces  blindness.  It  consists 
of  two  thin  membranous  layers,  between  which  the  ciliary  arteries 
are  prolonged  from  the  edge  of  the  iris,  and  form  arches  by  re- 
turning to  it  again,  without  anastomosing  with  those  of  the  opposite 
side. 

The  removal  of  the  membrane  takes  place  by  the  contraction  of 
their  loops  towards  the  edge  of  the  pupil.  The  capsule  of  the  lens 
is  extremely  vascular. 

Ear. — The  ear  is  remarkable  for  its  early  developement ;  the 
labyrinth  and  ossicula  auditus  are  ossified  at  an  early  period,  and 
the  latter  are  completely  formed  before  birth.  The  only  parts  re- 
maining incomplete  are  the  mastoid  cells,  and  the  meatus  auditorius. 
The  membrani  tympani  in  the  foetal  head  is  very  obhqae,  occupying 
almost  the  basilar  surface  of  the  skull ;  hence  probably  arises  a  de- 
ficient acuteness  in  the  perception  of  sound.  It  is  also  extremely 
vascular. 

JVose. — The  sense  of  smell  is  very  imperfect  in  the  infant,  as  may 
be  inferred  from  the  small  capacity  of  the  nasal  fossss,  and  the 
non-developement  of  the  ethmoid,  sphenoid,  frontal,  and  maxillary 
sinuses. 

THYROID  GLAND. 

The  Thyroid  gland  is  of  a  large  size  in  the  foetus,  and  is  developed 
by  two  lateral  halves,  which  approach  and  become  connected  at 


556 


THYMUS  GLAND. 


the  middle  line  so  as  to  constitute  a  single  gland.     It  is  doubtful 
whether  it  performs  any  especial  function  in  fcetal  life. 


THYMUS  GLAND. 

The  Thymus  gland*  consists  "  of  a  thoracic  and  a  cervical  por- 
tion on  each  side.  The  former  is  situated  in  the  anterior  mediasti- 
num, and  the  latter  is  placed  in  the  neck  just  above  the  first  bone  of 
the  sternum,  and  behind  the  sterno-hyoidei  and  sterno-thyroidei 
muscles."  It  extends  upwards  from  the  fourth  rib  as  high  as  the 
thyroid  gland,  resting  upon  the  pericardium,  and  separated  from  the 
arch  of  the  aorta  and  great  vessels  by  the  thoracic  fascia  in  the 
chest,  and  lying  on  each  side  of  the  trachea  in  the  neck. 

Although  described  usually  as  a  single  gland,  it  consists  actually 
of  two  lateral,  almost  symmetrical  glands,  connected  with  each 
other  by  cellular  tissue  only,  and  having  no  structural  communica- 
tion ;    they  may  therefore  be 
^'?- 1^^'''  "properly  called  a  right  and 

left  thymus  gland." 

Between  the  second  and 
third  months  of  embryo  exist- 
ence, the  thymus  is  so  small  as 
to  be  only  "  just  perceptible ;" 
and  continues  gradually  in- 
creasing with  the  growth  of 
the  foetus  until  the  seventh.  At 
the  eighth  month  it  is  large ; 
but,  during  the  ninth,  it  under- 
goes a  sudden  change,  assumes 
a  greatly  increased  size,  and 
at  birth  weighs  240  grains. 
After  birth  it  continues  to  en- 
large until  the  expiration  of  the  first  year,  when  it  ceases  to  grow, 
and  gradually  diminishes,  until  at  puberty  it  has  almost  disappeared. 
The  thymus  is  a  conglomerate  gland,  being  composed  of  lobules 
disposed  in  a  spiral  form  round  a  central  cavity.  The  lobules  are 
held  together  by  a  firm  cellular  tissue  ("  reticulated"),  and  the  entire 
gland  is  enclosed  in  a  coarse  cellular  capsule. 

The  Lobules  are  very  numerous,  and  vary  in  size  from  that  of  the 

*  In  the  description  of  this  gland  I  Iiave  adliered  closely  to  the  history  of  it  given 
by  our  great  authority  on  this  subject,  Sir  Astlcy  Cooper,  in  his  beautiful  monograph 
"On  the  Anatomy  of  the  Tiiymus  Gland,"  1832, 

t  A  section  of  the  tliymus  gland  at  the  eiglith  montii,  showing  its  anatomy.  This 
figure,  and  tiio  succeeding,  were  drawn  from  two  of  Sir  Astley  Cooper's  beautiful  pre- 
parations, with  the  kind  permission  of  their  possessor.  The  references  were  made  by 
Sir  Astlcy's  own  hand.  1.  The  cervical  portions  of  the  gland  ;  the  independence  of 
the  two  lateral  glands  is  well  marked.  2.  Secretory  cells  seen  u])on  the  cut  surface  of 
the  section  ;  these  are  observed  in  all  parts  of  the  secti(jn.  3,  3.  The  pores  or  openings 
of  the  secretory  cells  and  pouches,  they  are  seen  covering  the  whole  internal  surface  of 
the  great  central  cavity  or  reservoir.  The  continuity  of  the  reservoir  in  the  lower  or 
thoracic  portion  of  tlie  gland,  with  the  cervical  portion,  is  seen  in  the  figure. 


STRUCTURE  OF  THYMUS. 


557 


Fig.  166.' 


head  of  a  pin  to  a  moderate-sized  pea.  Each  lobule  contains  in 
its  interior  a  small  cavity,  or  "  secretory  cell,'''  and  several  of  these 
cells  open  into  a  small  "  pouch"  which  is  situated  at  their  base,  and 
leads  to  the  central  cavity,  the  "  reservoir  of  the  thymus." 

The  Reservoir  is  lined  in  its  interior  by  a  vascular  mucous  mem- 
brane, which  is  raised  into  ridges  by  a  layer  of 
ligamentous  bands  situated  beneath  it.  The 
ligamentous  bands  proceed  in  various  directions, 
and  encircle  the  open  mouths  (pores)  of  the 
secretory  cells  and  pouches.  This  ligamentous 
layer  serves  to  keep  the  lobules  together,  and 
prevent  the  injurious  distension  of  the  cavity. 

When  either  gland  is  carefully  unravelled  by 
removing  the  cellular  capsule  and  vessels,  and 
dissecting  away  the  reticulated  cellular  tissue, 
which  retains  the  lobules  in  contact,  the  reservoir, 
from  being  folded  in  a  serpentine  manner  upon 
itself,  admits  of  being  drawn  out  into  a  length- 
ened tubular  cord,-\  around  which  the  lobules  are 
clustered  in  a  spiral  manner,  and  resemble  knots 
upon  a  cord,  or  a  string  of  beads. 

The  reservoir,  pouches,  and  cells,  contain  a 
white  fluid  "like  chyle,"  or  "like  cream,  but  with 
a  small  admixture  of  red  globules." 

In  an  examination  of  the  thymic  fluid  which  I 
lately  made,  with  a  Powell  microscope  magnify- 
ing 500  times  linear  measure,  I  observed  that 
the  corpuscles  were  very  numerous,  smaller  than 
the  blood  corpuscles,  globular  and  oval  in  form, 
irregular  in  outline,  variable  in  size,  and  pro- 
vided with  a  small  central  nucleus. 

In  the  human  fcetus  this  fluid  has  been  found 
by  Sir  Astley  in  too  small  proportion  to  be  sub- 
mitted to  chemical  analysis.  But  the  thymic  fluid  of  the  fcetal  calf, 
which  exists  in  great  abundance,  gave  the  following  analytical 
results: — one  hundred  parts  of  the  fluid  contained  sixteen  parts  of 
solid  matter,  which  consisted  of, 

Incipient  fibrine, 

Albumen, 

Mucus,  and  muco-extractive  matter, 

Muriate  and  phosphate  of  potass, 

Phosphate  of  soda, 

Phosphoric  acid,  a  trace. J 

*  The  course  and  termination  of  the  "  absorbent  ducts"  of  the  thymus  of  the  calf; 
from  one  of  Sir  Astley  Cooper's  preparations.  1.  The  two  internal  jugular  veins.  2. 
The  superior  vena  cava.  3.  The  thoracic  duct,  dividing  into  two  branches,  which  re- 
unite previously  to  tlicir  termination  in  the  root  of  the  left  jugular  vein.  4.  The  two 
thymic  ducts;  that  on  the  left  side  opens  into  the  thoracic  duct,  and  that  on  the  right 
into  the  root  of  the  right  jugular  vein. 

t  See  the  beautiful  plates  in  Sir  Astley  Cooper's  work. 

\  This  analysis  was  conducted  by  Dr.  Dowler  of  Richmond. 


558  FCETAL  LUXGS  A>-D  HEART. 

The  Arteries  of  the  thymus  gland  are  derived  from  the  internal 
mammary,  and  from  the  superior  and  inferior  thyroid. 

The  Veins  terminate  in  the  left  vena  innominata,  and  some  small 
branches  in  the  thyroid  veins. 

The  Ae?'ue5  are  very  minute,  and  are  derived  chiefly  through  the 
internal  mammary  plexus,  from  the  superior  thoracic  ganglion  of 
the  sympathetic.  Sir  Astley  Cooper  has  also  seen  a  branch  from 
the  junction  of  the  pneumogastric  and  sympathetic  pass  to  the  side 
of  the  gland. 

The  Lynrphatics  terminate  in  the  general  union  of  the  lymphatic 
vessels  at  the  junction  of  the  internal  jugular  and  subclavian  veins. 
Sir  Astley  Cooper  has  injected  them  only  once  in  the  human  foetus, 
but  in  the  calf  he  finds  two  large  lymphatic  ducts,  which  commence 
in  the  upper  extremities  of  the  glands,  and  pass  downwards,  to  ter- 
minate at  the  junction  of  the  jugular  and  subclavian  vein  at  each 
side.  These  vessels  he  considers  the  "  absorbent  duds  of  the  glands ; 
'  thymic  ducts ;'  they  are  the  carriers  of  the  fluid  from  the  thymus 
into  the  veins." 

Sir  Astley  Cooper  concludes  his  anatomical  description  of  this 
gland  with  the  following  interesting  physiological  observations  : — 

"As  the  thymus  secretes  all  the  parts  of  the  blood,  viz.  albumen, 
fibrine,  and  particles,  is  it  not  probable  that  the  gland  is  designed  to 
prepare  a  fluid  well  fitted  for  the  foetal  growth  and  nourishment 
from  the  blood  of  the  mother,  before  the  birth  of  the  foetus,  and, 
consequently,  before  chyle  is  formed  from  food  ? — and  this  process 
continues  for  a  short  time  after  birth,  the  quantity  of  fluid  secreted 
from  the  thymus  gradually  declining  as  that  of  chyhfication  becomes 
perfectly  established." 

FffiTAL  LUNGS. 

The  Lungs  previously  to  the  act  of  inspiration,  are  dense  and 
solid  in  structure,  and  of  a  deep  red  colour ;  their  specific  gravity 
greater  than  water,  in  which  they  sink  to  the  bottom,  whereas  lung 
which  has  respired  will  float  upon  that  fluid.  The  specific  gravity 
is,  however,  no  test  of  the  real  weight  of  the  lung ;  the  respired 
lung  being  actually  heavier  than  the  foetal.  Thus  the  weight  of  the 
foetal  lung,  at  about  the  middle  period  of  uterine  life,  is  to  the  weight 
of  the  body  as  1  to  60.*  But,  after  respiration,  the  relative  weight 
of  the  lung  to  the  entire  body  as  1  to  30. 

FCETAL    HEART. 

The  Heart  of  the  foetus  is  large  in  proportion  to  the  size  of  the 
body ;  it  is  also  developed  very  early,  representing  at  first  a  simple 
vessel,  and  undergoing  various  degrees  of  complication  until  it  ar- 
rives at  the  compound  character  which  it  presents  after  birth.    The 

*  Cruvclhicr.  yVnatoiuio  Descriptive,  vol.  ii.  p.  021. 


VISCERA  OP  THE  AEDOME?f.  559 

two  ventricles  form,  at  one  period,  a  single  cavity,  which  is  after- 
wards divided  into  two  by  the  septum  ventriculorum.  The  two 
auricles  communicate  up  to  the  moment  of  birth,  the  septum  being 
incomplete,  and  leaving  a  large  opening  between  them,  \\iq  foramen 
ovale  (foramen  of  Botal.)* 

The  Ductus  arteriosus  is  another  peculiarity  of  the  foetus  con- 
nected with  the  heart ;  it  is  a  communication  between  the  pulmo- 
nary artery  and  the  aorta.  It  degenerates  into  a  fibrous  cord  after 
birth,  from  the  double  cause  of  a  diversion  in  the  current  of  the 
blood  towards  the  lungs,  and  from  the  pressure  of  the  left  bronchus, 
caused  by  its  distension  with  air. 


VISCERA  OF  THE  ABDOMEIV. 

At  an  early  period  of  uterine  life,  and  sometimes  at  the  period  of 
birth,  as  I  have  twice  observed,  in  the  imperfectly  developed  foetus 
two  minute  fibrous  threads  may  be  seen,  passing  from  the  umbilicus 
to  the  mesentery.  These  are  the  remains  of  the  omphalo-mesen- 
teric  vessels. 

The  Omplialo-mesenteric  are  the  first  developed  vessels  of  the 
germ :  they  ramify  upon  the  vesicula  umbilicalis,  or  yolk-bag,  and 
supply  the  newly  formed  alimentary  canal  of  the  embryo.  From 
them,  as  from  a  centre,  the  general  circulating  system  is  produced. 
After  the  establishment  of  the  placental  circulation  they  cease  to 
carry  blood,  and  dwindle  to  the  size  of  mere  threads,  which  may  be 
easily  demonstrated  in  the  early  periods  of  uterine  life;  but  are 
completely  removed,  except  under  peculiar  circumstances,  at  a  later 
period. 

The  Stomach  is  of  small  size,  and  the  great  extremity  but  little 
developed.  It  is  also  more  vertical  in  direction  the  earlier  it  may 
be  examined,  a  position  that  would  seem  due  to  the  enormous  mag- 
nitude of  the  liver,  and  particularly  of  its  left  lobe. 

The  Appendix  vermiformis  cceci  is  long  and  of  large  size,  and  is 
continued  directly  from  the  central  part  of  the  cul-de-sac  of  the 
caecum,  of  which  it  appears  to  be  a  constricted  continuation.  This 
is  the  character  of  the  appendix  cseci  in  the  higher  qaadrumana. 

The  large  intestines  are  filled  with  a  dark  green  viscous  secre- 
tion called  meconiuyn  ((j/^xwv,  poppy),  from  its  resemblance  to  the  in- 
spissated juice  of  the  poppy. 

The  Pancreas  is  comparatively  larger  in  the  fcetus  than  in  the 
adult. 

The  Spleen  is  comparatively  smaller  in  the  fcetus  than  in  the 
adult. 

*  Leonard  Botal,  of  Piedmont,  was  tlie  first  of  the  moderns  who  Cfave  an  account  of 
this  opcnino^,  in  a  worlv  publislied  in  15G5.  His  description  is  very  imperfect.  The 
foramen  was  well  known  to  Galen, 


560  FCETAL  LIVEK  AKi)  KIDNEYS. 


FCETAL  LIVER. 

"The  Liver  is  the  first  formed  organ  in  the  embryo.  It  is  deve- 
loped from  the  alimentary  canal,  and,  at  about  the  third  week,  fills 
the  whole  abdomen,  and  is  one  half  the  weight  of  the  entire  embryo. 
At  the  fourth  month  the  liver  is  of  immense  size  in  proportion  to  the 
bulk  of  the  foetus.  At  birth  it  is  of  very  large  size  and  occupies  the 
whole  upper  part  of  the  abdomen.  The  left  lobe  is  as  large  as  the 
right,  and  the  falciform  ligament  corresponds  with  the  middle  line 
of  the  body.  The  liver  diminishes  rapidly  after  birth,  probably  from 
the  obliteration  of  the  umbilical  vein. 


KIDNEYS  AND  SUPRA-RENAL  CAPSULES. 

The  Kidneys  present  a  lobulated  appearance  in  the  foetus,  which 
is  the  permanent  type  amongst  some  animals,  as  in  the  bear,  the 
otter,  and  cetacea. 

The  Supra-renal  capsules  are  organs  which  appear,  from  their 
early  and  considerable  developement,  to  belong  especially  to  the 
economy  of  the  foetus.  They  are  distinctly  formed  at  the  second 
month  of  embryonic  life,  and  are  greater  in  size  and  weight  than 
the  kidneys.  At  the  fourth  month  they  are  equalled  in  bulk  by  the 
kidneys,  and  at  birth  they  are  about  one-third  less  than  those  organs. 


VISCERA  OF  THE  PELVIS. 

The  Bladder  in  the  foetus  is  long  and  conical,  and  is  situated  alto- 
gether above  the  upper  border  of  the  os  pubis,  which  is  as  yet  small 
and  undeveloped.  It  is,  indeed,  an  abdominal  viscus,  and  is  con- 
nected superiorly  with  a  fibrous  cord,  called  the  urachus,  of  which 
it  appears  to  be  an  expansion. 

The  Urachus  is  continued  upwards  to  the  umbilicus,  and  becomes 
connected  with  the  umbiUcal  cord.  In  animals  it  is  a  pervious  duct, 
and  is  continuous  with  one  of  the  membranes  of  the  embryo — the 
allantois.  It  has  been  found  pervious  in  the  human  foetus,  and  the 
urine  has  been  passed  through  the  umbilicus.  Calculous  concretions 
have  also  been  found  in  its  course. 

The  Uterus,  in  the  early  periods  of  embryonic  existence,  appears 
to  be  bifid,  from  the  large  size  of  the  Fallopian  tubes,  and  the  small 
developement  of  the  body  of  the  organ.  At  the  end  of  the  fourth 
month  the  body  assumes  a  larger  bulk,  and  the  bifid  appearance  is 
lost.  The  cervix  uteri  in  the  foetus  is  larger  than  the  body  of  the 
organ. 

The  Ovaries  are  situated,  like  the  testicles,  in  the  lumbar  region, 
near  to  the  kidneys,  and  descend  from  thence  gradually  into  the 
pelvis. 


561 


TESTES. 


The  Testicles  in  the  embryo  are  situated  in  the  lumbar  regions, 
immediately  in  front  of  and  somewhat  below  the  kidneys.  They 
have  connected  with  them  inferiorly  a  peculiar  structure  which 
assists  in  their  descent,  and  is  called  the  gubernaculum  testis. 

The  Gubernaculum  is  a  soft  and  conical  cord  composed  of  cellular 
tissue  containing  in  its  cells  a  gelatiniform  fluid.  In  the  abdomen  it 
lies  in  front  of  the  psoas  muscle,  and  passes  along  the  spermatic 
canal  which  it  serves  to  distend  for  the  passage  of  the  testis.  It  is 
attached  by  its  superior  and  larger  extremity  to  the  lower  end  of 
the  testis  and  epididymis,  and  by  the  inferior  extremity  to  the  bottom 
of  the  scrotum.  The  gubernaculum  is  surrounded  by  a  thin  layer 
of  muscular  fibres,  the  cremaster,  which  pass  upwards  upon  this 
body  to  be  attached  to  the  testis.  Inferiorly  the  muscular  fibres 
divide  into  three  processes  which,  according  to  Mr.  Curling,*  are 
thus  attached  : — "  The  external  and  broadest  is  connected  to  Pou- 
part's  ligament  in  the  inguinal  canal ;  the  middle  forms  a  lengthened 
band,  which  escapes  at  the  external  abdominal  ring,  and  descends 
to  the  bottom  of  the  scrotum,  where  it  joins  the  dartos  ;  the  internal 
passes  in  the  direction  inwards,  and  has  a  firm  attachment  to  the 
OS  pubis  and  sheath  of  the  rectus  muscle.  Besides  these  a  number 
of  muscular  fibres  are  reflected  from  the  internal  oblique  on  the 
front  of  the  gubernaculum." 


Fig.  167.+ 


Fig.  168.t 


*  See  an  excellent  paper  "  On  the  Structure  of  the  Gubernaculum,"  ifcc.  by  Mr.  Cur- 
ling, Lecturer  on  Morbid  Anatomy  in  the  London  Hospital,  in  the  Lancet,  vol.  ii. 
1840-41,  p.  70. 

t  A  diagram  illustrating  the  descent  of  the  testis.  1.  The  testis.  2.  The  epididy- 
mis.  3,3.  The  peritoneum.  4.  The  pouch  formed  around  the  testis  by  the  peritoneum. 
5.  The  pubic  portion  of  the  cremaster  attached  to  tiie  lower  part  of  the  testis.  6.  The 
portion  of  the  cremaster  attaclied  to  Pou  part's  ligament.  The  mode  of  eversion  of  the 
cremaster  is  shown  by  these  lines.  7.  The  gubernaculum,  attached  to  the  bottom  of 
the  scrotum,  and  becoming  shortened  by  the  contraction  of  the  muscular  fibres  which 
surround  it.     8,  8.  The  cavity  of  the  scroluin.     9.  The  peritoneal  cavity. 

X  In  this  figure  the  testis  has  completed  its  descent.  The  gubernaculum  is  shortened 
to  its  utmost,  and  the  cremaster  is  completely  everted.  The  pouch  of  peritoneum  above 
the  testis  is  compressed  so  as  to  form  a  tubular  canal.  1.  A  dotted  line  marks  the 
point  at  which  the  tunica  vaginalis  will  terminate  superiorly ;  and  the  figure  2  its 
cavity.-    3.  The  peritoneal  cavity. 

71 


562  DESCENT  OF  THE  TESTICLE. 

The  Descent  of  the  testicle  is  very  gradual  and  progressive. 
Between  the  fifth  and  sixth  month  it  has  reached  the  lower  part  of 
the  psoas  muscle,  and  during  the  seventh  it  makes  its  way  through 
the  spermatic  canal,  and  descends  into  the  scrotum. 

While  situated  in  the  lumbar  region,  the  testis  and  gubernaculum 
are  placed  behind  the  peritoneum,  by  which  they  are  invested  upon 
their  anterior  surface  and  sides.  As  they  descend,  the  investing 
peritoneum  is  carried  downwards  with  the  testis  into  the  scrotum, 
forming  a  lengthened  pouch  which  by  its  upper  extremity  opens 
into  the  cavity  of  the  peritoneum.  The  upper  part  of  this  pouch 
being  compressed  by  the  spermatic  canal  is  gradually  obliterated, 
the  obhteration  extending  downwards  along  the  spermatic  cord 
nearly  to  the  testis.  That  portion  of  the  peritoneum  which  imme- 
diately surrounds  the  testis  is,  by  the  above  process,  cut  off  from  its 
continuity  with  the  peritoneum,  and  is  termed  the  tunica  vaginalis ; 
and  as  this  membrane  must  be  obviously  a  shut  sac,  one  portion  of 
it  investing  the  testis,  and  the  other  being  reflected  so  as  to  form  a 
loose  bag  around  it,  its  two  portions  have  received  the  appellations 
of  tunica  vaginalis  propria,  and  tunica  vaginalis  reflexa. 

The  descent  of  the  testis  is  effected  by  means  of  the  traction  of  the 
muscle  of  the  gubernaculum  (cremaster).  "  The  fibres,"  writes  Mr. 
Curling,*  "  proceeding  from  Poupart's  ligament  and  the  obliquus 
internus,  tend  to  guide  the  gland  into  the  inguinal  canal ;  those 
attached  to  the  os  pubis,  to  draw  it  below  the  abdominal  ring  ;  and 
the  process  descending  to  the  scrotum,  to  direct  it  to  its  final  des- 
tination." During  the  descent  "  the  muscle  of  the  testis  is  gra- 
dually everted,  until,  when  the  transition  is  completed,  it  forms  a 
muscular  envelope  external  to  the  process  of  peritoneum,  which 
surrounds  the  gland  and  the  front  of  the  cord."  "  The  mass  com- 
posing the  central  part  of  the  gubernaculum,  which  is  so  soft,  lax, 
and  yielding  as  in  every  way  to  facilitate  these  changes,  becomes 
gradually  diffused,  and,  after  the  arrival  of  the  testicle  in  the 
scrotum,  contributes  to  form  the  loose  cellular  tissue  which  after- 
wards exists  so  abundantly  in  this  part."  The  attachment  of  the 
gubernaculum  to  the  bottom  of  the  scrotum  is  indicated  throughout 
life  by  distinct  traces. 

*  Loc.  cit. 


INDEX. 


Abdomen,  490 
Abdominal  regions,  490 
Abdominal  ring,  189,  249 
Abductor  oculi,  149 
Acetabulum,  87 
Acini,  516 
Adductor  oculi,  149 
Air-cells,  488 
Albino,  446 

Alcock,  Dr.,  researches  of,  398 
Alimentary  canal,  495 
Allantois,  559 
Amphi-arthrosis,  100 
Ampulla,  458 
AmygdalsB,  497 
Andersch,  notice  of,  393 
Annulus  ovalis,  472 
Antihelix,  450 
Antitragus,  450 
Antrum  of  Highmore,  46 

pylori,  500 
Anus,  506,  510 
Aorta,  abdominal,  263 

arch,  262 

ascending,  261 

thoracic,  263 
Aortic  sinuses,  260 
Aponeurosis,  129 
Apophysis,  21 

Apparatus  ligamentosus  colli,  96 
Appendices  epiploicae,  494 
Appendix  vermiformis,  502,  559 
Aqua  labyrinthi,  461 
Aquseductus  cochlese,  459 
vestibuli,  457 
Aqueduct  of  Sylvius,  373 
Aqueous  humour,  444 
Arachnoid  membrane,  365,  383 
Arantius,  notice  of,  475 
Arbor  vitae,  376 

uterina,  546 
Arch,  femoral,  257 

palmar,  superficial,  297 
Arcifovm  fibres,  381 
Areola,  550 

Arnold,  Frederick,  researches,  427 
Arteries. 

General  anatomy,  261 
structure,  262 


Arteries — continued. 

anastomotica  femor,  317 

magna,  292 
aorta,  263 

articularcs  genti,  318 
auricular  anterior,  275 
posterior,  274 
axillary,  288 
basilar,  284 
brachial,  291 
bronchial,  297 
bulbosi,  310 
calcanean,  323 
carotid  common,  268 
external,  269 
internal,  278 
carpal  ulnar,  296 
radial,  294 
cavernosi,  310 
centralis  retince,  281 
cerebellar  inferior,  284 
superior,  285 
cerebral,  281 
cervicalis  anterior,  287 
posterior,  287 
choroidean,  281 
ciliary,  280 

circumflex  anterior,  290 
external,  316 
circumflex  ilii,  312,  315 
internal,  316 
posterior,  289 
coccygeal,  308 
coeliac,  298 
colic,  303 

comes  nervi  ischiat.,  309 
comes  phrenici,  287 
communicans  cerebri,  281 

pedis,  322 
coronaria  dextra,  267 
labii,  273 
sinistra,  267 
ventriculi,  298 
corporis  bulbosi,  310 

cavernosi,  310 
cremasteric,  312 
cystic,  300 
dental,  276 
digitales  manus,  297 


564 


Arteries — continued. 

pedis,  324 
dorsales  poUicis,  291 
dorsalis  linguGe,  272 
carpi,  294 
hallucis,  322 
nasi,  270 
pedis,  320 
penis,  310 
scapulse,  285 
emulgent,  305 
epigastric,  312 

superficial,  318 
ethmoidal,  280 
facial,  272 
femoral,  313 
frontal,  280 
gastric,  298 

gastro-duodenalis,  300  . 
epiploica  dextra,  300 
sinistra,  301 ' 
gluteal,  311 

inferior,  309 
hsemorrhoidal  ext.,  309 
middle,  307 
superior,  305 
inferior,  309, 
hepatic,  299 
ileo-colic,  303 
iliac,  common,  306 
external,  312 
internal,  306 
ilio-lumbar,  310 
infra-orbital,  277 
innominata,  267 
intercostal,  297 

anterior,  287 
superior,  287 
inter-osseous,  296 
intestini  tenuis,  304 
ischiatic,  308 
labial,  273 
lachrymal,  279 
laryngeal,  270 
lateralis  nasi,  273 
lingual,  271 
lumbar,  305 
malleolar,  319 
mammary  internal,  287 
masseteric,  273 
mastoid,  273 
maxillary  internal,  275 
mediastinal,  287, 
meningea,  anterior,  279 
inferior,  274 
media,  276 
parva,  277 
posterior,  284 
mesenteric,  301 

inferior,  304 
metacarpal,  296 
metatarsal,  320 
musculo-plircnic,  287 
nasal,  280 
obturator,  310 


Arteries — continued. 
occipital,  273 
oesophageal,  297 
ophthalmic,  279 
orbitar,  275 
palatine  inferior,  273 

posterior,  277 
palpebral,  280 
pancreatica  magna,  301 
pancreaticas  parvos,  300 
pancreatico-duoden.,  300 
parotidean,  274 
perforantes,  femoral,  316 
palmares,  295 
plantares,  323 
pericardiac,  297 
perineal  superficial,  309 
peroneal,  322 
pharyngea  ascendens,  274 
phrenic,  298 
plantar  external,  324 
internal,  323 
popliteal,  317 
princeps  cervicis,  274 
pollicis,  294 
profunda  cervicis,  287 
femoris,  315 
inferior,  292, 
superior,  292 
pterygoid,  273 
pterygo-palatine,  277 
pudic  external,  315 

internal,  309 
pulmonary,  325,  475 
pyloric,  300 
radial,  292 
radialis  indicis,  295 
ranine,  271 

recurrens  inteross.,  223 
radialis,  293 
tibialis,  319 
ulnaris,  296 
renal,  305 
sacra  media,  305 

lateralis,  311 
scapular  posterior,  285 
sigmoid,  305, 
spermatic,  303 
spheno-palatine,  277 
spinal,  284 
splenic,  300 
stylo-mastoid,  274 
subclavian,  281 
sublingual,  272 
submaxillary,  273 
submental,  273 
subscapular,  285 
supcrficialis  cervicis,  287 

volsB,  293 
supra-orbital,  280 

renal,  305, 

scapular,  285 
sural,  318 
tarsoa,  320 
temporal,  274 


565 


Arteries — continued. 

temporales  profundsE,  275 
thoracic,  289 
thyroidea  inferior,  285 
superior,  270 
tibialis  antica,  318 
postica,  322 
transversalis  colli,  285 
faciei,  274 
humeri,  285 
perinei,  309 
tympanic,  276,  279 
ulnar,  295 
umbilical,  307 
uterine,  310 
vaginal,  310 
vasa  brevia,  301 

intestini  tenuis,  303, 
vertebral,  283 
vesical,  307 
Vidian,  278 
Arthrodia,  101 
Articulations,  104 
Arytenoid  cartilages,  480 
Arytenoid  glands,  485 
Auricles  of  the  heart,  471 
Auriculo-ventricular  openings,  472 

Barry,  Dr.,  researches  of,  548 
Base  of  the  brain,  376 
Bauhini,  valvula,  505 
Bell,  Sir  C,  researches  of,  360 
Berzelius,  analysis  of  bone,  17 
Biliary  ducts,  523 
Bladder,  529 

Bones,  chemical  composition,  17 
developement,  21 
general  anatomy,  17 
structure,  18 

astragalus,  94 

atlas,  24, 

axis,  25 

calcis,  94 

carpus,  79 

clavieula,  73 

coccyx,  30 

costce,  71 

cuboides,  96 

cuneiforme  carpi,  80 

externum  tarsi,  96 
internum,  95 
medium,  96 

ethmoides,  44 

femur,  89 

fibula,  93 

frontale,  34 

humerus,  75 

hyoides,  70 

ilium,  84 

innominatum,  84 

ischium,  86 

lachrymale,  48 

magnum,  81 

malare,  48 

majcillare  superius,  45 


Bones — continued. 

maxillare  inferius,  51 

metacarpus,  82 

metatarsus,  97 

nasi,  45 

naviculare,  95 

occipitale,  30 

palati,  49 

parietale  33 

patella,  91 

phalanges  manus,  84 
pedis,  98 

pisiforme,  80 

pubis,  86 

radius,  77 

sacrum,  29 

scaphoid  es  carpi,  79 
tarsi,  95 

scapula,  73 

semilunare,  80 

sesamoidea  manus,  99 
pedis,  99 

sphenoides,  40 

sternunx,  70 

tarsus,  94 

temporal,  36 

tibia,  91 

trapezoides,  81 

trapezium,  81 

triquetra,  54 

turbinatum  inferius,  51 
superius,  44 

ulna,  76 

unciforme,  82 

unguis,  48 

vertebra  prominens,  26 

vertebrae  cervical,  24 
dorsal,  26 
lumbar,  27 

vomer,  51 

Wormiana,  54 
Botal,  foramen  of,  559 

notice  of,  559 
Bowman,  Mr.,  researches  of,  1 41 
Brain,  362 
Bronchi,  485 
Bronchial  cells,  487 

tubes,  488 
Bronchocele,  486 
Brunn,  Von,  notice  of,  508 
Brunner's  glands,  508 
Bulb,  corpus  spongiosum,  535 
Bulbous  part  of  the  urethra,  538 
Bulbus  olfactorius,  387 
Bursae  mucosae,  103 

Caecum,  502 

Calamus  scriptorius,  374 
Calyces,  528 
Camper's  ligament,  254 
Canal  of  Fontana,  442 

Petit,  445 

Sylvius,  372 
Canals  of  Havers,  14 
Canthi,  446 


566 


INDEX. 


Capillaries,  264 
Capitula  laryngis,  481 
Capsule  of  Glisson,  517 
Capsules  supra-renal,  525 
Caput  gallinaginis,  536 
Cardia,  500 
Carpus,  79 
Cartilag-e,  72 
Cartilages. 

inter-articular  of  the  clavicle, 
119 

inter-articular  of  the  jaw.  111 

inter-articular  of  the  wrist,123 

semilunar,  131 
Cartilaginification,  21 
Caruncula  lachrymalis,  448 
Carunculae  myrtiformes,  550 
Casserian  ganglion,  398 
Cauda  equina,  384 
Cementum,  65 
Centrum  ovale  majus,  367 
minus,  367 
Cerebellum,  375 
Cerebro-spinal  axis,  359 
Cerebrum,  366 
Ceruminous  follicles,  451 
Cervical  ganglia,  430 
Chambers  of  the  eye,  444 
Cheeks,  496 
Chorda3  tendineaj,  473,  475 

vocales,  481 

Willisii,  363 
Choroid  membrane,  440 

plexus,  369,  372,  374 
Cilia,  448 
Ciliary  canal,  442 

ligament,  441 
processes,  442 
Circle  of  Willis,  285 
Circulation,  adult,  473 
foetal,  553 
Clitoris,  549 
Cochlea,  458 

Cock,  Mr.,  researches  of,  396 
CcEliac  axis,  298 
Colon,  503 
Columna  nasi,  435 
ColumnsB  carnse,  474,  476 

papillares,  474 
Commissures,  373,  381 
great,  367 
Conarium,  373 
Concha,  450 

Congestion  of  the  liver,  521 
Coni  rcnales,  527 

vasculosi,  542 
Conjunctiva,  448 

Cooper,  Sir  Astlcy,  researches  of,  556 
Coriuin,  464 
Cornea,  'J39 
Cornicula  laryngis,  481 
Cornu  Ammonis,  370 
Cornua  of  the  ventricles,  367 
Corona  glandis,  534 
Coronary  valve,  472 


Corpora  albicantia,  378 
Arantii,  475 
cavernosa,  535 
Malpighiana,  527 
olivaria,  381 
pisiformia,  378 
pyramidalia,  378 
quadrigemina,  373 
restiformia,  376 
striata,  369 
Corpus  callosum,  367 

cavernosum,  535 
fimbriatum,  370 
geniculatum,  externum,  373 
internum,  373 
Highmorianum,  541 
luteum,  548 
rhomboideum,  376 
spongiosum,  535 
striatum,  369 
Costal  cartilages,  72 
Cotunnius,  notice  of,  458 
Covvper's  glands,  538 
Cranial  nerves,  389 
Cribriform  fascia,  257 
Cricoid  cartilage,  480 
Crico-thyroid  membrane,  481 
Crura  cerebelli,  376 
cerebri,  378 
penis,  535 
Crural  canal,  300 

ring,  258 
Crystalline  lens,  445 
Cuneiform  cartilages,  481 
Cupola,  459 

Curling,  Mr.,  researches  of,  561 
Cuticle,  466 
Cutis,  464 
Cystic  duct,  523 

Dartos,  539 

Davy,  Dr.,  researches  of,  283 
Derbyshire  neck,  486 
Dermis,  464 
Detrusor  urinffi,  532 
Dcutsch,  researches  of,  19 
Diaphragm,  193 
Diaphysis,  21 
Diarthrosis,  101 
Digital  cavity,  370 
Diverging  fibres,  380 
Dorsi-spinal  veins,  343 
Ductus  ad  nasum,  450 

arteriosus,  559 

comm.  choledochus,  523 

cysticus,  523 

cjaculatorius,  537 

hepaticus,  523 

lymphaticus  dexter,  356 

pancreaticus,  524 

prostaticus,  5.32 

thoracicus,  354 

vcnosus,  552 
Duodenum,  50 1 
Dura  mater,  363,  383 


INDEX. 


567 


Ear,  450 

Ejaculatory  duct,  536 
Elastic  tissue,  105 
Enamel,  65 
Enarthrosis,  101 
Encephalon,  3G0 
Endolymph,  461 
Ensiform  cartilage,  71 
Epidermis,  466 
Epididymis,  540 
Epigastric  region,  490 
Epiglottic  gland,  486 
Epiglottis,  481 

Epiglotto-hyoidean  ligament,  481 
Epiphysis,  21 
Epithelium,  505 
Erectile  tissue,  535 
Eustachian  tube,  455 
valve,  472 
Eustachius,  notice  of,  472 
Eye,  438 

brows,  446 

globe,  438 

lashes,  447 

lids,  446 

Falciform  process,  257 
Fallopian  tubes,  547 
Fallopius,  notice  of,  547 
Falx  cerebelli,  364 

cerebri,  364 
Fascia. 

general  anatomy  of,  246 

cervical,  deep,  247 

superficial,  247 

cribriform,  257 

dentata,  384 

iliaca,  251 

inter-columnar,  189 

lata,  257 

lumbar,  191 

obturator,  253 

palmar,  255 

pelvica,  252 

perineal,  253 

plantar,  259 

propria,  258 

recto-vesical,  253 

spermatica,  189 

temporal,  247 

thoracic,  248 

transversalis,  249 
Fauces,  497 
Femoral  arch,  249 

canal,  315 

hernia,  258 

ring,  257 
Fenestra  ovalis,  454 

rotunda,  454 
Fibres  of  the  heart,  479 
Fibro-cartilage,  72 

inter-articular  of  the  clavicle,  119 
jaw.  111 
knee,  131 
wrist,  123 


Fimbrioe,  Fallopian,  558 
Fissure  of  Bichat,  367 
Sylvius,  377 
Fissures  of  the  liver,  513 
Flocculus,  376 
FcEtal  circulation,  255 
Foetus,  anatomy  of,  552 
P'ollicles  of  Liebcrkuhn,  508 
Fontana,  notice  of,  441 
Foramen  caecum,  463 

commune  anterius,  373 
posterius,  373 

Munro,  of,  369 

ovale,  552 

saphenum,  256 

Soemmering,  of,  443 

Winslow,  of,  493 
Foramina  Thebesii,  472 
Fornix,  371 
Fossa  innominata,  450 

navicularis  urethra?,  539 
pudendi,  549 

ovalis,  472 

scaphoides,  450 
Fourchette,  549 
Frasna  epiglottidis,  462 
Fraenum  labii,  549 

lingutE,  462 

preputii,  534 

Galea  capitis,  145 
Galen,  260 
Gall-bladder,  522 
Ganglia,  cervical,  430 

increase  of,  378,  381 

lumbar,  434 

sacral,  434 

semilunar,  433 

structure,  of,  361 

thoracic,  432 
Ganglion  of  Andersch,  393 

Arnold's,  429 

azygos,  434 

cardiac,  432 

carotid,  429 

Casserian,  398 

ciliary,  426 

Cloquet's,  427 

impar,  434 

jugular,  393 

lenticular,  426 

Meckel's,  427 

naso-palatine,  427 

otic,  429 

petrous,  393 

plcxiform,  395 

Ribes,  of,  425 

spheno-palatine,  427 

submaxillary,  428 

thyroid,  431 

vertebral,  431 
Gimbernat's  ligament,  189 
Ginglymus,  101 
Gland,  epiglottic,  485 

lachrymal,  449 


568 


INDEX. 


Gland,  epiglottic, — continued. 

parotid,  497 

pineal,  373 

pituitary,  377 

prostate,  532 

tliyinup,  556 

tliyroid,  48G 
Glands,  ag-grcgate,  508 

ar^'tenoid,  485 

Brunner's,  508 

Cowper's,  538 

duodena],  508 

gastric,  508 

inguinal,  350 

Lieberkuhn's,  508 

lymphatic,  347 

mammary,  550 

mesenteric,  354 

Meibomian,  447 

oesophageal,  508 

Pacchionian,  363 

Peyer's,  508 

pharyngeal,  507 

salivary,  498 

solitary,  508 

sublingual,  498 

submaxillary,  498 

tracheal,  486 
GlanduloB  oderifertE,  534 

Pacchioni,  383 

Tysoni,  534 
Glans  clitoridis,  549 

penis,  534 
Glisson,  notice  of,  493 
Glisson's  capsule,  517 
Globus  major  epididymis,  540 

minor  epididymis,  540 
Glomeruli,  529 
Glottis,  484 

Goodsir,  Mr,,  researches  of,  65 
Goitre,  486 
Gomphosis,  100 
Graafian  vesicles,  548 
Grainger,  Mr.,  researches  of,  360 
Gubernaculum  testis,  561 
Gums,  496 

Guthrie,  Mr.,  researches  of,  532 
Guthrie's  muscle,  197 

Hair,  467 

Hall,  Dr.  Marshall,  researches,  360 

Harmonia,  100 

Haversian  canals,  20 

Heart,  469 

Helicinc  arteries,  536 

Helico-trcma,  459 

Helix,  450 

Hepatic  duct,  518 

Hernia,  congenital,  251 

diaphragmatic,  188 

direct,  251 

encysted,  251 

femoral,  259 

inguinal,  250 
Highmore,  notice  olj  541 


Hilton's  muscle,  484 
Hilus  lienis,  524 

renalis,  527 
Hippocampus  major,  370 

minor,  370 
Horner's  muscle,  147 
Houston,  Mr.,  researches  of,  505 
Humours  of  the  eye,  444 
Hyaloid  membrane,  444 
Hymen,  549 

Hypochondriac  regions,  490 
Hypogastric  region,  490 

Ileo-CBBcal  valve,  505 
Ileum,  502 
Iliac  regions,  490 
Incus,  452 
Infundibula,  528 
Infundibulum,  377 
Inguinal  region,  493 
Inter-articular  cartilages,  of  the  clavicle, 

119 
javir.  111 
wrist,  123 
Inter-columnar  fibres,  187 
Inter-vertebral  substance,  101 
Intestinal  canal,  501 
Iris,  441 

Isthmus  of  the  fauces,  497 
Iter  ad  infundibulum,  373 

a  tertio  ad  quartum  ventriculuni,  373 

Jacob's  membrane,  442 
Jejunum,  502 
Joint,  ankle,  135 

elbow,  121 

hip,  128 

lower  jaw,  110 

knee,  129 

shoulder;  120 

wrist,  125 
Jones,  Mr.,  researches  of,  461 

Kidneys,  526 

Kicrnan,  Mr.,  researches  of,  516 
King,  Mr.  T.  W.,  researches  of,  474 
Krause,  researches  of,  197 

Labia  majora,  549 

minora,  549 
Labyrinth,  460 
Lachrymal  canals,  449 

gland,  449 

papillffi,  447 

puncta,  447 

sac,  449 

tubercles,  447 
Lacteals,  354 
LacunfD,  539 
Lacus  lachrymalis,  446 
Lamina  cribrosa,  439 

spiralis,  459 
Laryngotomy,  481 
Larynx,  480 
Lateral  ventricles,  367 


ii-- 


i 


569 


Lauth,  researches  of,  541 
Lens,  445 

Lenticular  ganglion,  426 
Lieberkuhn's  follicles,  508 
Lien  succenturiatus,  525 
Ligament,  103 
Ligaments,  100 

acromio-clavicular,  119 
alar,  133 

ankle,  of  the,  135 
annular,  of  tiic  ankle,  259 

radius,  123 

wrist,  anterior,  125 

posterior,  255 

arcuatum  externum,  193 

internum,  193 
atlo-axoid,  109 
breve  plantse,  138 
calcaneo-astragaloid,  137 

cuboid,  137 

scaphoid,  137 
capsular  of  the  hip,  128 

jaw,  110 

rib,  112 

shoulder,  120 

thumb,  125 
carpal,  126 

carpo-metacarpal,  126 
common  anterior,  104 

posterior,  104 
conoid,  119 
coracoid,  120 
coraco-acromial,  120 

clavicular,  119 

humeral,  120 
coronary,  123 

of  the  knee,  131 
costo-clavicular,  118 

sternal,  113 

transverse,  112 

vertebral,  112 

xyphoid,  114 
cotyloid,  128 
crico-thyroidean,  481 
crucial,  131 
cruciform,  108 
deltoid,  135 
elbow,  of  the,  121 
epiglotto-hyoidean,  481 
glenoid,  120 
hip-joint,  of  the,  128 
ilio-femoral,  128 
inter-articular  of  ribs,  112 
inter-clavicular,  118 
inter-osseous, 

calcaneo-astragal.  137 

peroneo-tibial,  134 
radio  ulnar,  123 
inter-spinons,  106 
inter-transverse,  106 
inter-vertebral,  105 
knee,  of  the,  129 
lateral  of  the  ankle,  135 

elbow,  121 

jaw,  110 

knee,  130 

phalanges,  foot,  139 

phalanges,  hand,  127 


s — continuf^i^ 
3ral  of  the  \mst. 


72 


Ligaments- 

lateral  of  the  Mst,  125 
liver,  of  the,  512 
longum  plantae,  138 
lumbo-iliac,:114 
lumbo-sacral,  114 
metacarpo-phalangeal,  127 
metatarso-phalangeal,  139 
mucosum,  133 
nuchcB,  173 
oblique,  123 
obturator,  117 
occipito-atloid,  107 

axoid,  108 
odontoid,  108 
orbicular,  123 
palpebral,  447 
patellcB,  130 
peroneo-tibial,  134 
phalanges  of  the  foot,  133 

of  the  hand,  127 
plantar,  long,  138 
plantar,  short,  138 
posticum  Winslowii,  13!) 
ptery  go-maxillary,  110 
pubic,  117 
radio-ulnar,  123 
rhomboid,  118 
rotund  um,  hepatis,  512 
sacro-coccygean,  116 
sacro-iliac,  115 
sacro-ischiatic  anterior,  1 1 6 
posterior,  116 
stellate,  112 
sterno-clavicular,  118 
stylo-maxillary.  111 
sub-flava,  105 
sub-pubic,  117 
supra-spinous,  106 
suspensorium  hepatis,  512 

penis,  534 
tarsal,  136 

tarso-metatarsal,  137 
teres,  128 

thyro-arytenoid,  481 
thyro-hyoidean,  481 
tibio-fibular,  134 
transverse 

of  the  acetabulum,  129 

of  the  ankle,  135 

of  the  atlas,  109 

of  the  knee,  131 

of  the  metacarpus,  126 

of  the  metatarsus,  139 

of  the  scapula,  120 

of  the    semilunar  cartilages, 
131 
trapezoid,  119 
tympanum,  of  the,  45  i 
wrist,  of  the,  125 
Zinn,  of,  14S 
Ligamentura  nuchce,  173 
Limbus  luteus,  443 
Linea  alba,  188 
Lineae  semi-lunares,  1  "JS 

transversse,  307,  374 
Linguctta  laminosa,  376 
Lips,  496 


570 


Liquor  Cotuiinii,  459 
Morgagni,  445 
Scarpa,  of,  4C1 
Liver,  511 

Lobules  of  the  liver,  516 
Lobuli  testis,  541 
Lobulus  auris,  450 

pneumogastricus,  376 
Lobus  caudalus,  514 
quadratus,  514 
Spigelii,  514 
Locus  niger,  378 

perforatus,  378 
Lower,  notice  of,  472 
Lumbar  fascia,  191 

regions,  490 
Lungs,  486 
Lunula,  467 
Lymphatic  glands  and  vessels,  347 

axillary,  349 

bronchial,  352 

cardiac,  353 

cervical,  348 

head  and  neck,  348 

heart,  353 

iliac,  351 

inguinal,  350 

intestines,  354 

kidney,  354 

lacteals,  354 

liver,  353 

lovs^er  extremity,  350 

lungs,  351 

mediastinal,  351 

mesenteric,  354 

pelvic  viscera,  354 

popliteal,  350 

spleen,  353 

stomach,  353 

testicle,  354 

trunk,  351 

upper  extremity,  349 

viscera,  352 
Lyra,  371 


Malleus,  452 

Mammae,  550 

Manmiary  gland,  550 

Mastoid  cells,  455 

Matrix,  467 

Maxillo-pharyngeal  space,  160 

Mayo,  Mr.,  researches  of,  398 

Meatus  auditorius,  451 

urinarius,  female,  550 
male,  496 

Meatuses  of  the  nares,  437 

Meckel's  ganglion,  427 

Meconium,  559 

Mediastinum,  489 

testis,  541 

Medulla  of  bones,  21 

oblongata,  378 

Meibomian  glands,  447 

Meibomius,  notice  of,  447 

Membrana  dentata,  384 
nictitans,  448 
pigmenti,  441 


Membrana  papillaris,  555 

saccilbrmis,  123 
tympani,  452 
Membrane,  choroid,  440 
hyaloid,  444 
Jacob's,  443 
of  the  ventricles,  375 
Membranous  urethra,  53b 
Meniscus,  99 
Mesenteric  glands,  354 
Mesentery,  494 
Meso-colon,  494 
Mcso-rectam,  494 
Metacarpus,  82 
Metatarsus,  97 
Miescher,  researches  of,  19 
Mitral  valves,  476 
Modiolus,  458 
Mons  Veneris,  548 
Morgagni,  notice  of,  445 
Morsus  Diaboli,  547 
Motor  tract,  385 
Mouth,  496 

Mucous  membrane,  structure,  508 
Miiller,  researches  of,  19 
Muscles 

general  anatomy  of,  140 
developement,  143 
structure,  141 
abductor  min.  digiti,  22D 
abduc.  min.  dig.  pedis,  213 
indicis,  221 
pollicis,  218 
pedis,  242 
accelerator  urinse,  197 
accessorius,  243 
abductor  brevis,  231 
longus,  231 
magnus,  232 
min.  digiti,  220 
pollicis,  219 
pedis,  244 
anconeus,  216 
anti-tragicus,  451 
arytenoideus,  482 
aryteno-epiglot.  inf ,  483 
superior,  483 
attollens  aurem,  156 
oculum,  148 
attrahens  aurem,  156 
auricularus,  216 
azygos  uvulae,  169 
basio-glossus,  160 
biceps  flexor  cruris,  233 
cubiti,  207 
biventer  cervicis,  179 
brachialis  anticus,  208 
buccinator,  155 
ccrato-glossus,  160 
cervicalis  ascendens,  178 
circumflcxus  palati,  169 
coccygeus,  200 
complcxus,  179 
compressor  nasi,  151 

urethra;,  198 
constrictor  inferior,  166 
isth.  faucium,  165 
mediuB,  166 


571 


Muscles — continued. 

constrictor  superior,  166 

vaginsB,  200 
coraco-brachialis,  207 
corrugator  supercilii,  147 
cremaster,  190 
crico-arytoenoid  lat.,  482 
posticus,  482 
thyroideus,  482 
crureus,  229 
cucullaris,  173 
deltoid,  206 

depressor  ang.  oris,  153 
labii  inferioris,  153 
labii  sup.  alseque  nasi,  152 
depressor  oculi,  148 
detrusor  urina?,  542 
diapiiragm,  193 
digastricus,  162 
erector  clitoridis,  201 
penis,  197 
spinae,  177 
extensor 

carpi  rad.  brev.,  214 
carpi  rad.  long.,  214 
carpi  ulnaris,  216 
digiti  minimi,  216 
digitor.  brevis,  241 
digitor.  com,,  214 
digitor.  longus,  235 
indicis,  217, 
ossis  metacarpi,  217 
pollicis  proprius,  235 
primi  internodii,  217 
sec.  internodii,  217 
flexor  accessorius,  243 
brevis  digiti  minimi,  220 
digiti  minimi  pedis, 
244 
carpi  radialis,  210 
ulnaris,  212 
digitorum  brevis,  243 

profundus,  212 
sublimis,  211 
.  longus  digit,  pedis,  238 
longus  pollicis  manus,  213 

pedis,  238 
ossis  metacarpi,  218,  220 
pollicis  brevis,  219 
pedis,  244, 
longus,  238 
gastrocnemius,  236 
gemellus  inferior,  226 
superior,  225 
genio-hyo-glossus,  163 

hyoideus,  163 
gluteus  maximus,  224 
medius,  224 
minimus,  224 
gracilis,  232 
helicis  major,  451 
minor,  451 
hyo-glossus,  164 
iliacus,  230 
indicator,  217 
infra-spinatus,  205 
uiter-costales  externi,  186 
interni,  186 


Muscles — continued. 

inter-ossei  manus,  221 

pedis,  241,  245 
inter-spinales,  181 
inter-transversalcs,  181 
intra- costales,  186 
larynx,  of  the,  482 
latissimus  dorsi,  174 
laxator  tympani,  454 
levator  anguli  oris,  152 

scapulae,  174 
ani,  199 

gland ula3  thyroid.,  486 
labii  inferioris,  153 
superioris,  152 
sup.  alcEq.  nasi,  151 
menti,  153 
palati,  168 
palpebrae,  148 
levatores  costarum,  181 
lingualis,  164 
longissimus  dorsi,  177 
longus  colli,  171 
lumbricales  maniis,  220 

pedis,  243 
mallei  externus,  454 
internus,  454 
masseter,  154 
multifidus  spinas,  181 
mylo-hyoideus,  162 
myrtiformis,  152 
obliquus  abdom.  ext.,  188 
abdom.  int.,  189 
capitis  inferior,  180 
superior,  180 
oculi  inferior,  150 
obliquus  superior,  149 
obturator  externus,  226 
obturator  internus,  225 
occipito-frontalis,  145 
omo-hyoidcus,  161 
opponens  digit,  min.,  220 

pollicis,  218 
orbicularis  oris,  151 

palpebrarum,  146 
palato-glossus,  165,  169 
pharyngeus,  169 
palmaris  brevis,  220 
longus,  210 
pectineus,  231 
pectoralis  major,  203 
minor,  203 
peroneus  brevis,  240 
longus,  240 
tertius,  235 
plantaris,  236 
platysma  myoides,  158 
popliteus,  238 
pronator  quadratus,  213 
radii  teres,  210 
psoas  magnus,  230 

parvus,  193 
pterygoideus  ext.,  155 
int.,  155 
pyramidalis  abdom.,  192 

nasi,  150 
pyriformis,  225 
quadratus  femoris,  226 


572 


INDEX. 


Muscles — continued. 

quadratus  lumborum,  193 

menti,  153 
rectus  abdominis,  192 

capitis  ant.  maj.,  170 
min.,  170 
lateralis,  180 
post,  maj.,  180 
min.,  180 
femoris,  228 
oculi  externus,  149 
inferior,  148 
internus,  149 
superior,  148 
retrahens  aurem,  157 
rhomboideus  major,  176 
minor,  174 
risorius  Santorini,  158 
sacro-lumbalis,  177 
sartorius,  228 
scalenus  anticus,  170 

posticus,  171 
semi-spinalis  colli,  180 
dorsi,  180 
semi-membranosus,  233 
semi-tendinosus,  233 
serratus  magnus,  204 

posticus  inf.,  176 
sup.,  176 
soleus,  236 
sphincter  ani,  199 

internus,  199  • 
spinalis  dorsi,  177 
splenius  capitis,  176 

colli,  177 
stapedius,  454 
sterno-hyoideus,  160 

mastoideus,  158 
thyroideus,  160 
stylo-glossus,  165 
hyoideus,  162 
pharyngcus,  167 
subclavius,  2U4 
subcrureus,  229 
subscapularis,  204 
supinator  brevis,  216 
longus,  214 
Eupra-spinalcs,  181 
supra-spinatus,  205 
temporal,  154 
tensor  palati,  1 68 
tarsi,  147 
tympani,  454 
vagina?  fem.,  227 
teres  major,  206 
minor,  205 
thyro-arytcnoidcus,  482 
cpiglottidcus,  483 
hyoideus,  160 
tibialis  anticus,  234 
posticus,  239 
trachelo-inastoideus,  179 
tragicus,  451' 
transversalis  abdom.,  191 

colli,  179 
transversus  auriw,  451 
pedis,  244 
perinei,  197,  200 


Muscles — continued. 

trapezius,  173 
triangularis  oris,  153 

sterni,  188 
triceps  extens.  cruris,  236 
cubiti,  208 
ureters,  of  the,  532 
vastus  exteriuis,  229 
internus,  229 
zygomaticus  major,  152 
minor,  152 
Muscular  fibre,  141 
Musculi  pectinati,  473 
Myolemma,  141 
Myopia,  446 

Naboth,  ovula  of,  546 

Nagel,  Mr.,  researches  of,  526 

Nails,  467 

Nares,  499 

Nasal  duct,  449 

fossffi,  62,  437 
Nasmyth,  Mr.,  researches  of,  69 
Nates  cerebri,  373 
Nerves. 

general  anatomy,  357 
abducentes,  389 
accessorius,  398 
acromiales,  405 
auditory,  387,  461 
auricularis  anterior,  403 
magnus,  405 
posterior,  392 
buccal,  402 
cardiac,  397 
cardiacus  inferior,  431 
magnus,  431 
medius,  431 
minor,  431 
superior,  430 
cervical,  404 
cervico-facial,  392 
chorda  tympani,  391,  428 
ciliary,  399 
circumflex,  413 
claviculares,  405 
cochlear,  461 
communicans  noni,  406 

peronei,  421 
poplitei,  422 
cranial,  389 
crural,  417 

cutaneous  ext.  branch.,  409 
ext.  femoralis,  416 
int.  brachialis,  409 
minor,  410 
post,  femoralis,  421 
spiralis,  412 
dental  anterior,  401 
inferior,  402 
posterior,  401 
descendens  noni,  390 
digastric,  392 
dorsal,  41 3 
eighth  ])!iir,  393 
facial,  391 
femoral,  417 
fifth  pair,  398 


INDEX, 


573 


Nerves — continued. 
first  pair,  38G 
fourth  pair,  390 
frontal,  399 
gastric,  397 
•    genilo-crural,  417 
glossopliaryngeal,  393 
gluteal,  420 

inferior,  421 
gustatory,  402 
hypo-glossal,  389 
ilio-scrotal,  415 
inferior  maxillary,  399 
infra-troehlear,  399 
inguino-cutaneous,  416 
intercostal,  414 
intercosto-humeral,  414 
inter-osseous  anterior,  410 
posterior,  413 
iacliiaticus  major,  422 
minor,  421 
Jacobson's,  394 
lachrymal,  401 
laryngeal  inferior,  397 

super.  396,  430 
lingual,  389 
lumbar,  415 
lumbo-sacral,  419 
masseteric,  401 

maxillaris  inferior,  401 
superior,  399 

median,  410 

molles,  431 

motores  oculorum,  388 

musculo-cutan.,  arm,  409 
leg,  424 

musculo-spiral,  412 

mylo-hyoidean,  402 

nasal,  399 

obturator,  418 

occipitalis  major,  407 
minor,  405 

olfactory,  386 

ophthalmic,  398 

optic,  387 

orbital,  401 

palatine  anterior,  427 
posterior,  427 

palmar,  deep,  411 

superficial,  411,  412 

pathetici,  390 

perforans  Casserii,  409 

perineal,  421 

peroneo-cutaneous,  424 

peroneal,  424 

petrosus  minor,  429 

pharyngeal,  395,  430 

phrenic,  406 

plantar  external,  423 
internal,  423 

pneumogastric,  394 

popliteal,  422 

portio  dura,  391 
mollis,  387 

pterygoid,  402 

pudendalis,  421 

pudic  internal,  421 

pulmonary,  397 


Nerves — continued. 
radial,  412 
recurrent,  397 
respiratory  external,  408 
sacral,  419 

saphenous  external,  422 
long,  418 
short,  418 
second  pair,  387 
sixth  p*r,  389 
spinal,  403 
spinal  accessory,  397 
splanchnicus  major,  433 
minor,  433 
stylo-hyoid,  392 
sub-occipital,  406 
subscapular,  408 
superficialis  colli,  405 

cordis,  430 
superior  maxillary,  399 
supra-orbital,  397 
scapular,  408 
trochlear,  399 
sympatheticus  major,  424 
minor,  393 
temporal,  401 
temporo-facial,  392 
malar,  401 
third  pair,  388 
thoracic  long.,  408 
short,  408 
tibialis  anticus,  424 
posticus,  423 
trifacial,  398 
trigeminus,  398 
trochlearis,  390 
tympanic,  394 
ulnar,  411 
vagus,  394 
vestibular,  461 
Vidian,  427 
Neurilemma,  357 
Nipple,  550 
Nose,  435 
NympliBB,  549 

(Esophagus,  500,  509 
Omentum,  gastro-splenic,  494 

great,  494 

lesser,  492 
Omphalo-mesenteric  vessels,  559 
Optic  commissure,  377 
thalami,  369,  372 
Orbiculare  os,  452 
Orbits,  61 

Ossicula  auditus,  452 
Ossification,  21 
Ostium  abdominale,  547 
Ostium  uterinum,  547 
Otoconitcs,  461 
Ovaries,  547 
Ovula  Graafiana,  549 
Naboth,  of,  546 

Pacchionian  glands,  363 
Palate,  496 
Palmar  arch,  297 
PalpebrtD,  446 


574 


Palpebral  ligaments,  447 

sinuses,  448 
Pancreas,  423 
Panizza,  researches  of,  430 
Papillce  of  the  nail,  467 

of  the  skin,  464 

of  the  tongue,  462 

"caljciformes,  463 

circumvullatDB,  462 

conicae,  463    • 

filiformes,  463 

fungifornies,  463 
Parotid  gland,  497 
Pelvis,  86 

viscera  of,  529 
Penis,  534  , 

Pericardium,  470 
Perichondrium,  21 
Pericranium,  21 
Periosteum,  21 
Peritoneum,  491 
Perspiratory  ducts,  467 
Pes  accessorius,  370 
anserinus,  391 
hippocampi,  370 
Petit,  notice  of,  445 
Peyer,  notice  of,  508 
Peyer's  glands,  508 
Phalanges,  84 
Pharynx,  499 
Pia  mater,  366,  383 
Pigmentum  nigrum,  440 
Pillars  ofthe  palate,  497 
Pineal  gland,  373 
Pinna,  450 
Pituitary  gland,  377 

membrane,  437 
Pleura,  489 
Plexus,  aortic,  434 

axillary,  407 

brachial,  407 

cardiac,  432 

carotid,  429 

cavernous,  429 

cervical  anterior,  404 
posterior,  406 

choroid,  369,  374 

cceliac,  433 

coronary,  432 

gastric,  433 

hepatic,  433 

hypogastric,  434 

lumbar,  415 

mesenteric  inferior,  434 
superior,  434 

oesophageal,  397 

pharyngeal,  395 

phrenic,  433 

prostatic,  338 

pterygoid,  327 

pulmonary,  397,  432 

renal,  433 

sacral,  420 

solar,  433 

spermatic,  434 

splenic,  433 

Hul)maxillary,  404 

supra-renal,  433 


Plexus  uterine,  338 

vertebral,  431 
vesical,  338 
Plica  semilunaris,  448 
PliciE  longitudinales,  503 
Pneumogastric  lobule,  376 
Polypus  of  the  heart,  473 
Pomum  Adami,  480 
Pons  Tarini,  378 
Varolii,  378 
Pores,  468 
Portal  vein,  344,  517 
Portio  dura,  391 

mollis,  388 
Porus  opticus,  439 
Poupart's  ligament,  188 
Prepuce,  534 
Presbyopia,  446 

Processus  e  cerebello  ad  testes,  376 
clavatus,  384 
vermiformes,  376 
Promontory,  454 
Prostate  gland,  532 
Prostatic  urethra,  536 
Protuberantia  annularis,  378 
Pulmonary  artery,  489 

plexuses,  489 
sinuses,  475 
veins,  346 
Puncta  lachrymalia,  447 

vasculosa,  367 
Pupil,  441 

Purliinje,  corpuscules  of,  21 
Pylorus,  500 
Pyramid,  456 
Pyramids,  anterior,  378 
posterior,  374 
of  Wistar,  45 

Raph6,  corporis  callosi,  367 
Receptaculum  chyli,  354 
Rectum,  503 
Regions,  abdominal,  490 
Reil,  island  of,  377 
Respiratory  nerves,  408 

tract,  408 
Rete  mucosum,  465 

testis,  542 
Retina,  442 

Ribcs,  ganglion  of,  425 
Rima  glottidis,  484 
Ring,  external  abdominal,  180 

femoral,  257 

internal  abdominal,  249 
Ruga;,  504 
Ruysch,  notice  of,  441 

Sacculus  laryngis,  484 
proprius,  460 
Salivary  glands,  500 
Saphenous  opening,  257 

veins,  338 
Scala  tympani,  459 
vestibuli,  459 
Scarf-skin,  466 
Scarpa,  notice  of,  461 
Schindylesis,  100 
Schneider,  notice  of,  437 


575 


Schneiderian  membrane,  437 
Sclerotic  coat,  438 
Scrotum,  53J 

Searle,  Mr.,  researches  of,  477 
Sebaceous  glands,  467 
Semicircular  canals,  457 
Semilunar  fibro-cartilages,  ]31 

valves,  473 
Septum  auricularum,  471 
crurale,  259 
lucidum,  371 
pectiniforme,  535 
scroti,  539 
Serous  membrane,  structure,  496 
Sesamoid  bones,  99 
Sheath  of  the  rectus,  192 
Sigmoid  valves,  475 
Sinuses,  structure,  331 
Sinus  aortic,  476 
basilar,  334 
cavernous,  333 
circular,  333 
fourth,  332 
lateral,  333 

longitudinal  inferior,  332 
superior,  331 
occipital  anterior,  334 
posterior,  333 
petrosal  inferior,  333 
superior,  334 
pocularis,  537 
prostatic,  536 
pulmonary,  475 
rectus  or  straight,  332 
transverse,  334 
Skeleton,  23 
Skin,  464 
Skull,  33 

Socia  parotidis,  498 
Soemmering,  notice  of,  443 
Soft  palate,  499 
Spermatic  canal,  250 

cord,  539 
Spheno-maxiliary  ganglion,  427 
Spigel,  notice  of,  514 
Spinal  cord,  384 
nerves,  403 
veins,  343 
Spleen,  524 

Spongy  part  of  the  urethra,  538 
Stapes,  452 
Stenon,  notice  of,  463 
Stenon's  duct,  498 
Stomach,  500 
StriaB,  muscular,  141 
Sub-arachnoidean  fluid,  365 
space,  365 
tissue,  365 
Sublingual  gland,  498 
Submaxillary  gland,  498 
Substantia  perforata,  377 
Sulcus  hepatis,  515 

longitudinal  chorda3  spinal.  384 
Supercilia,  446 
Superficial  fascia,  246 
Supra-renal  capsules,  525 
Suspensory  ligament,  liver,  513 
penis,  535 


Sutures,  54 

Sylvius,  notice  of,  3G6 

Sympathetic  nerve,  424 

Symphysis,  100 

Synarthrosis,  100 

Synovia,  103 

Synovial  membrane,  103 

Tapetum,  440 

Tarin,  Peter,  notice  of,  369 

Tarsal  cartilages,  447 

Tarsus,  94 

Teeth,  63 

Tendo  Achillis,  236 

oculi,  150 
Tendon,  140 
Tenia  semicircularis,  369 

Tarini,  369 
Tentorium  cerebelli,  383 
Testes  cerebri,  373 
Testicles,  539 

descent,  561 
Thalami  optici,  369,  372 
Thebesius,  notice  of,  472 
Theca  vertebralis,  383 
Thoracic  duct,  354 
Thorax,  469 
Thymus  gland,  556 
Thyro-hyoid  membrane,  481 
Thyroid  axis,  285 
Thyroid  cartilage,  480 

gland,  498,  567 
Tod,  Mr.,  researches  of,  451 
Tongue,  462 
Tonsils,  497 

cerebelli,  376 
Torcular  Herophili,  332 
Trachea,  485 
Tractus  motorius,  385 

respiratorius,  390 
Tragus,  450 

Triangles  of  the  neck,  162 
Tricuspid  valves,  473 
Trigone  vesicale,  532 
Trochlearis,  149 
Tuber  cinereum,  377 
Tubercula  quadrigemiiia,  373 
Tuberculum  Loweri,  472 
Tubuli  lactiferi,  550 

seminiferi,  541 
uriniferi,  528 
Tunica  albuginea  oculi,  439 
testis,  541 

erythroides,  540 

nervea,  509 

Ruyschiana,  441 

vaginalis,  541 

vasculosa  testis,  541 
Tympanum,  452 
Tyrrell,  Mr.,  researches  of,  187 
Tyson's  glands,  534 

Umbilical  region,  490 
Urachus,  530,  560 
Ureter,  528 
Urethra,  female,  543 

male,  536 
Uterus,  544 


576 


Utriculus  communis,  460 

Uvea,  442 

Uvula  cerebelli,  376 

palati,  497 

vesicse,  532 

Vagina,  543 
Valve,  arachnoid,  375 
Banhini,  505 
coronary,  472 
Eustachian,  472 
ileo-CiEca],  505 
mitral,  476 
pyloric,  507 
rectum,  of  the,  507 
semilunar,  474,  475 
tricuspid,  473 
Vieussens,  of,  375 
Valvules  conniventes,  505 
Varolius,  notice  of,  378 
Vasa  efferentia,  542 

lactea,  354 

lymphatica,  353 

pampiniformia,  540 

recta,  542 

vasorum,  263 
Vasculum,  abcrrans,  540 
Vas  deferens,  539 
Vkins, 

structure,  328 

angular,  329 

auricular,  330 

axillary,  337 

azygos  major,  343 
minor,  343 

basilic,  336 

cardiac,  344 

cava  inferior,  341 
superior,  340 

cephalic,  337 

cerebellar,  331 

cerebral,  331 

coronary,  344 

corporis  striata,  369 

diploe,  330 

dorsalis  penis,  341 

dorsi-spinal,  343 

emulgent,  342 

facial,  329 

femoral,  338 

frontal,  329 

Galqni,  331 

gastric,  346 

hepatic,  342 

iliac,  340,  341 

innominata,  339 

intercostal  superior,  343 

jugular,  334 

lumbar,  342 

mastoid,  331 

maxillary  internal,  330 

median,  337 

basilic,  337 
cephalic,  337 

medulli-spinal,  344 

meningo-rachidian,  343 


Veins — continued. 

mesenteric  inferior,  3 14 
superior,  345 

occipital,  330 

ovarian,  342 

parietal,  330 

popliteal,  338 

portal,  344 

profunda  femoris,  338 

prostatic,  341 

pulmonary,  346,  475 

radial,  336 

renal,  342 

salvatella,  336 

saphenous  external,  338 
internal,  339 

spermatic,  342 

spinal,  343 

splenic,  345 

subclavian,  338 

temporal,  330 

temporo-maxillary,  330 

Thebesii,  344 

thyroid,  336 

ulnar,  336 

uterine,  341 

vertebral,  335,  343 

vesical,  341 
Velum  interpositum,  366,  371 
pendulum,  palati,  497 
VentE  comites,  325 

Galeni,  372 

vorticoso3,  441 
Ventricle  of  Arantius,  374 
Ventricles  of  the  brain, 
fifth,  371 
fourth,  374 
lateral,  367 
third,  373 

of  the  heart,  473,  475 

of  the  larynx,  484 
Vermiform  process,  375 
Vertebral  aponeurosis,  181 

column,  25 
Veru  montanum,  536 
Vesicula3  seminales,  533 
Vestibule,  456 
Vestibulum  vaginas,  550 
Vibrissffi,  435 

Vidius  Vidus,  notice  of,  427 
Vieussens,  notice  of,  374 
Villi,  507 

Vitreous  humour,  444 
Vulva,  549 

Wharton,  notice  of,  463 
Wharton's  duct,  4!)8 
WiUis,  notice  of,  363 
Wilson's  muscles,  197 
Winslow,  notice  of,  493 
Wistar,  pyramids  (jf,  45 
Wrisberg,  nerve  of,  410 

Zinn,  notice  of,  4<14 
Zonula  ciliaris,  444 
of  Zinn,  444 
Zygoma,  36 


T  HE    EN  D. 


